A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems are equipped with the option of using the SQL (Structured Query Language) for querying and maintaining the database.
History
The term "relational database" was first defined by E. F. Codd at IBM in 1970. Codd introduced the term in his research paper "A Relational Model of Data for Large Shared Data Banks".
In this paper and later papers, he defined what he meant by
"relational". One well-known definition of what constitutes a relational
database system is composed of Codd's 12 rules. However, no commercial implementations of the relational model conform to all of Codd's rules, so the term has gradually come to describe a broader class of database systems, which at a minimum:
Present the data to the user as relations (a presentation in tabular form, i.e. as a collection of tables with each table consisting of a set of rows and columns);
Provide relational operators to manipulate the data in tabular form.
IBM UK Scientific Centre at Peterlee – IS1 (1970–72) and its successor, PRTV (1973–79)
The most common definition of an RDBMS is a product that presents a
view of data as a collection of rows and columns, even if it is not
based strictly upon relational theory. By this definition, RDBMS products typically implement some but not all of Codd's 12 rules.
A second school of thought argues that if a database does not
implement all of Codd's rules (or the current understanding on the
relational model, as expressed by Christopher J. Date, Hugh Darwen
and others), it is not relational. This view, shared by many theorists
and other strict adherents to Codd's principles, would disqualify most
DBMSs as not relational. For clarification, they often refer to some
RDBMSs as truly-relational database management systems (TRDBMS), naming others pseudo-relational database management systems (PRDBMS).
As of 2009, most commercial relational DBMSs employ SQL as their query language.
Alternative query languages have been proposed and implemented, notably the pre-1996 implementation of Ingres QUEL.
A relational model organizes data into one or more tables (or "relations") of columns and rows, with a unique key identifying each row. Rows are also called records or tuples.
Columns are also called attributes. Generally, each table/relation
represents one "entity type" (such as customer or product). The rows
represent instances of that type of entity (such as "Lee" or "chair")
and the columns representing values attributed to that instance (such as
address or price).
For example, each row of a class table corresponds to a class,
and a class corresponds to multiple students, so the relationship
between the class table and the student table is "one to many"
Keys
Each row in a
table has its own unique key. Rows in a table can be linked to rows in
other tables by adding a column for the unique key of the linked row
(such columns are known as foreign keys). Codd showed that data relationships of arbitrary complexity can be represented by a simple set of concepts.
Part of this processing involves consistently being able to
select or modify one and only one row in a table. Therefore, most
physical implementations have a unique primary key
(PK) for each row in a table. When a new row is written to the table, a
new unique value for the primary key is generated; this is the key that
the system uses primarily for accessing the table. System performance
is optimized for PKs. Other, more natural keys may also be identified and defined as alternate keys
(AK). Often several columns are needed to form an AK (this is one
reason why a single integer column is usually made the PK). Both PKs and
AKs have the ability to uniquely identify a row within a table.
Additional technology may be applied to ensure a unique ID across the
world, a globally unique identifier, when there are broader system requirements.
The primary keys within a database are used to define the
relationships among the tables. When a PK migrates to another table, it
becomes a foreign key in the other table. When each cell can contain
only one value and the PK migrates into a regular entity table, this
design pattern can represent either a one-to-one or one-to-many relationship. Most relational database designs resolve many-to-many
relationships by creating an additional table that contains the PKs
from both of the other entity tables – the relationship becomes an
entity; the resolution table is then named appropriately and the two FKs
are combined to form a PK. The migration of PKs to other tables is the
second major reason why system-assigned integers are used normally as
PKs; there is usually neither efficiency nor clarity in migrating a
bunch of other types of columns.
Relationships
Relationships are a logical connection between different tables, established on the basis of interaction among these tables.
Transactions
In order for a database management system (DBMS) to operate efficiently and accurately, it must use ACID transactions.
Stored procedures
Part of the programming within a RDBMS is accomplished using stored procedures
(SPs). Often procedures can be used to greatly reduce the amount of
information transferred within and outside of a system. For increased
security, the system design may grant access to only the stored
procedures and not directly to the tables. Fundamental stored procedures
contain the logic needed to insert new and update existing data. More
complex procedures may be written to implement additional rules and
logic related to processing or selecting the data.
In a relational database, a relation is a set of tuples that have the same attributes.
A tuple usually represents an object and information about that object.
Objects are typically physical objects or concepts. A relation is
usually described as a table, which is organized into rows and columns. All the data referenced by an attribute are in the same domain and conform to the same constraints.
The relational model specifies that the tuples of a relation have
no specific order and that the tuples, in turn, impose no order on the
attributes. Applications access data by specifying queries, which use
operations such as select to identify tuples, project to identify attributes, and join to combine relations. Relations can be modified using the insert, delete, and update
operators. New tuples can supply explicit values or be derived from a
query. Similarly, queries identify tuples for updating or deleting.
Tuples by definition are unique. If the tuple contains a candidate
or primary key then obviously it is unique; however, a primary key need
not be defined for a row or record to be a tuple. The definition of a
tuple requires that it be unique, but does not require a primary key to
be defined. Because a tuple is unique, its attributes by definition
constitute a superkey.
All data are stored and accessed via relations.
Relations that store data are called "base relations", and in
implementations are called "tables". Other relations do not store data,
but are computed by applying relational operations to other relations.
These relations are sometimes called "derived relations". In
implementations these are called "views"
or "queries". Derived relations are convenient in that they act as a
single relation, even though they may grab information from several
relations. Also, derived relations can be used as an abstraction layer.
A domain describes the set of possible values for a given attribute,
and can be considered a constraint on the value of the attribute.
Mathematically, attaching a domain to an attribute means that any value
for the attribute must be an element of the specified set. The character
string "ABC", for instance, is not in the integer domain, but the integer value 123
is. Another example of domain describes the possible values for the
field "CoinFace" as ("Heads","Tails"). So, the field "CoinFace" will not
accept input values like (0,1) or (H,T).
Constraints
Constraints
are often used to make it possible to further restrict the domain of an
attribute. For instance, a constraint can restrict a given integer
attribute to values between 1 and 10. Constraints provide one method of
implementing business rules
in the database and support subsequent data use within the application
layer. SQL implements constraint functionality in the form of check constraints.
Constraints restrict the data that can be stored in relations. These are usually defined using expressions that result in a boolean
value, indicating whether or not the data satisfies the constraint.
Constraints can apply to single attributes, to a tuple (restricting
combinations of attributes) or to an entire relation.
Since every attribute has an associated domain, there are constraints (domain constraints). The two principal rules for the relational model are known as entity integrity and referential integrity.
Every relation/table has a primary key, this being a consequence of a relation being a set.
A primary key uniquely specifies a tuple within a table. While natural
attributes (attributes used to describe the data being entered) are
sometimes good primary keys, surrogate keys
are often used instead. A surrogate key is an artificial attribute
assigned to an object which uniquely identifies it (for instance, in a
table of information about students at a school they might all be
assigned a student ID in order to differentiate them). The surrogate key
has no intrinsic (inherent) meaning, but rather is useful through its
ability to uniquely identify a tuple.
Another common occurrence, especially in regard to N:M cardinality is
the composite key. A composite key is a key made up of two or more attributes within a table that (together) uniquely identify a record.
Foreign key refers to a field in a relational table that matches the
primary key column of another table. It relates the two keys. Foreign
keys need not have unique values in the referencing relation. A foreign
key can be used to cross-reference
tables, and it effectively uses the values of attributes in the
referenced relation to restrict the domain of one or more attributes in
the referencing relation. The concept is described formally as: "For all
tuples in the referencing relation projected over the referencing
attributes, there must exist a tuple in the referenced relation
projected over those same attributes such that the values in each of the
referencing attributes match the corresponding values in the referenced
attributes."
A stored procedure is executable code that is associated with, and
generally stored in, the database. Stored procedures usually collect and
customize common operations, like inserting a tuple into a relation, gathering statistical information about usage patterns, or encapsulating complex business logic and calculations. Frequently they are used as an application programming interface
(API) for security or simplicity. Implementations of stored procedures
on SQL RDBMS's often allow developers to take advantage of procedural extensions (often vendor-specific) to the standard declarative SQL syntax.
Stored procedures are not part of the relational database model, but all commercial implementations include them.
An index is one way of providing quicker access to data. Indices can be created on any combination of attributes on a relation. Queries that filter using those attributes can find matching tuples directly using the index (similar to Hash table lookup), without having to check each tuple in turn. This is analogous to using the index of a book
to go directly to the page on which the information you are looking for
is found, so that you do not have to read the entire book to find what
you are looking for. Relational databases typically supply multiple
indexing techniques, each of which is optimal for some combination of
data distribution, relation size, and typical access pattern. Indices
are usually implemented via B+ trees, R-trees, and bitmaps.
Indices are usually not considered part of the database, as they are
considered an implementation detail, though indices are usually
maintained by the same group that maintains the other parts of the
database. The use of efficient indexes on both primary and foreign keys
can dramatically improve query performance. This is because B-tree
indexes result in query times proportional to log(n) where n is the
number of rows in a table and hash indexes result in constant time
queries (no size dependency as long as the relevant part of the index
fits into memory).
Queries made against the relational database, and the derived relvars in the database are expressed in a relational calculus or a relational algebra.
In his original relational algebra, Codd introduced eight relational
operators in two groups of four operators each. The first four operators
were based on the traditional mathematical set operations:
The union operator (υ) combines the tuples of two relations and removes all duplicate tuples from the result. The relational union operator is equivalent to the SQL UNION operator.
The intersection
operator (∩) produces the set of tuples that two relations share in
common. Intersection is implemented in SQL in the form of the INTERSECT operator.
The set difference
operator (-) acts on two relations and produces the set of tuples from
the first relation that do not exist in the second relation. Difference
is implemented in SQL in the form of the EXCEPT or MINUS operator.
The cartesian product
(X) of two relations is a join that is not restricted by any criteria,
resulting in every tuple of the first relation being matched with every
tuple of the second relation. The cartesian product is implemented in
SQL as the Cross join operator.
The remaining operators proposed by Codd involve special operations specific to relational databases:
The selection, or restriction, operation (σ) retrieves tuples
from a relation, limiting the results to only those that meet a specific
criterion, i.e. a subset in terms of set theory. The SQL equivalent of selection is the SELECT query statement with a WHERE clause.
The projection operation (π) extracts only the specified attributes from a tuple or set of tuples.
The join operation defined for relational databases is often
referred to as a natural join (⋈). In this type of join, two relations
are connected by their common attributes. MySQL's approximation of a
natural join is the Inner join
operator. In SQL, an INNER JOIN prevents a cartesian product from
occurring when there are two tables in a query. For each table added to a
SQL Query, one additional INNER JOIN is added to prevent a cartesian
product. Thus, for N tables in an SQL query, there must be N−1 INNER
JOINS to prevent a cartesian product.
The relational division
(÷) operation is a slightly more complex operation and essentially
involves using the tuples of one relation (the dividend) to partition a
second relation (the divisor). The relational division operator is
effectively the opposite of the cartesian product operator (hence the
name).
Other operators have been introduced or proposed since Codd's
introduction of the original eight including relational comparison
operators and extensions that offer support for nesting and hierarchical
data, among others.
Normalization was first proposed by Codd as an integral part of the
relational model. It encompasses a set of procedures designed to
eliminate non-simple domains (non-atomic values) and the redundancy
(duplication) of data, which in turn prevents data manipulation
anomalies and loss of data integrity. The most common forms of
normalization applied to databases are called the normal forms.
Connolly and Begg define Database Management System (DBMS) as a
"software system that enables users to define, create, maintain and
control access to the database". RDBMS is an extension of that acronym that is sometimes used when the underlying database is relational.
An alternative definition for a relational database management system is a database management system (DBMS) based on the relational model. Most databases in widespread use today are based on this model.
RDBMSs have been a common option for the storage of information
in databases used for financial records, manufacturing and logistical
information, personnel data, and other applications since the 1980s.
Relational databases have often replaced legacy hierarchical databases and network databases,
because RDBMS were easier to implement and administer. Nonetheless,
relational stored data received continued, unsuccessful challenges by object database management systems in the 1980s and 1990s, (which were introduced in an attempt to address the so-called object–relational impedance mismatch between relational databases and object-oriented application programs), as well as by XML database management systems in the 1990s. However, due to the expanse of technologies, such as horizontal scaling of computer clusters, NoSQL databases have recently become popular as an alternative to RDBMS databases.
A coal power plant in Germany. Fee and dividend will make fossil fuels – coal, oil, and gas – less competitive as a fuel than other options.
A carbon fee and dividend or climate income is a system to reduce greenhouse gas emissions and address climate change. The system imposes a carbon tax on the sale of fossil fuels,
and then distributes the revenue of this tax over the entire population
(equally, on a per-person basis) as a monthly income or regular
payment.
Since the adoption of the system in Canada and Switzerland, it has gained increased interest worldwide as a cross-sector and socially just approach to reducing emissions and tackling climate change.
Designed to maintain or improve economic vitality while speeding the transition to a sustainable energy economy, carbon fee and dividend has been proposed as an alternative to emission reduction mechanisms such as complex regulatory approaches, cap and trade or a straightforward carbon tax. While there is general agreement among scientists and economists
on the need for a carbon tax, economists are generally neutral on
specific uses for the revenue, though there tends to be more support
than opposition for returning the revenue as a dividend to taxpayers.
Structure
The basic structure of carbon fee and dividend is as follows:
A fee is levied on fuels at their point of origin into the
economy, such as the well, mine, or port of entry. The fee is based upon
the carbon content of a given fuel, with a commonly-proposed starting
point being $10–16 /t of carbon that would be emitted once the fuel is burned.
The fee is progressively increased, providing a steady, predictable
price signal and incentivizing early transition to low-carbon energy
sources and products.
A border tax adjustment is levied on imports from nations that lack
their own equivalent fee on carbon. For example, if the United States
legislated a carbon fee-and-dividend system, China would face the choice
of paying carbon fees to the United States or creating its own internal
carbon pricing system. This would leverage American economic power to
incentivize carbon pricing around the world.
Some or all of the fee is returned to households as an energy
dividend. Returning 100% of net fees results in a revenue-neutral carbon
fee-and-dividend system; this revenue neutrality often appeals to
conservatives, such as former Secretary of State George Shultz, who want to reduce emissions without increasing the size and funding of the federal government.
In order to maximize effectiveness, the amount of the fee would be
regulated based on the scientific assessments from both economic and climate science in order to balance the size and speed of fee progression.
Advantages
A climate income has several notable advantages over other emission reduction mechanisms:
Social justice and acceptability. While there is broad scientific consensus that a carbon tax is the most powerful way to reduce emissions, such a tax necessarily increases prices and the cost of living.
By handing out the revenue of this tax as a universal climate income,
the price rise is largely compensated. It has been calculated that in
total, low and middle incomes would go up under a system of climate
income.
Market based and cross-sector. Unlike complex regulatory approaches,
a fossil fuel fee allows market forces to reduce emissions in the most
efficient and cost effective way.
Cross-sector. There is a broad range of sources of carbon emissions. Regulatory approaches and emissions trading
often address only one or a couple of sectors. A truly universal fossil
fuel fee addresses all these sectors at once. Moreover, through a
universal price on CO2-equivalent emissions, the fee can cover other greenhouse gases (such as methane and nitrous oxide) or emission sectors (industry, agriculture) as well.
Compatible. The mechanism is compatible with other measures and
regulations imposed by the government, such as investments in education,
research and infrastructure.
Revenue neutral. A climate income would not increase the budget of the government, or utilise the imposed carbon fee as a means to balance the government deficit.
Carbon fee and dividend should avoid fuel protests that have occurred in many places.
Studies
Energy Modeling Forum study 2012
In late 2012 the Energy Modeling Forum (EMF), coordinated by Stanford University, released its EMF 29 study titled "The role of border carbon adjustment in unilateral climate policy". It is well understood that unilateral climate policy can lead to emissions leakage.
As one example, trade-exposed emissions-intensive industries may
simply relocate to regions with laxer climate protection. A border
carbon adjustment (BCA) program can help counter this and related
effects. Under such a policy, tariffs are levied on the carbon embodied
in imported goods from unregulated trading partners while the original
climate protection payments for exported goods are rebated. The study finds that the BCA programs evaluated:
shift substantial costs from abating OECD counties to non-abating non-OECD countries
In light of these findings, the study recommends care when designing and implementing BCA programs. Moreover, the regressive impact of shifting part of the abatement burden southward conflicts with the UNFCCC
principle of common but differentiated responsibility and respective
capabilities, which explicitly acknowledges that developing countries
have less ability to shoulder climate protection measures.
Regional Economic Models study 2014
A 2014 economic impact analysis by Regional Economic Models, Incorporated (REMI) concluded that a carbon fee that began at US$10 per ton and increased by US$10
per year, with all net revenue returned to households as an energy
dividend, would carry substantial environmental, health, and economic
benefits:[
CO2 emissions in the United States would decrease to 50% of 1990 levels in the first 20 years.
Over the same timespan, reductions in airborne pollution that accompanies CO2 emissions would result in 230,000 fewer premature deaths.
Regular dividend payments would stimulate the U.S. economy, leading to the creation of 2.8 million jobs over baseline during the program's first two decades.
The stimulative effect was also found to positively affect national GDP, adding $70–85 billion/year for a cumulative 20-year increase of $1.375 trillion over baseline (the approximate equivalent of adding an additional year of growth during that span).
International Institute for Applied Systems Analysis study 2016
A 2016 working paper from the International Institute for Applied Systems Analysis (IIASA) looked more narrowly at the impact of a proposed carbon fee and dividend on American households during the first year.
Due to the shorter window analyzed (which did not allow for
considerations of changes to personal energy use under the policy) the
paper found a smaller percentage of households benefiting from carbon
fee and dividend than the REMI report summarized above (53% versus
approximately two-thirds in the REMI report). It also found that an
additional 19% of households suffered a loss of less than 0.2% of annual
income, an amount that might be experienced as effectively "breaking
even" by households in the upper income quintiles most likely affected.
Implementation
Revenue recycling in real-world carbon tax schemes
As of 2021, Switzerland and Canada were the only two countries with
implemented fee and dividend policies. In Switzerland, the carbon tax
refund is returned to citizens as a discount on their health insurance;
an annual notification of the benefit appears on their health insurance
forms. Canada began rolling out a federal fee and dividend scheme from
2019 (though not to the provinces that already had a province level
scheme: British Columbia and Alberta).
The Canadian federal carbon tax rebate is made via a credit given to
one adult in each household (though based on total household size,
including children).
The British Columbia carbon tax could be considered as "fee and dividend", although there are some differences.
Rather than entirely or mostly being returned as a dividend to
households, 73% of the carbon tax is used to reduce corporate and small
business taxes. Unlike most governments, British Columbia's electricity
portfolio largely consists of hydroelectric power and their energy
costs, even with the tax, are lower than most countries.
12 CHF in 2008 24 CHF in 2009 36 CHF in 2010 60 CHF in 2014 84 CHF in 2016
67% for citizens and companies
Political support
United States
Carbon fee and dividend is the preferred climate solution of Citizens' Climate Lobby (CCL).
Citizens' Climate Lobby argues that a fee-and-dividend policy will be
easier to adopt and adjust than relatively complicated cap-and-trade or
regulatory approaches, enabling a smooth, economically-positive
transition to a low-carbon energy economy.
James Hansen, Director of the NASAGoddard Institute for Space Studies has frequently promoted awareness of carbon fee and dividend through his writings and frequent public appearances, as well as his position at Columbia University.
A Carbon Dividends plan has been proposed by the Climate Leadership Council,
which counts among its members 27 Nobel laureates, 15 Fortune 100
companies, all four past chairs of the Federal Reserve, and over 3000 US
economists. Among those supporting the Climate Leadership Council's
Carbon Dividends Plan are Greg Mankiw, Larry Summers, James Baker, Henry Paulson, Ted Halstead, and Ray Dalio. It claims to be the most popular, equitable and pro-growth climate solution.
Inspired by the market-friendly structure of carbon fee and dividend, Republican Congressman Bob Inglis introduced H.R. 2380 (the 'Raise Wages, Cut Carbon Act of 2009') in the U.S. House of Representatives on May 13, 2009. Concerned about energy infrastructure as an issue of national security, he supports Fee and Dividend as a reliable means of reducing dependence on foreign oil.
Another bill partly inspired by the Fee and Dividend structure was introduced by Democratic Congressman John B. Larson on July 16, 2015. H.R. 3104, or the "America's Energy Security Trust Fund Act of 2015" includes a steadily rising price on carbon
but uses some revenue for job retraining, and returns the remainder of
revenue via a payroll tax cut rather than direct dividend payments.
On September 1, 2016, the California Assembly Joint Resolution
43, "Williams. Greenhouse gases: climate change", was filed, having
passed both houses.
The measure urges the United States Congress to enact a tax on
carbon-based fossil fuels. The proposal is revenue-neutral, with all
money collected going to the bottom 2⁄3
of American households. It may have difficulty passing in Congress
because it would be considered a tax, but if households were to receive
an equal share in the form of a dividend then the legislation should
properly class as a carbon fee. Thus California's recommendation for
national legislation is perhaps close to being acceptable to Congress.
A similar bill, the Climate Action Rebate Act, was introduced on July 25, 2019, into the Senate by Democrats Chris Coons and Dianne Feinstein and into the House of Representatives by Democrat Jimmy Panetta. This bill's carbon fee would also start at $15 per ton of CO2-equivalent, but it would increase by $15 each year. The revenue would be split between dividends, infrastructure, research and development, and transition assistance.
In the European Union a petition (addressed to the European Commission) was started on May 6, 2019, with the request to introduce a Climate Income in the EU. The petition is a registered European Citizens' Initiative,
so if it reaches 1 million signatures, the topic will be placed on the
agenda of the European Commission, and will be considered to form a
legislative proposal.
Australia
An Australian version was proposed by Professors Richard Holden and Rosalind Dixon at the University of New South Wales (UNSW) and launched by Member for Wentworth Professor Kerryn Phelps AM MP. Surveys conducted by UNSW showed that the proposal would receive 73% support.
Opposition
There are objections on the way the tax revenue is used. Emeritus professor of management Henry Jacoby, formerly of the Massachusetts Institute of Technology, reviewed some of the more common concerns in a Guardian article in January 2021, particularly the stigma of taxation's perceived unpopularity. Some opponents are concerned with governments possibly not returning the revenue to people.
A 2021 study looking at the only two countries with implemented carbon
dividends – Canada and Switzerland – found that the news of the funds
raised being returned to the public had little impact on the carbon
taxes unpopularity, and that among Canadian conservatives it may even
have increased opposition.
Length measurement, distance measurement, or range measurement (ranging) refers to the many ways in which length, distance, or range can be measured.
The most commonly used approaches are the rulers, followed by
transit-time methods and the interferometer methods based upon the speed of light.
For objects such as crystals and diffraction gratings, diffraction is used with X-rays and electron beams. Measurement techniques for three-dimensional structures very small in every dimension use specialized instruments such as ion microscopy coupled with intensive computer modeling.
Standard rulers
The ruler the simplest kind of length measurement tool: lengths are defined by printed marks or engravings on a stick. The metre was initially defined using a ruler before more accurate methods became available.
Gauge blocks are a common method for precise measurement or calibration of measurement tools.
For small or microscopic objects, microphotography where the
length is calibrated using a graticule can be used. A graticule is a
piece that has lines for precise lengths etched into it. Graticules may
be fitted into the eyepiece or they may be used on the measurement
plane.
Transit-time measurement
The
basic idea behind a transit-time measurement of length is to send a
signal from one end of the length to be measured to the other, and back
again. The time for the round trip is the transit time Δt, and the
length ℓ is then 2ℓ = Δt*"v",with v the speed of propagation of the signal, assuming that is the same in both directions. If light is used for the signal, its speed depends upon the medium in which it propagates; in SI units the speed is a defined value c0 in the reference medium of classical vacuum.
Thus, when light is used in a transit-time approach, length
measurements are not subject to knowledge of the source frequency (apart
from possible frequency dependence of the correction to relate the
medium to classical vacuum), but are subject to the error in measuring
transit times, in particular, errors introduced by the response times of
the pulse emission and detection instrumentation. An additional
uncertainty is the refractive index correction relating the medium used to the reference vacuum, taken in SI units to be the classical vacuum. A refractive index of the medium larger than one slows the light.
Transit-time measurement underlies most radio navigation systems for boats and aircraft, for example, radar and the nearly obsolete Long Range Aid to Navigation LORAN-C.
For example, in one radar system, pulses of electromagnetic radiation
are sent out by the vehicle (interrogating pulses) and trigger a
response from a responder beacon. The time interval between the sending and the receiving of a pulse is monitored and used to determine a distance. In the global positioning system
a code of ones and zeros is emitted at a known time from multiple
satellites, and their times of arrival are noted at a receiver along
with the time they were sent (encoded in the messages). Assuming the
receiver clock can be related to the synchronized clocks on the
satellites, the transit time can be found and used to provide the
distance to each satellite. Receiver clock error is corrected by
combining the data from four satellites.
Such techniques vary in accuracy according to the distances over
which they are intended for use. For example, LORAN-C is accurate to
about 6 km, GPS about 10 m, enhanced GPS, in which a correction signal is transmitted from terrestrial stations (that is, differential GPS (DGPS)) or via satellites (that is, Wide Area Augmentation System (WAAS)) can bring accuracy to a few meters or < 1 meter,
or, in specific applications, tens of centimeters. Time-of-flight
systems for robotics (for example, Laser Detection and Ranging LADAR and Light Detection and Ranging LIDAR) aim at lengths of 10 - 100 m and have an accuracy of about 5 – 10 mm
Interferometer measurements
Measuring a length in wavelengths of light using an interferometer.
In many practical circumstances, and for precision work, measurement
of dimension using transit-time measurements is used only as an initial
indicator of length and is refined using an interferometer.Generally, transit time measurements are preferred for longer lengths, and interferometers for shorter lengths.
The figure shows schematically how length is determined using a Michelson interferometer: the two panels show a laser source emitting a light beam split by a beam splitter (BS) to travel two paths. The light is recombined by bouncing the two components off a pair of corner cubes
(CC) that return the two components to the beam splitter again to be
reassembled. The corner cube serves to displace the incident from the
reflected beam, which avoids some complications caused by superposing
the two beams.
The distance between the left-hand corner cube and the beam splitter is
compared to that separation on the fixed leg as the left-hand spacing
is adjusted to compare the length of the object to be measured.
In the top panel the path is such that the two beams reinforce
each other after reassembly, leading to a strong light pattern (sun).
The bottom panel shows a path that is made a half wavelength longer by
moving the left-hand mirror a quarter wavelength further away,
increasing the path difference by a half wavelength. The result is the
two beams are in opposition to each other at reassembly, and the
recombined light intensity drops to zero (clouds). Thus, as the spacing
between the mirrors is adjusted, the observed light intensity cycles
between reinforcement and cancellation as the number of wavelengths of
path difference changes, and the observed intensity alternately peaks
(bright sun) and dims (dark clouds). This behavior is called interference and the machine is called an interferometer. By counting fringes
it is found how many wavelengths long the measured path is compared to
the fixed leg. In this way, measurements are made in units of
wavelengths λ corresponding to a particular atomic transition. The length in wavelengths can be converted to a length in units of metres if the selected transition has a known frequency f. The length as a certain number of wavelengths λ is related to the metre using λ = c0 / f. With c0
a defined value of 299,792,458 m/s, the error in a measured length in
wavelengths is increased by this conversion to metres by the error in
measuring the frequency of the light source.
By using sources of several wavelengths to generate sum and difference beat frequencies, absolute distance measurements become possible.
This methodology for length determination requires a careful
specification of the wavelength of the light used, and is one reason for
employing a laser
source where the wavelength can be held stable. Regardless of
stability, however, the precise frequency of any source has linewidth
limitations.
Other significant errors are introduced by the interferometer itself;
in particular: errors in light beam alignment, collimation and
fractional fringe determination. Corrections also are made to account for departures of the medium (for example, air) from the reference medium of classical vacuum. Resolution using wavelengths is in the range of ΔL/L ≈ 10−9 – 10−11 depending upon the length measured, the wavelength and the type of interferometer used.
The measurement also requires careful specification of the medium in which the light propagates. A refractive index correction is made to relate the medium used to the reference vacuum, taken in SI units to be the classical vacuum.
These refractive index corrections can be found more accurately by
adding frequencies, for example, frequencies at which propagation is
sensitive to the presence of water vapor. This way non-ideal
contributions to the refractive index can be measured and corrected for
at another frequency using established theoretical models.
It may be noted again, by way of contrast, that the transit-time
measurement of length is independent of any knowledge of the source
frequency, except for a possible dependence of the correction relating
the measurement medium to the reference medium of classical vacuum,
which may indeed depend on the frequency of the source. Where a pulse
train or some other wave-shaping is used, a range of frequencies may be
involved.
Diffraction measurements
For
small objects, different methods are used that also depend upon
determining size in units of wavelengths. For instance, in the case of a
crystal, atomic spacings can be determined using X-ray diffraction. The present best value for the lattice parameter of silicon, denoted a, is:
a = 543.102 0504(89) × 10−12 m,
corresponding to a resolution of ΔL/L ≈ 3 × 10−10. Similar techniques can provide the dimensions of small structures repeated in large periodic arrays like a diffraction grating.
Such measurements allow the calibration of electron microscopes, extending measurement capabilities. For non-relativistic electrons in an electron microscope, the de Broglie wavelength is:
with V the electrical voltage drop traversed by the electron, me the electron mass, e the elementary charge, and h the Planck constant.
This wavelength can be measured in terms of inter-atomic spacing using a
crystal diffraction pattern, and related to the metre through an
optical measurement of the lattice spacing on the same crystal. This
process of extending calibration is called metrological traceability. The use of metrological traceability to connect different regimes of measurement is similar to the idea behind the cosmic distance ladder
for different ranges of astronomical length. Both calibrate different
methods for length measurement using overlapping ranges of
applicability.
Far and moving targets
Ranging is technique that measures distance or slant range from the observer to a target, especially a far and moving target.
Other devices which measure distance using trigonometry are stadiametric, coincidence and stereoscopic rangefinders.
Older methodologies that use a set of known information (usually
distance or target sizes) to make the measurement, have been in regular
use since the 18th century.
Special ranging makes use of actively synchronized transmission and travel time
measurements. The time difference between several received signals is
used to determine exact distances (upon multiplication by the speed of light). This principle is used in satellite navigation.
In conjunction with a standardized model of the Earth's surface, a
location on that surface may be determined with high accuracy. Ranging
methods without accurate time synchronization of the receiver are called
pseudorange, used, for example, in GPS positioning.
With other systems ranging is obtained from passive radiation measurements only: the noise or radiationsignature of the object generates the signal that is used to determine range. This asynchronous method requires multiple measurements to obtain a range by taking multiple bearings instead of appropriate scaling of active pings, otherwise the system is just capable of providing a simple bearing from any single measurement.
Combining several measurements in a time sequence leads to tracking and tracing. A commonly used term for residing terrestrial objects is surveying.
Other techniques
Measuring dimensions of localized structures (as opposed to large arrays of atoms like a crystal), as in modern integrated circuits, is done using the scanning electron microscope.
This instrument bounces electrons off the object to be measured in a
high vacuum enclosure, and the reflected electrons are collected as a
photodetector image that is interpreted by a computer. These are not
transit-time measurements, but are based upon comparison of Fourier transforms
of images with theoretical results from computer modeling. Such
elaborate methods are required because the image depends on the
three-dimensional geometry of the measured feature, for example, the
contour of an edge, and not just upon one- or two-dimensional
properties. The underlying limitations are the beam width and the
wavelength of the electron beam (determining diffraction), determined, as already discussed, by the electron beam energy.
The calibration of these scanning electron microscope measurements is
tricky, as results depend upon the material measured and its geometry. A
typical wavelength is 0.5 Å, and a typical resolution is about 4 nm.
Nuclear Overhauser effect spectroscopy (NOESY) is a specialized type of nuclear magnetic resonance spectroscopy
where distances between atoms can be measured. It is based on the
effect where nuclear spin cross-relaxation after excitation by a radio
pulse depends on the distance between the nuclei. Unlike spin-spin
coupling, NOE propagates through space and does not require that the
atoms are connected by bonds, so it is a true distance measurement
instead of a chemical measurement. Unlike diffraction measurements,
NOESY does not require a crystalline sample, but is done in solution
state and can be applied to substances that are difficult to
crystallize.
Other systems of units
In some systems of units, unlike the current SI system, lengths are fundamental units (for example, wavelengths in the older SI units and bohrs in atomic units) and are not defined by times of transit. Even in such units, however, the comparison
of two lengths can be made by comparing the two transit times of light
along the lengths. Such time-of-flight methodology may or may not be
more accurate than the determination of a length as a multiple of the
fundamental length unit.
Marxist humanism is an international body of thought and political action rooted in an interpretation of the works of Karl Marx. It is an investigation into "what human nature consists of and what sort of society would be most conducive to human thriving" from a critical perspective rooted in Marxist philosophy. Marxist humanists argue that Marx himself was concerned with investigating similar questions.
Marxist humanism was born in 1932 with the publication of Marx's Economic and Philosophic Manuscripts of 1844
and reached a degree of prominence in the 1950s and 1960s. Marxist
humanists contend that there is continuity between the early
philosophical writings of Marx, in which he develops his theory of alienation, and the structural description of capitalist society found in his later works such as Capital. They hold that it is necessary to grasp Marx's philosophical foundations to understand his later works properly.
Contrary to the official dialectical materialism of the Soviet Union and to interpretations of Marx rooted in the structural Marxism of Louis Althusser, Marxist humanists argue that Marx's work was an extension or transcendence of enlightenmenthumanism. Where other Marxist philosophies see Marxism as a natural science,
Marxist humanism reaffirms the doctrine of "man is the measure of all
things" – that humans are essentially different to the rest of the natural order and should be treated so by Marxist theory.
Korsch's book underscores Marx's doctrine of the unity of theory and
practice, viewing socialist revolution as the "realization of philosophy". The most important essay in Lukács's collection introduces the concept of "reification" –
the transformation of human properties into the properties of
man-produced things which have become independent of Man and govern his
life, and conversely the transformation of humans into thing-like
beings. Lukács argues that elements of this concept are implicit in the analysis of commodity fetishism found in Marx's magnum opus Capital. Bourgeois society loses sight of the role of human action in the creation of social meaning. It thinks value is immanent in things and regards persons as commodities.
The writings of Antonio Gramsci
are also extremely important in the development of a humanist
understanding of Marxism. Insisting on Marx's debt to Hegel, Gramsci
sees Marxism as a "philosophy of praxis" and an "absolute historicism" that transcends traditional materialism and traditional idealism.
The first publication of Marx's Economic and Philosophic Manuscripts in 1932 greatly changed the reception of his work. This early work of Marx – written in 1844, when Marx was twenty-five or twenty-six years old – situated his reading of political economy, his relationship to the philosophies of Georg Wilhelm Friedrich Hegel and Ludwig Feuerbach, and his views on communism, within a new theoretical framework. In the Manuscripts, Marx borrows philosophical terminology from Hegel and Feuerbach to posit a critique of capitalist society based in "alienation".
Through his own activity, Man becomes alien from his human
possibilities: to the products of his own activity, to the nature in
which he lives, to other human beings and to himself. The concept is not
merely descriptive, it is a call for de-alienation through radical
change of the world. On publication, the importance of this work was recognized by Marxists such as Raya Dunayevskaya, Herbert Marcuse and Henri Lefebvre. In the period after the Second World War, the texts were translated into Italian and discussed by Galvano Della Volpe. The philosophers Maurice Merleau-Ponty and Jean-Paul Sartre were also drawn to Marxism by the Manuscripts at this time. In 1961, a volume containing an introduction by Erich Fromm was published in the US.
As they provided a missing link between the Hegelian
philosophical humanism of Marx's early writings and the economics of the
later Marx, Marx's Grundrisse were also an important source for Marxist humanism. This 1,000-page collection of Marx's working notes for Capital was first published in Moscow in 1939 and became available in an accessible addition in 1953. Several analysts (most notably Roman Rozdolsky) have commented that the Grundrisse shows the role played by the early Marx's concerns with alienation and the Hegelian concept of dialectic in the formation of his magnum opus.
In the aftermath of the occupation of France and the Second World War, the independent leftist journal Les Temps modernes was founded in 1946. Among its original editorial board were the existentialist philosophers Jean-Paul Sartre and Maurice Merleau-Ponty. While both lent support to the politics and tactics of the French Communist Party and the Soviet Union during this period, they concurrently attempted to formulate a phenomenological and existential Marxism that opposed the Stalinist
version. In their view, the failure of the Western Communist Parties to
lead successful revolutions and the development of an authoritarian
state structure in the Soviet Union were both connected to the "naturalism" and "scientism" of the official orthodox Marxist
theory. Orthodox Marxism is not a theory of revolutionary
self-emancipation but a self-proclaimed science that imposes a direction
upon history from above in the name of irrefutable "iron laws". Against this, Sartre and Merleau-Ponty argued for a subject-centered view of history that emphasized the lived experience of historical actors as the source of cognition.
In 1939, Henri Lefebvre, then a member of the French Communist Party, published Dialectical Materialism. This book, written in 1934–5, advanced a reconstruction of Marx's oeuvre in the light of the 1844 Manuscripts. Lefebvre argued here that Marx's dialectic was not a "Dialectics of Nature" (as set forth by Friedrich Engels) but was instead based on concepts of alienation and praxis. In the wake of the Soviet suppression of the Hungarian Uprising of 1956, Lefebvre – together with Kostas Axelos, Jean Duvignaud, Pierre Fougeyrollas and Edgar Morin – founded the journal Arguments.
This publication became the center of a Marxist humanist critique of
Stalinism. In his theory of alienation, Lefebvre drew not only from the Manuscripts,
but also from Sartre, to proffer a critique that encompassed the styles
of consumption, culture, systems of meaning and language under
capitalism.
Starting in the late 1950s, Roger Garaudy,
for many years the chief philosophical spokesman of the French
Communist Party, offered a humanistic interpretation of Marx stemming
from Marx's early writings that called for dialogue between Communists
and existentialists, phenomenologists and Christians.
The period following the death of Joseph Stalin in 1953 saw a number of movements for liberalization in Eastern Europe. Following Nikita Khrushchev's secret speech, where he denounced Stalinism, Marx's 1844 Manuscripts were used as the basis for a new "socialist humanism" in countries such as Hungary, Poland and Czechoslovakia. The Petofi Circle, which included some of Lukács's disciples, was a center of what was termed "revisionism" in Hungary. In 1959, the Polish writer Leszek Kołakowski
published an article "Karl Marx and the Classical Definition of Truth"
that drew a sharp distinction between the theory of knowledge found in
the works of the young Marx and the theory found in Engels and Lenin. This challenge was taken up by Adam Schaff, a member of the Central Committee of the Polish United Workers' Party, and expanded into an investigation into the persistence of alienation in socialist societies. The Czechoslovak Karel Kosik also began the critique of communist dogmatism that would develop into his Dialectics of the Concrete, and would eventually land him in jail.
This period also saw the formation of a humanist Marxism by Yugoslav philosophers Mihailo Marković and Gajo Petrović that would come to act as the basis of the Praxis School. From 1964 to 1975, this group published a philosophical journal, Praxis, and organized annual philosophical debates on the island of Korčula. They concentrated on themes such as alienation, reification and bureaucracy.
Marxist humanism opposes the philosophy of "dialectical materialism" that was orthodox among the Soviet-aligned Communist Parties. Following the synthesis of Hegel's dialectics and philosophical materialism in Friedrich Engels's Anti-Dühring, the Soviets saw Marxism as a theory not just of society but of reality as a whole. Engels's book is not a work of science, but of what he calls "natural philosophy".
Nonetheless, he claims that discoveries within the sciences tend to
confirm the scientific nature of his theory. This world-view is
instantiated within both the natural and social sciences.
Marxist humanists reject an understanding of society based on
natural science, asserting the centrality and distinctiveness of people
and society. Marxist humanism views Marxist theory as not primarily
scientific but philosophical. Social science is not another natural science and people and society are not instantiations of universal natural processes. Rather, people are subjects – centers of consciousness and values – and science is an embedded part of the totalizing perspective of humanist philosophy. Echoing the inheritance of Marx's thought from German Idealism, Marxist humanism holds that reality does not exist independently of human knowledge, but is partly constituted by it.
Because human social practice has a purposive, transformative
character, it requires a mode of understanding different from the
detached, empirical observation of the natural sciences. A theoretical
understanding of society should instead be based in empathy with or
participation in the social activities it investigates.
Alienation
In line with this, Marxist humanism treats alienation as one of Marxism's central concepts. In his early writings, the young Marx advances a critique of modern society on the grounds that it impedes human flourishing.
His theory of alienation suggests a dysfunctional or hostile relation
between entities that naturally belong in harmony with one another – an artificial separation of one
entity from another with which it had been previously and properly conjoined. The concept has "subjective" and "objective" variants. Alienation is "subjective" when human individuals feel "estranged" or do not feel at home in the modern social world.
Individuals are objectively alienated when they do not develop their
essential human capacities. For Marx, objective alienation is the cause
of subjective alienation: individuals experience their lives as lacking
meaning or fulfilment because society does not promote the deployment of
their human capacities.
Marxist humanism views alienation as the guiding idea of both Marx's early writings and his later works. According to this school of thought, the central concepts of Capital cannot be fully and properly understood without reference to this seminal theme. Communism
is not merely a new socioeconomic formation that will supersede the
present one, but the re-appropriation of Man's life and the abolition of
alienation.
In the state
The earliest appearance of this concept in Marx's corpus is the Critique of Hegel's Philosophy of Right from 1843. Drawing a contrast between the forms of community in the ancient and medieval worlds and the individualism of modern civil society, Marx here characterizes the modern social world as "atomistic".
Modern civil society does not sustain the individual as a member of a
community. Where in medieval society people are motivated by the
interest of their estate, an unimpeded individualism is the principle
that underpins modern social life. Marx's critique does not rest with civil society: he also holds that the modern political state is distinguished by its "abstract" character.
While the state acknowledges the communal dimension of human
flourishing, its existence has a "transcendental remoteness" separate
from the "real life" of civil society. The state resolves the alienation
of the modern world, but in an inadequate manner.
Marx credits Hegel with significant insight into both the basic
structure of the modern social world and its disfigurement by
alienation.
Hegel believes alienation will no longer exist when the social world
objectively facilitates the self-realization of individuals, and
individuals subjectively understand that this is so.
For Hegel, objective alienation is already non-existent, as the modern
social world does facilitate individuals' self-realization. However,
individuals still find themselves in a state of subjective alienation.
Hegel wishes not to reform or change the institutions of the modern
social world, but to change the way in which society is understood by
its members.
Marx shares Hegel's belief that subjective alienation is widespread but
denies that the rational or modern state enables individuals to
actualize themselves. Marx instead takes subjective alienation to
indicate that objective alienation has not been overcome.
The most well-known metaphor in Marx's Critique – that of religion as the opium of the people – is derived from the writings of the theologianBruno Bauer. Bauer's primary concern is religious alienation. Bauer views religion as a division in Man's consciousness.
Man suffers from the illusion that religion exists apart from and
independent of his own consciousness, and that he himself is dependent
on his own creation. Religious beliefs become opposed to consciousness
as a separate power. A religious consciousness cannot exist without this
breaking up or tearing apart of consciousness: religion deprives Man of
his own attributes and places them in a heavenly world. The Gospel narrative contains no historical truth – it is an expression of a transient stage in the historical development of self-consciousness. Christianity
was of service to self-consciousness in awakening a consciousness of
values that belong to every human individual, but it also created a new
servitude.
Self-consciousness makes itself into an object, a thing, loses control
of itself, and feels itself to be nothing before an opposing power.
Since religious belief is the work of a divided mind, it stands
in contradiction to itself: the Gospels contradict each other and the
world; they contain dogmas so far removed from common sense that they can be understood only as mysteries. The God that men worship is a subhuman God – their own imaginary, inflated and distorted reflection. The task of the present phase of human history
is to liberate Man's spirit from the bonds of Christian mythology, free
the state from religion, and thereby restore to Man his alienated essence.
In the Critique, Marx adopts Bauer's criticism of religion and applies this method to other fields. Marx sees Man's various alienations as peels around a genuine center. Religion is at once both the symptom of a deep social malaise and a protest against it. The criticism of religion leads to the criticism of other alienations, which must be dealt with in the same way.
The influence of Bauer follows Marx through all his later criticism:
this is most visible in the many places where Marx establishes an
economic point by reference to a religious analogy.
In the Economic and Philosophic Manuscripts of 1844, Marx further develops his critique of Hegel. Marx here praises Hegel's dialectic
for its view of labor as an alienating process: alienation is an
historical stage that must be passed through for the development and
deployment of essential human powers.
It is an essential characteristic of finite mind (Man) to produce
things, to express itself in objects, to objectify itself in physical
things, social institutions and cultural products. Every objectification
is of necessity an instance of alienation: the produced objects become
alien to the producer.
Humanity creates itself by externalizing its own essence, developing
through a process of alienation alternating with transcendence of that
alienation.
For Hegel, alienation is the state of consciousness as it acquaints itself with the external, objective, phenomenal world. Hegel believes that reality is Spirit
realizing itself. Spirit's existence is constituted only in and through
its own productive activity. In the process of realizing itself, Spirit
produces a world that it initially believes to be external, but
gradually comes to understand is its own production. All that exists is the Absolute Spirit
(Absolute Mind, Absolute Idea or God). The Absolute is not a static or
timeless entity but a dynamic Self, engaged in a cycle of alienation and
de-alienation. Spirit becomes alienated from itself in nature
and returns from its self-alienation through the finite Mind, Man.
Human history is a process of de-alienation, consisting in the constant
growth of Man's knowledge of the Absolute. Conversely, human history is
also the development of the Absolute's knowledge of itself: the Absolute
becomes self-aware through Man.
Man is a natural being and is thus a self-alienated Spirit. But Man is
also an historical being, who can achieve adequate knowledge of the
Absolute, and is thus capable of becoming a de-alienated being.
Marx criticizes Hegel for understanding labor as "abstract mental labour". Hegel equates Man with self-consciousness and sees alienation as constituted by objectivity. Consciousness emancipates itself from alienation by overcoming objectivity, recognizing that what appears as an external object is a projection of consciousness itself.
Hegel sees freedom as consisting in men's becoming fully self-conscious
and understanding that their environment and culture are emanations
from Spirit. Marx rejects the notion of Spirit, believing that Man's
ideas, though important, are by themselves insufficient to explain
social and cultural change.
In Hegel, Man's integration with nature takes places on a spiritual
level and is thus, in Marx's view, an abstraction and an illusion.
In Feuerbach
The main influence on Marx's thinking in this regard is Ludwig Feuerbach, who in his Essence of Christianity
aims to overcome the harm and distress of the separation of individuals
from their essential human nature. Feuerbach believes the alienation of
modern individuals is caused by their holding false beliefs about God.
People misidentify as an objective being what in actuality is a man-made
projection of their own essential predicates.
For Feuerbach, Man is not a self-alienated God; God is self-alienated
Man. God is Man's essence abstracted, absolutized and estranged from
Man.
Man creates the idea of God by gathering the best features of his human
nature – his goodness, knowledge and power – glorifying them, and
projecting them into a beyond.
Man is alienated from himself not because he refuses to recognize
nature as a self-alienated form of God, but because he creates, and puts
above himself, an imagined alien higher being and bows before him as a
slave. Christian belief entails the sacrifice, the practical denial or repression, of essential human characteristics.
Liberation will come when people recognize what God really is and,
through a community that subjects human essence to no alien limitation,
reclaim the goodness, knowledge and power they have projected
heavenward.
This critique extends beyond religion, as Feuerbach argues in his Theses on the Reform of Philosophy
that Hegelian philosophy is itself alienated. Hegel regards alienation
as affecting thought or consciousness and not humanity in its material
being. For Hegel, concrete, finite existence is merely a reflection of a
system of thought or consciousness. Hegel starts and ends with the
infinite. The finite, Man, is present as only a phase in the evolution
of a human spirit, the Absolute. In opposition to this, Feuerbach argues that Man is alienated because he mediates a direct relationship of sensuous intuition to concrete reality through religion and philosophy. By recognizing that his relationship to nature is instead one of immediate unity, Man can attain a "positive humanism" that is more than just a denial of religion.
In work
Following Feuerbach, Marx places the earthly reality of Man in the center of this picture.
Where Hegel sees labor as spiritual activity, Marx sees labor as
physical interchange with nature: in nature, Man creates himself and
creates nature. Where Hegel identifies human essence with
self-consciousness, Marx articulates a concept of species-being (Gattungswesen), according to which Man's essential nature is that of a free producer, freely reproducing his own conditions of life.
Man's nature is to be his own creator, to form and develop
himself by working on and transforming the world outside him in
cooperation with his fellow men. Man should be in control of this
process but in modern conditions Man has lost control of his own
evolution. Where land-ownership is subject to the laws of a market economy, human individuals do not fulfill themselves through productive activity.
A worker's labor, his personal qualities of muscle and brain, his
abilities and aspirations, his sensuous life-activity, appear to him as
things, commodities to be bought and sold like any other.
Much as Bauer and Feuerbach see religion as an alienating invention of
the human mind, so does Marx believe the modern productive process to
reduce the human being to the status of a commodity.
In religion, God holds the initiative and Man is in a state of
dependence. In economics, money moves humans around as though they were
objects instead of the reverse.
Marx claims that human individuals are alienated in four ways:
From their products
From their productive activity
From other individuals
From their own nature.
Firstly, the product of a worker's labor confronts him "as an alien
object that has power over him". A worker has bestowed life on an object
that now confronts him as hostile and alien. The worker creates an
object, which appears to be his property. However, he now becomes its
property.
When he externalizes his life in an object, a worker's life belongs to
the object and not to himself; his nature becomes the attribute of
another person or thing.
Where in earlier historical epochs, one person ruled over another, now
the thing rules over the person, the product over the producer.
Secondly, the worker relates to the process by which this product
is created as something alien that does not belong to him. His work
typically does not fulfill his natural talents and spiritual goals and
is experienced instead as "emasculation".
Thirdly, the worker experiences mutual estrangement – alienation
from other individuals. Each individual regards others as a means to his
own end. Concern for others exists mainly in the form of a calculation
about the effect those others have on his own narrow self-interest.
Fourthly, the worker experiences self-estrangement: alienation
from his human nature. Because work is a means to survival only, the
worker does not fulfill his human need for self-realization in
productive activity.
The worker is only at ease in his animal functions of eating, drinking
and procreating. In his distinctly human functions, he is made to feel
like an animal. Modern labor turns the worker's essence as a producer into something "alien".
Marx mentions other features of alienated labor: overwork, or the
amount of time that the modern worker has to spend engaged in
productive activity; "more and more one-sided" development of the
worker, or the lack of variety in his activity; the machine-like
character of labor and the intellectual stunting that results from the
neglect of mental skills in productive activity.
The capitalist
does not escape the process of alienation. Where the worker is reduced
to an animal condition, the capitalist is reduced to an abstract
money-power. His human qualities are transformed into a personification
of the power of money.
In contrast to this negative account of alienated labor, Marx's Notes on James Mill offer a positive description of unalienated labor.
Marx here claims that in self-realizing work, one's personality would
be made objective in one's product and that one would enjoy
contemplating that feature in the object one produces. As one has expressed one's talents and abilities in the productive process, the activity is authentic to one's character. It ceases to be an activity one loathes.
Marx further claims that one gains immediate satisfaction from the use
and enjoyment of one's product – the satisfaction arising from the
knowledge of having produced an object that corresponds to the needs of
another human being.
One can be said to have created an object that corresponds to the needs
of another's essential nature. One's productive activity is a mediator
between the needs of another person and the entire species. Because
individuals play this essential role in the affirmation of each other's
nature, Marx suggests that this confirms the "communal" character of
human nature.
To overcome alienation and allow humankind to realize its
species-being, it is not enough, as Hegel and Feuerbach believe, to
simply grasp alienation. It is necessary to transform the world that
engenders alienation: the wage-labor system must be transcended, and the
separation of the laborer from the means of labor abolished. This is
not the task of a solitary philosophical critic, but of class struggle.
The historic victory of capitalism in the middle of the 19th century
has made alienation universal, since everything enters in to the cycle
of exchange, and all value is reduced to commodity value. In a developed capitalist society, all forms of alienation are comprised in the worker's relation to production. All possibilities of the worker's very being are linked to the class struggle against capital. The proletariat, which owns nothing buts its labor power, occupies a position radically different to all other classes. The liberation of the working class will therefore be the liberation of mankind.
This emancipation is not simply the abolition of private property.
Marx differentiates his communism from the primitive communism that
seeks to abolish everything that cannot be the property of all. For
Marx, this would be the generalization of alienation and the abolition
of talent and individuality – tantamount to abolishing civilization.
Marx instead sees communism as a positive abolition of private
property, where Man recovers his own species-being, and Man's activity
is no longer opposed to him as something alien. This is a direct
affirmation of humanity: just as atheism
ceases to be significant when the affirmation of Man is no longer
dependent on the negation of God, communism is a direct affirmation of
Man independent of the negation of private property.
In division of labor
In the German Ideology, Marx and his collaborator Friedrich Engels provide an account of alienation as deriving from division of labor. Alienation is said to arise from improvements in tools, which in turn lead to commerce. Man transforms objects produced by Man into commodities – vehicles for abstract exchange-value. Division of labor and exchange relations subsume individuals in classes,
subordinating them to forces to which they have no choice but to
comply. Alienated processes appear to individuals as if they were
natural processes.
Physical and mental work are also separated from each other, giving
rise to self-deluded ideologists who believe their thoughts have an
inherent validity and are not dictated by social needs.
Marx and Engels here attack Feuerbach for advancing an
"essentialist" account of human nature that reduces real historical men
to a philosophical category. They argue that it is not a philosophical
concept ("Man") that makes history, but real individuals in definite
historical conditions.
In economics
In the Grundrisse, Marx continues his discussion of the problem of alienation in the context of political economy. Here, the central themes of the 1844 Manuscripts are dealt with in a much more sophisticated manner. Marx builds on his earlier conception of Man as a productive, object-creating being.
The concepts found in Marx's earlier work – alienation,
objectification, appropriation, Man's dialectical relationship to nature
and his generic or social nature – all recur in the Grundrisse.
Marx views political economy as a reflection of the alienated
consciousness of bourgeois society. It mystifies human reality by
transforming the production of commodities into "objective" laws which
independently regulate human activity. The human subject is made into
the object of his own products. A key difference between the Grundrisse and the Manuscripts is Marx's starting with an analysis of production, rather than the mechanisms of exchange. The production of objects must be emancipated from the alienated form given to it by bourgeois society. Moreover, Marx no longer says that what a worker sells is his labor, but rather his labor-power.
The discussion of alienation in the Grundrisse is also more firmly rooted in history. Marx argues that alienation did not exist in earlier periods – primitive communism – where wealth was still conceived as residing in natural objects and not man-made commodities.
However, such societies lacked the creation of objects by purposive
human activity. They cannot be a model for a fully-developed communism
that realizes human potentiality. Capital is an "alienating" force, but it has fulfilled a very positive function. It has developed the productive forces enormously, has replaced natural needs by ones historically created and has given birth to a world market. Nonetheless, Marx sees capitalism as transitory: free competition will inevitably hinder the development of capitalism.
The key to understanding the ambivalent nature of capitalism is the notion of time.
On the one hand, the profits of capitalism are
built on the creation of surplus work-time, but on the other the wealth
of capitalism has emancipated Man from manual labor and provided
him increasing access to free time. Marx criticizes political economy for its division of Man's time between work and leisure.
This argument misunderstands the nature of human activity. Labor is not
naturally coercive. Rather, the historical conditions in which labor is
performed frustrate human spontaneity. Work should not be a mere means for Man's existence, it should become the very contents of his life.
In property
The Grundrisse also continues the discussion of private property that Marx began in the German Ideology.
Marx's views on property stand in contrast to those of Hegel, who
believes that property realizes human personality through
objectification in the external world.
For Marx, property is not the realization of personality but its
negation. The possession of property by one person necessarily entails
its non-possession by another. Property is thus not to be assured to
all, but to be abolished.
The first form of property, according to Marx, is tribal
property. Tribal property originates in the capacity of a human group to
gain possession of land. Tribal property precedes the existence of
permanent settlement and agriculture.
The act of possession is made possible by the prior existence of group
cohesion, i.e. a social, tribal organization. Thus, property does not
pre-date society but results from it. An individual's relation to
property is mediated through membership of the group. It is a form of
unalienated property that realizes Man's positive relationship to his
fellow tribesmen.
However, this relationship limits the individual's power to establish a
self-interest distinct from the general interest of society. This primitive type of common ownership disappears with the development of agriculture.
The unity of the individual and society is preserved by more complex societies in two distinct forms: oriental despotism and the classical polis. In oriental despotism, the despot personifies society – all property belongs to him. In the polis,
the basic form of property is public. Economic activity depends on
community-oriented considerations. Political rights depend on
participation in common ownership of land. Agriculture is considered
morally and publicly superior to commerce. Public agricultural policy is
judged on its ability to produce more patriotic citizens, rather than
economic considerations. Alienation between the public and private sphere does not exist in the polis.
Marx does not idealize the polis or call for its restoration. Its foundation on naturalistic matter is specific and limited.
Marx opposes to this the universality of capital. Capital is
objectified human labor: on the one hand it indicates hidden human
potentialities but on the other its appearance is accompanied by
alienation.
Capitalism develops a kind of property free from social limitations and
considerations. Concurrently, capitalism ends individual private
property as traditionally conceived, in that it divorces the producer
from the ownership of the means of production.
Such property is at the exclusive disposition of its owner. Yet, the
development of capitalist society also entails more complex production,
requiring combined efforts that cannot be satisfied by individual
property.
In commodity fetishism
To make a fetish of something, or fetishize it, is to invest it with powers it does not in itself have. In Capital. Volume 1,
Marx argues that the false consciousness of human beings in relation to
their social existence arises from the way production is organized in
commodity society. He calls this illusion "commodity fetishism".
The production of a product as a value is a phenomenon specific to market economies. Whereas in other economies, products have only use-value, in market economies products have both use-value and exchange-value.
Labor that produces use-value is concrete, or qualitatively
differentiated: tailoring, weaving, mining, etc. Labor productive of
exchange-value is abstract, just a featureless proportion of the total
labor of society.
In such production, the labor of persons takes the form of the
exchange-value of things. The time taken to produce a commodity takes
the form of the exchange-value of the commodity.
The measure that originally relates to the life process itself is thus
introduced into the products of labor. The mutual relations of humans as
exchangers of goods take on the form of relations between objects.
These objects appear to have mysterious qualities which of themselves
make them valuable, as though value were a natural, physical property of
things.
While commodities do indeed have exchange-value, they do not have this
value autonomously, but as a result of the way labor is organized. By failing to understand this process wherein social relations
masquerade as things or relations between things, humans involuntarily
accept that their own qualities, abilities and efforts do not belong to
themselves but are inherent in the objects they create.
The labor bestowed upon commodities is what constitutes their
value, but it does not appear to do so. Commodity fetishism, or the
appearance that the products of labor have value in and of themselves,
arises from the particular social form within which commodity production
takes place – the market society. Here, the social character of
production is expressed only in exchange, not in production itself. In other societies – primitive communism, the patriarchaltribe, feudalism,
the future communist society – producers are directly integrated with
one another by custom, directive, or plan. In commodity society,
producers connect mediately, not as producers but as marketeers.
Their products do not have a social form prior to their manifestations
as commodities, and it is the commodity form alone that connects
producers.
While the relations between commodities are immediately social, the
relations between producers are only indirectly so. Because persons lack
direct social relations, it appears to them that they labor because
their products have value. However, their products in fact have value
because labor has been bestowed on them. Men relate to each other
through the value they create. This value regulates their lives as
producers, yet they do not recognize their own authorship of this value.
Marx does not use the term alienation here, but the description is the same as in his earlier works, as is the analogy with religion that he owes to Feuerbach.
In religious fetishism an activity of thought, a cultural process,
vests an object with apparent power. While the object does not really
acquire the power mentally referred to it, if a culture makes a fetish
of an object, its members come to perceive it as endowed with the power.
Fetishism is the inability of human beings to see their products for
what they are. Rather than wielding his human power, Man becomes
enslaved by his own works: political institutions appear to have
autonomy, turning them into instruments of oppression; scientific
development and the organization of labor, improved administration and
multiplication of useful products are transformed into quasi-natural
forces and turned against Man.
A particular expression of commodity fetishism is the reification
of labor power, in which human persons appear in the context of labor
as commodities bought and sold on the market according to the laws of
value. Wage-labor, wherein a class of wage-earners sells its labor power to an owner of the means of production, is the characteristic feature of capitalism. Capitalist profit
finds it origin in there being a commodity whose use-value is a source
of value, but which creates exchange-value when its use-value is
consumed. This commodity is labor power. Like any other commodity, the
value of labor power is determined by the amount of labor time necessary
to reproduce it. Labor power is reproduced through maintaining the
worker in a condition in which he is able to work and to rear a fresh
generation of workers. The value of labor power is thus the value of the
products necessary to keep the laborer and his children alive and
able-bodied. This is determined not by the mere physiological minimum
but also by needs that vary historically.
The use-value of labor power consists in the fact that it creates
an exchange-value greater than its own. A capitalist pays for the right
to use a worker's labor power over the course of a day, yet the working day
is much longer than necessary to keep a worker in an active state. If
the wages earned over the first half of the worker's day correspond to
the value necessary to reproduce his labor power, those earned over the
second half amount to unrequited labor. This generates an excess of
value much larger than the cost of the worker's maintenance. This is
what Marx calls "surplus value".
The commodity character of labor power is the social nexus on which
capitalist production is built. In this situation, a man functions as a
thing. He is reduced to a state where it is his exchange-value, and not
his personality, that counts for anything.
Praxis
Marx's theory of alienation is intimately linked to a theory of praxis. Praxis is Man's conscious,
autonomous, creative, self-reflective shaping of changing historical
conditions. Marx understands praxis as both a tool for changing the
course of history and a criterion for the evaluation of history. Marxist humanism views Man as in essence a being of praxis – a self-conscious creature who can appropriate for his own use the whole realm of inorganic nature –
and Marx's philosophy as in essence a "philosophy of praxis" – a theory
that demands the act of changing the world while also participating in
this act.
Naturalism is the view that Man is part of the system of nature. Marx sees Man as an objective, natural being – the product of a long biologicalevolution.
Nature is that which is opposed to Man, yet it is through nature that
Man satisfies the needs and drives that constitute his essence. Man
needs objects that are independent of him to express his objective
nature.
Humanism is the view that Man is a being of praxis who both changes nature and creates himself.
It is not the simple attribute of consciousness that makes man
peculiarly human, but rather the unity of consciousness and practice –
the conscious objectification of human powers and needs in sensuous
reality.
Marx distinguishes the free, conscious productive activity of human
beings from the unconscious, compulsive production of animals. Praxis is an activity unique to Man: while other animals produce, they produce only what is immediately necessary.
Man, on the other hand, produces universally and freely. Man is able to
produce according to the standard of any species and at all times knows
how to apply an intrinsic standard to the object he produces. Man thus creates according to the laws of beauty.
The starting point for Man's self-development is the wealth of his own
capacities and needs that he himself creates. Man's evolution enters
the stage of human history when, through praxis, he acquires more and more control of blind natural forces and produces a humanized natural environment.
As human knowledge
Since
Man's basic characteristic is his labor – his commerce with nature in
which he is both active and passive – the traditional problems of epistemology must be looked at from a new standpoint.
The role of work or labor in the cognitive process is a dominant
epistemological theme in Marx's thought. Marx understands human
knowledge to be mediated through praxis or intentional human agency. The relations between Man and his environment are relations between the species and the objects of its need.
Practical usefulness is a factor in the definition of truth: a
judgement or opinion's usefulness is not merely a tool for establishing
its truth, but is what creates its truth.
In his Theses on Feuerbach, Marx admonishes the materialism of Ludwig Feuerbach for its contemplative theory of knowledge. Marx holds that Feuerbach's mistake lies with his failure to envisage objects
as sensuous, practical, human activity. For Marx, perception is itself a
component of Man's practical relationship to the world. The object of
Man's perception is not "given" by indifferent nature, but is a
humanized object, conditioned by human needs and efforts.
Criticism
As the terminology of alienation does not appear in a prominent manner in Marx's later works such as Capital, Marxist humanism has been quite controversial within Marxist circles. The tendency was attacked by the Italian Western MarxistGalvano Della Volpe and by Louis Althusser, the French Structuralist Marxist.
Althusser criticizes Marxist humanists for not recognizing what he
considers to be the fundamental dichotomy between the theory of the "Young Marx" and that of the "Mature Marx". Althusser holds that Marx's thought is marked by a radical epistemological break, to have occurred in 1845 – The German Ideology being the earliest work to betray the discontinuity. For Althusser, the humanism of Marx's early writings – an ethical theory – is fundamentally incongruous with the "scientific" theory he argues is to be found in Marx's later works.
In his view, the Mature Marx presents the social relations of
capitalism as relations within and between structures; individuals or
classes have no role as the subjects of history.
Althusser believes socialist humanism to be an ethical and thus ideological phenomenon. Humanism is a bourgeoisindividualist philosophy that ascribes a universal essence of Man that is the attribute of each individual and through which there is potential for authenticity and common human purpose.
This essence does not exist: it is a formal structure of thought whose
content is determined by the dominant interests of each historical
epoch.
The argument of socialist humanism rests on a similar moral and ethical
basis. Hence, it reflects the reality of discrimination and
exploitation that gives rise to it but never truly grasps this reality
in thought. Marxist theory must go beyond this to a scientific analysis
that directs to underlying forces such as economic relations and social
institutions. For this reason, Althusser sympathized with the criticisms of socialist humanism made by the Chinese Communist Party, which condemned the tendency as "revisionism" and "phony communism".
Althusser sees Marxist theory as primarily science and not
philosophy but he does not adhere to Engels's "natural philosophy". He
claims that the philosophy implicit in Marxism is an epistemology (theory of knowledge) that sees science as "theoretical practice" and philosophy as the "theory of theoretical practice".
However, he later qualifies this by claiming that Marxist philosophy,
unlike Marxist science, has normative and ideological elements: Marxist philosophy is "politics in the field of theory" and "class struggle in theory".
Althusser is critical of what he perceives to be a reliance among Marxist humanists on Marx's 1844 Manuscripts,
which Marx did not write for publication. Marxist humanists strongly
dispute this: they hold that the concept of alienation is recognizable
in Marx's mature work even when the terminology has been abandoned. Teodor Shanin and Raya Dunayevskaya
assert that not only is alienation present in the late Marx, but that
there is no meaningful distinction to be made between the "young Marx"
and "mature Marx". The Marxist humanist activist Lilia D. Monzó states
that "Marxist-Humanism, as developed by Raya Dunayevskaya, considers the
totality of Marx's works, recognizing that his early work in the Economic and Philosophic Manuscripts of 1844, was profoundly humanist and led to and embeds his later works, including Capital."
Contra Althusser, Leszek Kołakowski argues that although it is true that in Capital
Marx treats human individuals as mere embodiments of functions within a
system of relations apparently possessed of its own dynamic and created
independently, he does so not as a general methodical rule, but as a
critique of the dehumanizing nature of exchange-value.
When Marx and Engels present individuals as non-subjects subordinated
to structures that they unwittingly support, their intention is to
illuminate the absence of control that persons have in bourgeois
society. Marx and Engels do not see the domination of alien forces over
humans as an eternal truth, but rather as the very state of affairs to
be ended by the overthrow of capitalism.
Marxist humanists
Notable thinkers associated with Marxist humanism include:
Kevin B. Anderson (born 1948), American social theorist and activist.
Walter Benjamin (1892–1940), German-Jewish Marxist literary critic, essayist, translator, and philosopher.
John Berger (1926–2017), English art critic, novelist, painter and author.
Franklin Rosemont (1943–2009), American writer, artist, historian, and activist.
Wang Ruoshui (1926–2002), Chinese journalist and philosopher.
Jean-Paul Sartre
(1905–1980), French existentialist philosopher, playwright, novelist,
screenwriter, political activist, biographer, and literary critic.
Cyril Smith (1929–2008), British lecturer of statistics at the London School of Economics, socialist, and revolutionary humanist.
Ivan Sviták (1925–1994), Czech social critic and aesthetic theorist.
E. P. Thompson (1924–1993), English historian, socialist and peace campaigner.
Raymond Williams (1921–1988), Welsh literary theorist, co-founder of cultural studies.
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