From Wikipedia, the free encyclopedia
In
philosophy,
systems theory,
science, and
art,
emergence
occurs when an entity is observed to have properties its parts do not
have on their own, properties or behaviors which emerge only when the
parts interact in a wider whole.
Emergence plays a central role in theories of integrative levels and of complex systems. For instance, the phenomenon of life as studied in biology is an emergent property of chemistry, and many psychological phenomena are known to emerge from underlying neurobiological processes.
In philosophy, theories that emphasize emergent properties have been called emergentism.
In philosophy
Philosophers often understand emergence as a claim about the etiology of a system's
properties. An emergent property of a system, in this context, is one
that is not a property of any component of that system, but is still a
feature of the system as a whole. Nicolai Hartmann (1882-1950), one of the first modern philosophers to write on emergence, termed this a categorial novum (new category).
Definitions
This concept of emergence dates from at least the time of Aristotle. The many scientists and philosophers
who have written on the concept include John Stuart Mill (Composition of Causes, 1843) and Julian Huxley (1887-1975).
The philosopher G. H. Lewes coined the term "emergent", writing in 1875:
Every resultant is either a sum or a difference of the
co-operant forces; their sum, when their directions are the same – their
difference, when their directions are contrary. Further, every
resultant is clearly traceable in its components, because these are homogeneous and commensurable.
It is otherwise with emergents, when, instead of adding measurable
motion to measurable motion, or things of one kind to other individuals
of their kind, there is a co-operation of things of unlike kinds. The
emergent is unlike its components insofar as these are incommensurable,
and it cannot be reduced to their sum or their difference.
In 1999 economist Jeffrey Goldstein provided a current definition of emergence in the journal Emergence.
Goldstein initially defined emergence as: "the arising of novel and
coherent structures, patterns and properties during the process of self-organization in complex systems".
In 2002 systems scientist Peter Corning described the qualities of Goldstein's definition in more detail:
The common characteristics are: (1) radical novelty
(features not previously observed in systems); (2) coherence or
correlation (meaning integrated wholes that maintain themselves over
some period of time); (3) A global or macro "level" (i.e. there is some
property of "wholeness"); (4) it is the product of a dynamical process
(it evolves); and (5) it is "ostensive" (it can be perceived).
Corning suggests a narrower definition, requiring that the components
be unlike in kind (following Lewes), and that they involve division of labor between these components. He also says that living systems (comparably to the game of chess), while emergent, cannot be reduced to underlying laws of emergence:
Rules, or laws, have
no causal efficacy; they do not in fact 'generate' anything. They serve
merely to describe regularities and consistent relationships in nature.
These patterns may be very illuminating and important, but the
underlying causal agencies must be separately specified (though often
they are not). But that aside, the game of chess illustrates ... why any
laws or rules of emergence and evolution are insufficient. Even in a
chess game, you cannot use the rules to predict 'history' – i.e., the
course of any given game. Indeed, you cannot even reliably predict the
next move in a chess game. Why? Because the 'system' involves more than
the rules of the game. It also includes the players and their unfolding,
moment-by-moment decisions among a very large number of available
options at each choice point. The game of chess is inescapably
historical, even though it is also constrained and shaped by a set of
rules, not to mention the laws of physics. Moreover, and this is a key
point, the game of chess is also shaped by teleonomic, cybernetic, feedback-driven influences. It is not simply a self-ordered process; it involves an organized, 'purposeful' activity.
Strong and weak emergence
Usage
of the notion "emergence" may generally be subdivided into two
perspectives, that of "weak emergence" and "strong emergence". One paper
discussing this division is Weak Emergence, by philosopher Mark Bedau.
In terms of physical systems, weak emergence is a type of emergence in
which the emergent property is amenable to computer simulation or
similar forms of after-the-fact analysis (for example, the formation of a
traffic jam, the structure of a flock of starlings in flight or a
school of fish, or the formation of galaxies). Crucial in these
simulations is that the interacting members retain their independence.
If not, a new entity is formed with new, emergent properties: this is
called strong emergence, which it is argued cannot be simulated or
analysed.
Some common points between the two notions are that emergence
concerns new properties produced as the system grows, which is to say
ones which are not shared with its components or prior states. Also, it
is assumed that the properties are supervenient rather than metaphysically primitive.
Weak emergence describes new properties arising in systems as a
result of the interactions at an elemental level. However, Bedau
stipulates that the properties can be determined only by observing or
simulating the system, and not by any process of a reductionist analysis. As a consequence the emerging properties are scale dependent:
they are only observable if the system is large enough to exhibit the
phenomenon. Chaotic, unpredictable behaviour can be seen as an emergent
phenomenon, while at a microscopic scale the behaviour of the
constituent parts can be fully deterministic.
Bedau notes that weak emergence is not a universal metaphysical solvent, as the hypothesis that consciousness is weakly emergent would not resolve the traditional philosophical questions
about the physicality of consciousness. However, Bedau concludes that
adopting this view would provide a precise notion that emergence is
involved in consciousness, and second, the notion of weak emergence is
metaphysically benign.
Strong emergence describes the direct causal action of a high-level system upon its components; qualities produced this way are irreducible to the system's constituent parts.
The whole is other than the sum of its parts. An example from physics
of such emergence is water, which appears unpredictable even after an
exhaustive study of the properties of its constituent atoms of hydrogen
and oxygen.
It is argued then that no simulation of the system can exist, for such a
simulation would itself constitute a reduction of the system to its
constituent parts.
Rejecting the distinction
However,
biologist Peter Corning has asserted that "the debate about whether or
not the whole can be predicted from the properties of the parts misses
the point. Wholes produce unique combined effects, but many of these
effects may be co-determined by the context and the interactions between
the whole and its environment(s)". In accordance with his Synergism Hypothesis, Corning also stated: "It is the synergistic effects produced by wholes that are the very cause of the evolution of complexity in nature." Novelist Arthur Koestler used the metaphor of Janus
(a symbol of the unity underlying complements like open/shut,
peace/war) to illustrate how the two perspectives (strong vs. weak or holistic vs. reductionistic) should be treated as non-exclusive, and should work together to address the issues of emergence. Theoretical physicist PW Anderson states it this way:
The ability to reduce everything to simple fundamental
laws does not imply the ability to start from those laws and reconstruct
the universe. The constructionist hypothesis breaks down when
confronted with the twin difficulties of scale and complexity. At each
level of complexity entirely new properties appear. Psychology is not
applied biology, nor is biology applied chemistry. We can now see that
the whole becomes not merely more, but very different from the sum of
its parts.
Viability of strong emergence
Some
thinkers question the plausibility of strong emergence as contravening
our usual understanding of physics. Mark A. Bedau observes:
Although strong emergence is logically possible, it is
uncomfortably like magic. How does an irreducible but supervenient
downward causal power arise, since by definition it cannot be due to the
aggregation of the micro-level potentialities? Such causal powers would
be quite unlike anything within our scientific ken. This not only
indicates how they will discomfort reasonable forms of materialism.
Their mysteriousness will only heighten the traditional worry that
emergence entails illegitimately getting something from nothing.
Strong emergence can be criticized for being causally overdetermined.
The canonical example concerns emergent mental states (M and M∗) that
supervene on physical states (P and P∗) respectively. Let M and M∗ be
emergent properties. Let M∗ supervene on base property P∗. What happens
when M causes M∗? Jaegwon Kim says:
In our schematic example above, we concluded that M
causes M∗ by causing P∗. So M causes P∗. Now, M, as an emergent, must
itself have an emergence base property, say P. Now we face a critical
question: if an emergent, M, emerges from basal condition P, why cannot P
displace M as a cause of any putative effect of M? Why cannot P do all
the work in explaining why any alleged effect of M occurred? If
causation is understood as nomological (law-based) sufficiency, P, as
M's emergence base, is nomologically sufficient for it, and M, as P∗'s
cause, is nomologically sufficient for P∗. It follows that P is
nomologically sufficient for P∗ and hence qualifies as its cause…If M is
somehow retained as a cause, we are faced with the highly implausible
consequence that every case of downward causation involves
overdetermination (since P remains a cause of P∗ as well). Moreover,
this goes against the spirit of emergentism in any case: emergents are
supposed to make distinctive and novel causal contributions.
If M is the cause of M∗, then M∗ is overdetermined because M∗ can
also be thought of as being determined by P. One escape-route that a
strong emergentist could take would be to deny downward causation.
However, this would remove the proposed reason that emergent mental
states must supervene on physical states, which in turn would call physicalism into question, and thus be unpalatable for some philosophers and physicists.
Meanwhile, others have worked towards developing analytical evidence of strong emergence. In 2009, Gu et al. presented a class of physical systems that exhibits non-computable macroscopic properties.
More precisely, if one could compute certain macroscopic properties of
these systems from the microscopic description of these systems, then
one would be able to solve computational problems known to be
undecidable in computer science. Gu et al. concluded that
Although macroscopic concepts are essential for
understanding our world, much of fundamental physics has been devoted to
the search for a 'theory of everything', a set of equations that
perfectly describe the behavior of all fundamental particles. The view
that this is the goal of science rests in part on the rationale that
such a theory would allow us to derive the behavior of all macroscopic
concepts, at least in principle. The evidence we have presented suggests
that this view may be overly optimistic. A 'theory of everything' is
one of many components necessary for complete understanding of the
universe, but is not necessarily the only one. The development of
macroscopic laws from first principles may involve more than just
systematic logic, and could require conjectures suggested by
experiments, simulations or insight.
Emergence and interaction
Emergent
structures are patterns that emerge via the collective actions of many
individual entities. To explain such patterns, one might conclude, per Aristotle,
that emergent structures are other than the sum of their parts on the
assumption that the emergent order will not arise if the various parts
simply interact independently of one another. However, there are those
who disagree.
According to this argument, the interaction of each part with its
immediate surroundings causes a complex chain of processes that can lead
to order in some form. In fact, some systems in nature are observed to
exhibit emergence based upon the interactions of autonomous parts, and
some others exhibit emergence that at least at present cannot be reduced
in this way. In particular renormalization methods in theoretical physics enable scientists to study systems that are not tractable as the combination of their parts.
Objective or subjective quality
Crutchfield regards the properties of complexity and organization of any system as subjective qualities determined by the observer.
Defining structure and detecting the emergence of
complexity in nature are inherently subjective, though essential,
scientific activities. Despite the difficulties, these problems can be
analysed in terms of how model-building observers infer from
measurements the computational capabilities embedded in non-linear
processes. An observer’s notion of what is ordered, what is random, and
what is complex in its environment depends directly on its computational
resources: the amount of raw measurement data, of memory, and of time
available for estimation and inference. The discovery of structure in an
environment depends more critically and subtly, though, on how those
resources are organized. The descriptive power of the observer’s chosen
(or implicit) computational model class, for example, can be an
overwhelming determinant in finding regularity in data.
On the other hand, Peter Corning
argues: "Must the synergies be perceived/observed in order to qualify
as emergent effects, as some theorists claim? Most emphatically not. The
synergies associated with emergence are real and measurable, even if
nobody is there to observe them."
The low entropy
of an ordered system can be viewed as an example of subjective
emergence: the observer sees an ordered system by ignoring the
underlying microstructure (i.e. movement of molecules or elementary
particles) and concludes that the system has a low entropy.
On the other hand, chaotic, unpredictable behaviour can also be seen as
subjective emergent, while at a microscopic scale the movement of the
constituent parts can be fully deterministic.
In religion, art and humanities
In religion, emergence grounds expressions of religious naturalism and syntheism in which a sense of the sacred is perceived in the workings of entirely naturalistic processes by which more complex forms arise or evolve from simpler forms. Examples are detailed in The Sacred Emergence of Nature by Ursula Goodenough & Terrence Deacon and Beyond Reductionism: Reinventing the Sacred by Stuart Kauffman, both from 2006, and in Syntheism – Creating God in The Internet Age by Alexander Bard & Jan Söderqvist from 2014. An early argument (1904–05) for the emergence of social formations, in part stemming from religion, can be found in Max Weber's most famous work, The Protestant Ethic and the Spirit of Capitalism.
Recently, the emergence of a new social system is linked with the
emergence of order from nonlinear relationships among multiple
interacting units, where multiple interacting units are individual
thoughts, consciousness, and actions.
In art, emergence is used to explore the origins of novelty,
creativity, and authorship. Some art/literary theorists (Wheeler, 2006; Alexander, 2011)
have proposed alternatives to postmodern understandings of "authorship"
using the complexity sciences and emergence theory. They contend that
artistic selfhood and meaning are emergent, relatively objective
phenomena. Michael J. Pearce has used emergence to describe the experience of works of art in relation to contemporary neuroscience. Practicing artist Leonel Moura, in turn, attributes to his "artbots" a real, if nonetheless rudimentary, creativity based on emergent principles.
In literature and linguistics, the concept of emergence has been
applied in the domain of stylometry to explain the interrelation between
the syntactical structures of the text and the author style (Slautina,
Marusenko, 2014).
In international development, concepts of emergence have been used within a theory of social change termed SEED-SCALE
to show how standard principles interact to bring forward
socio-economic development fitted to cultural values, community
economics, and natural environment (local solutions emerging from the
larger socio-econo-biosphere). These principles can be implemented
utilizing a sequence of standardized tasks that self-assemble in individually specific ways utilizing recursive evaluative criteria.
In postcolonial studies, the term "Emerging Literature" refers to
a contemporary body of texts that is gaining momentum in the global
literary landscape (v. esp.: J.M. Grassin, ed. Emerging Literatures,
Bern, Berlin, etc. : Peter Lang, 1996). By opposition, "emergent
literature" is rather a concept used in the theory of literature.
Emergent properties and processes
An emergent behavior or emergent property can appear when a number of simple entities
(agents) operate in an environment, forming more complex behaviors as a
collective. If emergence happens over disparate size scales, then the
reason is usually a causal relation across different scales. In other
words, there is often a form of top-down feedback in systems with
emergent properties. The processes causing emergent properties may occur
in either the observed or observing system, and are commonly
identifiable by their patterns of accumulating change, generally called
'growth'. Emergent behaviours can occur because of intricate causal
relations across different scales and feedback, known as interconnectivity.
The emergent property itself may be either very predictable or
unpredictable and unprecedented, and represent a new level of the
system's evolution. The complex behaviour or properties are not a
property of any single such entity, nor can they easily be predicted or
deduced from behaviour in the lower-level entities. The shape and behaviour of a flock of birds or school of fish are good examples of emergent properties.
One reason emergent behaviour is hard to predict is that the number of interactions
between a system's components increases exponentially with the number
of components, thus allowing for many new and subtle types of behaviour
to emerge. Emergence is often a product of particular patterns of
interaction. Negative feedback introduces constraints that serve to fix structures or behaviours. In contrast, positive feedback
promotes change, allowing local variations to grow into global
patterns. Another way in which interactions lead to emergent properties
is dual-phase evolution.
This occurs where interactions are applied intermittently, leading to
two phases: one in which patterns form or grow, the other in which they
are refined or removed.
On the other hand, merely having a large number of interactions
is not enough by itself to guarantee emergent behaviour; many of the
interactions may be negligible or irrelevant, or may cancel each other
out. In some cases, a large number of interactions can in fact hinder
the emergence of interesting behaviour, by creating a lot of "noise" to
drown out any emerging "signal"; the emergent behaviour may need to be
temporarily isolated from other interactions before it reaches enough
critical mass to self-support. Thus it is not just the sheer number of
connections between components which encourages emergence; it is also
how these connections are organised. A hierarchical organisation is one
example that can generate emergent behaviour (a bureaucracy may behave
in a way quite different from the individual departments of that
bureaucracy); but emergent behaviour can also arise from more
decentralized organisational structures, such as a marketplace. In some
cases, the system has to reach a combined threshold of diversity,
organisation, and connectivity before emergent behaviour appears.
Unintended consequences and side effects are closely related to emergent properties. Luc Steels
writes: "A component has a particular functionality but this is not
recognizable as a subfunction of the global functionality. Instead a
component implements a behaviour whose side effect contributes to the
global functionality ... Each behaviour has a side effect and the sum of
the side effects gives the desired functionality".
In other words, the global or macroscopic functionality of a system
with "emergent functionality" is the sum of all "side effects", of all
emergent properties and functionalities.
Systems with emergent properties or emergent structures may appear to defy entropic principles and the second law of thermodynamics,
because they form and increase order despite the lack of command and
central control. This is possible because open systems can extract
information and order out of the environment.
Emergence helps to explain why the fallacy of division is a fallacy.
Emergent structures in nature
Ripple patterns in a
sand dune created by wind or water is an example of an emergent structure in nature.
Giant's Causeway in Northern Ireland is an example of a complex emergent structure.
Emergent structures can be found in many natural phenomena, from the
physical to the biological domain. For example, the shape of weather
phenomena such as hurricanes are emergent structures. The development and growth of complex, orderly crystals, as driven by the random motion of water molecules within a conducive natural environment, is another example of an emergent process, where randomness can give rise to complex and deeply attractive, orderly structures.
Water crystals forming on glass demonstrate an emergent,
fractal process occurring under appropriate conditions of temperature and humidity.
However, crystalline structure and hurricanes are said to have a self-organizing phase.
It is useful to distinguish three forms of emergent structures. A first-order emergent structure occurs as a result of shape interactions (for example, hydrogen bonds in water molecules lead to surface tension). A second-order
emergent structure involves shape interactions played out sequentially
over time (for example, changing atmospheric conditions as a snowflake
falls to the ground build upon and alter its form). Finally, a third-order emergent structure is a consequence of shape, time, and heritable instructions. For example, an organism's genetic code affects the form of the organism's systems in space and time.
Nonliving, physical systems
In physics,
emergence is used to describe a property, law, or phenomenon which
occurs at macroscopic scales (in space or time) but not at microscopic
scales, despite the fact that a macroscopic system can be viewed as a
very large ensemble of microscopic systems.
An emergent property need not be more complicated than the
underlying non-emergent properties which generate it. For instance, the
laws of thermodynamics
are remarkably simple, even if the laws which govern the interactions
between component particles are complex. The term emergence in physics
is thus used not to signify complexity, but rather to distinguish which
laws and concepts apply to macroscopic scales, and which ones apply to
microscopic scales.
However, another, perhaps more broadly applicable way to conceive
of the emergent divide does involve a dose of complexity insofar as the
computational feasibility of going from the microscopic to the
macroscopic property tells the 'strength' of the emergence. This is
better understood given the following definition of (weak) emergence that comes from physics:
An emergent behavior of a physical system is a qualitative property
that can only occur in the limit that the number of microscopic
constituents tends to infinity."
Since there are no actually infinite systems in the real world, there
is no obvious naturally occurring notion of a hard separation between
the properties of the constituents of a system and those of the emergent
whole. As discussed below, classical mechanics is thought to be
emergent from quantum mechanics, though in principle, quantum dynamics
fully describes everything happening at a classical level. However, it
would take a computer larger than the size of the universe with more
computing time than life time of the universe to describe the motion of a
falling apple in terms of the locations of its electrons; thus we can take this to be a "strong" emergent divide.
In the case of strong emergence, the number of constituents can be much smaller. F.i. the emergent properties of a H2O molecule are very different from its constituent parts oxygen and hydrogen.
Some examples include:
- Classical mechanics
- The laws of classical mechanics can be said to emerge as a limiting case from the rules of quantum mechanics applied to large enough masses. This is particularly strange since quantum mechanics is generally thought of as more complicated than classical mechanics.
- Friction
- Forces between elementary particles are conservative. However,
friction emerges when considering more complex structures of matter,
whose surfaces can convert mechanical energy into heat energy when
rubbed against each other. Similar considerations apply to other
emergent concepts in continuum mechanics such as viscosity, elasticity, tensile strength, etc.
- Patterned ground
- the distinct, and often symmetrical geometric shapes formed by ground material in periglacial regions.
- Statistical mechanics
- initially derived using the concept of a large enough ensemble
that fluctuations about the most likely distribution can be all but
ignored. However, small clusters do not exhibit sharp first order phase transitions
such as melting, and at the boundary it is not possible to completely
categorize the cluster as a liquid or solid, since these concepts are
(without extra definitions) only applicable to macroscopic systems.
Describing a system using statistical mechanics methods is much simpler
than using a low-level atomistic approach.
- Electrical networks
- The bulk conductive response of binary (RC) electrical networks with random arrangements, known as the Universal Dielectric Response (UDR),
can be seen as emergent properties of such physical systems. Such
arrangements can be used as simple physical prototypes for deriving
mathematical formulae for the emergent responses of complex systems.
- Weather
- Temperature is sometimes used as an example of an emergent macroscopic behaviour. In classical dynamics, a snapshot
of the instantaneous momenta of a large number of particles at
equilibrium is sufficient to find the average kinetic energy per degree
of freedom which is proportional to the temperature. For a small number
of particles the instantaneous momenta at a given time are not
statistically sufficient to determine the temperature of the system.
However, using the ergodic hypothesis, the temperature can still be obtained to arbitrary precision by further averaging the momenta over a long enough time.
- Convection
- in a liquid or gas is another example of emergent macroscopic
behaviour that makes sense only when considering differentials of
temperature. Convection cells, particularly Bénard cells, are an example of a self-organizing system (more specifically, a dissipative system)
whose structure is determined both by the constraints of the system and
by random perturbations: the possible realizations of the shape and
size of the cells depends on the temperature gradient as well as the
nature of the fluid and shape of the container, but which configurations
are actually realized is due to random perturbations (thus these
systems exhibit a form of symmetry breaking).
In some theories of particle physics, even such basic structures as mass, space, and time are viewed as emergent phenomena, arising from more fundamental concepts such as the Higgs boson or strings. In some interpretations of quantum mechanics, the perception of a deterministic
reality, in which all objects have a definite position, momentum, and
so forth, is actually an emergent phenomenon, with the true state of
matter being described instead by a wavefunction which need not have a single position or momentum.
Most of the laws of physics
themselves as we experience them today appear to have emerged during
the course of time making emergence the most fundamental principle in
the universe and raising the question of what might be the most fundamental law of physics from which all others emerged. Chemistry can in turn be viewed as an emergent property of the laws of physics. Biology (including biological evolution) can be viewed as an emergent property of the laws of chemistry. Similarly, psychology could be understood as an emergent property of neurobiological laws. Finally, some economic theories understand economy as an emergent feature of psychology.
According to Laughlin,
for many particle systems, nothing can be calculated exactly from the
microscopic equations, and macroscopic systems are characterised by
broken symmetry: the symmetry present in the microscopic equations is
not present in the macroscopic system, due to phase transitions. As a
result, these macroscopic systems are described in their own
terminology, and have properties that do not depend on many microscopic
details. This does not mean that the microscopic interactions are
irrelevant, but simply that you do not see them anymore — you only see a
renormalized effect of them. Laughlin is a pragmatic theoretical
physicist: if you cannot, possibly ever, calculate the broken symmetry
macroscopic properties from the microscopic equations, then what is the
point of talking about reducibility?
Living, biological systems
Emergence and evolution
Life is a major source of complexity, and evolution
is the major process behind the varying forms of life. In this view,
evolution is the process describing the growth of complexity in the
natural world and in speaking of the emergence of complex living beings
and life-forms.
Life is thought to have emerged in the early RNA world when RNA chains began to express the basic conditions necessary for natural selection to operate as conceived by Darwin: heritability, variation of type, and competition for limited resources. Fitness
of an RNA replicator (its per capita rate of increase) would likely be a
function of adaptive capacities that were intrinsic (in the sense that
they were determined by the nucleotide sequence) and the availability of
resources.
The three primary adaptive capacities may have been (1) the capacity to
replicate with moderate fidelity (giving rise to both heritability and
variation of type); (2) the capacity to avoid decay; and (3) the
capacity to acquire and process resources. These capacities would have been determined initially by the folded configurations of the RNA replicators (see “Ribozyme”)
that, in turn, would be encoded in their individual nucleotide
sequences. Competitive success among different replicators would have
depended on the relative values of these adaptive capacities.
Regarding causality in evolution Peter Corning observes:
Synergistic effects of various kinds have played a major
causal role in the evolutionary process generally and in the evolution
of cooperation and complexity in particular... Natural selection is
often portrayed as a “mechanism”, or is personified as a causal
agency... In reality, the differential “selection” of a trait, or an
adaptation, is a consequence of the functional effects it produces in
relation to the survival and reproductive success of a given organism in
a given environment. It is these functional effects that are ultimately
responsible for the trans-generational continuities and changes in
nature.
Per his definition of emergence, Corning also addresses emergence and evolution:
[In] evolutionary processes, causation is iterative;
effects are also causes. And this is equally true of the synergistic
effects produced by emergent systems. In other words, emergence
itself... has been the underlying cause of the evolution of emergent
phenomena in biological evolution; it is the synergies produced by
organized systems that are the key
Swarming is a well-known behaviour in many animal species from marching locusts to schooling fish to flocking birds.
Emergent structures are a common strategy found in many animal groups:
colonies of ants, mounds built by termites, swarms of bees,
shoals/schools of fish, flocks of birds, and herds/packs of mammals.
An example to consider in detail is an ant colony.
The queen does not give direct orders and does not tell the ants what
to do. Instead, each ant reacts to stimuli in the form of chemical scent
from larvae, other ants, intruders, food and buildup of waste, and
leaves behind a chemical trail, which, in turn, provides a stimulus to
other ants. Here each ant is an autonomous unit that reacts depending
only on its local environment and the genetically encoded rules for its
variety of ant. Despite the lack of centralized decision making, ant
colonies exhibit complex behavior and have even demonstrated the ability
to solve geometric problems. For example, colonies routinely find the
maximum distance from all colony entrances to dispose of dead bodies.
It appears that environmental factors may play a role in
influencing emergence. Research suggests induced emergence of the bee
species Macrotera portalis.
In this species, the bees emerge in a pattern consistent with rainfall.
Specifically, the pattern of emergence is consistent with southwestern
deserts' late summer rains and lack of activity in the spring.
Organization of life
A broader example of emergent properties in biology is viewed in the biological organisation of life, ranging from the subatomic level to the entire biosphere. For example, individual atoms can be combined to form molecules such as polypeptide chains, which in turn fold and refold to form proteins,
which in turn create even more complex structures. These proteins,
assuming their functional status from their spatial conformation,
interact together and with other molecules to achieve higher biological
functions and eventually create an organism. Another example is how cascade phenotype reactions, as detailed in chaos theory, arise from individual genes mutating respective positioning. At the highest level, all the biological communities
in the world form the biosphere, where its human participants form
societies, and the complex interactions of meta-social systems such as
the stock market.
Emergence of mind
Among
the considered phenomena in the evolutionary account of life, as a
continuous history, marked by stages at which fundamentally new forms
have appeared - the origin of sapiens intelligence.
The emergence of mind and its evolution is researched and considered as
a separate phenomenon in a special system knowledge called noogenesis.
In humanity
Spontaneous order
Groups of human beings, left free to each regulate themselves, tend to produce spontaneous order, rather than the meaningless chaos often feared. This has been observed in society at least since Chuang Tzu
in ancient China. Human beings are the basic elements of social
systems, which perpetually interact and create, maintain, or untangle
mutual social bonds. Social bonds in social systems are perpetually
changing in the sense of the ongoing reconfiguration of their structure. A classic traffic roundabout
is also a good example, with cars moving in and out with such effective
organization that some modern cities have begun replacing stoplights at
problem intersections with roundabouts, and getting better results. Open-source software and Wiki projects form an even more compelling illustration.
Emergent processes or behaviors can be seen in many other places, such as cities, cabal and market-dominant minority phenomena in economics, organizational phenomena in computer simulations and cellular automata.
Whenever there is a multitude of individuals interacting, an order
emerges from disorder; a pattern, a decision, a structure, or a change
in direction occurs.
Economics
The stock market
(or any market for that matter) is an example of emergence on a grand
scale. As a whole it precisely regulates the relative security prices of
companies across the world, yet it has no leader; when no central planning
is in place, there is no one entity which controls the workings of the
entire market. Agents, or investors, have knowledge of only a limited
number of companies within their portfolio, and must follow the
regulatory rules of the market and analyse the transactions individually
or in large groupings. Trends and patterns emerge which are studied
intensively by technical analysts.
World Wide Web and the Internet
The World Wide Web
is a popular example of a decentralized system exhibiting emergent
properties. There is no central organization rationing the number of
links, yet the number of links pointing to each page follows a power law
in which a few pages are linked to many times and most pages are seldom
linked to. A related property of the network of links in the World Wide
Web is that almost any pair of pages can be connected to each other
through a relatively short chain of links. Although relatively well
known now, this property was initially unexpected in an unregulated
network. It is shared with many other types of networks called small-world networks.
Internet traffic can also exhibit some seemingly emergent properties. In the congestion control mechanism, TCP
flows can become globally synchronized at bottlenecks, simultaneously
increasing and then decreasing throughput in coordination. Congestion,
widely regarded as a nuisance, is possibly an emergent property of the
spreading of bottlenecks across a network in high traffic flows which
can be considered as a phase transition.
Another important example of emergence in web-based systems is social bookmarking
(also called collaborative tagging). In social bookmarking systems,
users assign tags to resources shared with other users, which gives rise
to a type of information organisation that emerges from this
crowdsourcing process. Recent research which analyzes empirically the
complex dynamics of such systems has shown that consensus on stable distributions and a simple form of shared vocabularies
does indeed emerge, even in the absence of a central controlled
vocabulary. Some believe that this could be because users who contribute
tags all use the same language, and they share similar semantic
structures underlying the choice of words. The convergence in social
tags may therefore be interpreted as the emergence of structures as
people who have similar semantic interpretation collaboratively index
online information, a process called semantic imitation.
Architecture and cities
Emergent structures appear at many different levels of organization or as spontaneous order. Emergent self-organization appears frequently in cities where no planning or zoning entity predetermines the layout of the city. The interdisciplinary study of emergent behaviors is not generally considered a homogeneous field, but divided across its application or problem domains.
Architects may not design all the pathways of a complex of
buildings. Instead they might let usage patterns emerge and then place
pavement where pathways have become worn, such as a desire path.
The on-course action and vehicle progression of the 2007 Urban Challenge could possibly be regarded as an example of cybernetic
emergence. Patterns of road use, indeterministic obstacle clearance
times, etc. will work together to form a complex emergent pattern that
can not be deterministically planned in advance.
The architectural school of Christopher Alexander
takes a deeper approach to emergence, attempting to rewrite the process
of urban growth itself in order to affect form, establishing a new
methodology of planning and design tied to traditional practices, an Emergent Urbanism. Urban emergence has also been linked to theories of urban complexity and urban evolution.
Building ecology is a conceptual framework for understanding
architecture and the built environment as the interface between the
dynamically interdependent elements of buildings, their occupants, and
the larger environment. Rather than viewing buildings as inanimate or
static objects, building ecologist Hal Levin views them as interfaces or
intersecting domains of living and non-living systems.
The microbial ecology of the indoor environment is strongly dependent
on the building materials, occupants, contents, environmental context
and the indoor and outdoor climate. The strong relationship between
atmospheric chemistry and indoor air quality and the chemical reactions
occurring indoors. The chemicals may be nutrients, neutral or biocides
for the microbial organisms. The microbes produce chemicals that affect
the building materials and occupant health and well-being. Humans
manipulate the ventilation, temperature and humidity to achieve comfort
with the concomitant effects on the microbes that populate and evolve.
Eric Bonabeau's attempt to define emergent phenomena is through
traffic: "traffic jams are actually very complicated and mysterious. On
an individual level, each driver is trying to get somewhere and is
following (or breaking) certain rules, some legal (the speed limit) and
others societal or personal (slow down to let another driver change into
your lane). But a traffic jam is a separate and distinct entity that
emerges from those individual behaviors. Gridlock
on a highway, for example, can travel backward for no apparent reason,
even as the cars are moving forward." He has also likened emergent
phenomena to the analysis of market trends and employee behavior.
Computer AI
Some artificially intelligent (AI) computer applications simulate emergent behavior for animation. One example is Boids, which mimics the swarming behavior of birds.
Language
It has been argued that the structure and regularity of language grammar, or at least language change, is an emergent phenomenon.
While each speaker merely tries to reach their own communicative goals,
they use language in a particular way. If enough speakers behave in
that way, language is changed.
In a wider sense, the norms of a language, i.e. the linguistic
conventions of its speech society, can be seen as a system emerging from
long-time participation in communicative problem-solving in various
social circumstances.
Emergent change processes
Within
the field of group facilitation and organization development, there
have been a number of new group processes that are designed to maximize
emergence and self-organization, by offering a minimal set of effective
initial conditions. Examples of these processes include
SEED-SCALE,
appreciative inquiry, Future Search, the world cafe or
knowledge cafe,
Open Space Technology, and others (Holman, 2010).