Ultraviolet astronomy is the observation of electromagnetic radiation at ultraviolet wavelengths between approximately 10 and 320 nanometres; shorter wavelengths—higher energy photons—are studied by X-ray astronomy and gamma ray astronomy. Ultraviolet light is not visible to the human eye.
Most of the light at these wavelengths is absorbed by the Earth's
atmosphere, so observations at these wavelengths must be performed from
the upper atmosphere or from space.
Overview
Ultraviolet line spectrum measurements (spectroscopy) are used to discern the chemical composition, densities, and temperatures of the interstellar medium, and the temperature and composition of hot young stars. UV observations can also provide essential information about the evolution of galaxies. They can be used to discern the presence of a hot white dwarf or main sequence companion in orbit around a cooler star.
The ultraviolet universe looks quite different from the familiar stars and galaxies seen in visible light.
Most stars are actually relatively cool objects emitting much of their electromagnetic radiation in the visible or near-infrared
part of the spectrum. Ultraviolet radiation is the signature of hotter
objects, typically in the early and late stages of their evolution.
In the Earth's sky seen in ultraviolet light, most stars would fade in
prominence. Some very young massive stars and some very old stars and
galaxies, growing hotter and producing higher-energy radiation near
their birth or death, would be visible. Clouds of gas and dust would
block the vision in many directions along the Milky Way.
Space-based solar observatories such as SDO and SOHO use ultraviolet telescopes (called AIA and EIT, respectively) to view activity on the Sun and its corona. Weather satellites such as the GOES-R series also carry telescopes for observing the Sun in ultraviolet.
In his middle and late career, Gamow directed much of his attention to teaching and wrote popular books on science, including One Two Three... Infinity and the Mr Tompkins series of books (1939–1967). Some of his books are still in print more than a half-century after their original publication.
Early life and career
Gamow was born in Odessa, Russian Empire.
His father taught Russian language and literature in high school, and
his mother taught geography and history at a school for girls. In
addition to Russian, Gamow learned to speak some French from his mother
and German from a tutor. Gamow learned English in his college years and
became fluent. Most of his early publications were in German or Russian,
but he later used English for both technical papers and for the lay
audience.
He was educated at the Institute of Physics and Mathematics in Odessa (1922–23) and at the University of Leningrad (1923–1929). Gamow studied under Alexander Friedmann in Leningrad,
until Friedmann's early death in 1925, which required him to change
dissertation advisors. At the university, Gamow made friends with three
other students of theoretical physics, Lev Landau, Dmitri Ivanenko, and Matvey Bronshtein. The four formed a group they called the Three Musketeers,
which met to discuss and analyze the ground-breaking papers on quantum
mechanics published during those years. He later used the same phrase to
describe the Alpher, Herman, and Gamow group.
In 1931, Gamow was elected a corresponding member of the Academy of Sciences of the USSR at age 28 – one of the youngest in its history. During the period 1931–1933, Gamow worked in the Physical Department of the Radium Institute (Leningrad) headed by Vitaly Khlopin [ru]. Europe's first cyclotron was designed under the guidance and direct participation of Igor Kurchatov,
Lev Mysovskii and Gamow. In 1932, Gamow and Mysovskii submitted a draft
design for consideration by the Academic Council of the Radium
Institute, which approved it. The cyclotron was not completed until
1937.
Bragg Laboratory staff in 1931: W. H. Bragg (sitting, center): physicist A. Lebedev (leftmost), G. Gamow (rightmost)
Radioactive decay
In
the early 20th century, radioactive materials were known to have
characteristic exponential decay rates, or half-lives. At the same time,
radiation emissions were known to have certain characteristic energies.
By 1928, Gamow in Göttingen had solved the theory of the alpha decay of a nucleus via tunnelling, with mathematical help from Nikolai Kochin. The problem was also solved independently by Ronald W. Gurney and Edward U. Condon.Gurney and Condon did not, however, achieve the quantitative results achieved by Gamow.
Classically, the particle is confined to the nucleus because of the high energy requirement to escape the very strong nuclear potential well.
Also classically, it takes an enormous amount of energy to pull apart
the nucleus, an event that would not occur spontaneously. In quantum mechanics,
however, there is a probability the particle can "tunnel through" the
wall of the potential well and escape. Gamow solved a model potential
for the nucleus and derived from first principles a relationship between
the half-life
of the alpha-decay event process and the energy of the emission, which
had been previously discovered empirically and was known as the Geiger–Nuttall law. Some years later, the name Gamow factor or Gamow–Sommerfeld factor was applied to the probability of incoming nuclear particles tunnelling through the electrostatic Coulomb barrier and undergoing nuclear reactions.
Defection
Gamow
worked at a number of Soviet establishments before deciding to flee the
Soviet Union because of increased oppression. In 1931, he was
officially denied permission to attend a scientific conference in Italy.
Also in 1931, he married Lyubov Vokhmintseva (Russian: Любовь Вохминцева), another physicist in Soviet Union, whom he nicknamed "Rho" after the Greek letter.
Gamow and his new wife spent much of the next two years trying to leave
the Soviet Union, with or without official permission. Niels Bohr and other friends invited Gamow to visit during this period, but Gamow could not get permission to leave.
Gamow later said that his first two attempts to defect with his wife were in 1932 and involved trying to kayak: first a planned 250-kilometer paddle over the Black Sea to Turkey, and another attempt from Murmansk to Norway. Poor weather foiled both attempts, but they had not been noticed by the authorities.
In 1933, Gamow was suddenly granted permission to attend the 7th Solvay Conference on physics, in Brussels.
He insisted on having his wife accompany him, even saying that he would
not go alone. Eventually the Soviet authorities relented and issued
passports for the couple. The two attended and arranged to extend their
stay, with the help of Marie Curie and other physicists. Over the next year, Gamow obtained temporary work at the Curie Institute, University of London, and the University of Michigan.
In 1935, Gamow's son, Igor Gamow was born (in a 1947 book, Gamow's dedication was "To my son IGOR, Who Would Rather Be a Cowboy"). George Gamow became a naturalized American in 1940. He retained his formal association with GWU until 1956.
During World War II, Gamow did not work directly on the Manhattan Project producing the atomic bomb, in spite of his knowledge of radioactivity and nuclear fusion. He continued to teach physics at GWU and consulted for the US Navy.
Gamow was interested in the processes of stellar evolution and the early history of the Solar System. In 1945, he co-authored a paper supporting work by German theoretical physicist Carl Friedrich von Weizsäcker on planetary formation in the early Solar System. Gamow published another paper in the British journal Nature
in 1948, in which he developed equations for the mass and radius of a
primordial galaxy (which typically contains about one hundred billion
stars, each with a mass comparable with that of the Sun).
Big Bang nucleosynthesis
Gamow's work led the development of the hot "big bang" theory of the expanding universe. He was the earliest to employ Alexander Friedmann's and Georges Lemaître's
non-static solutions of Einstein's gravitational equations describing a
universe of uniform matter density and constant spatial curvature.
Gamow's crucial advance would provide a physical reification of
Lemaître's idea of a unique primordial quantum. Gamow did this by
assuming that the early universe was dominated by radiation rather than
by matter.
Most of the later work in cosmology is founded in Gamow's theory. He
applied his model to the question of the creation of the chemical
elements and to the subsequent condensation of matter into galaxies, whose mass and diameter he was able to calculate in terms of the fundamental physical parameters, such as the speed of light c, Newton's gravitational constant G, Sommerfeld's fine-structure constant α, and Planck's constant h.
Gamow's interest in cosmology arose from his earlier interest in
energy generation and element production and transformation in stars. This work, in turn, evolved from his fundamental discovery of quantum tunneling as the mechanism of nuclear alpha decay, and his application of this theory to the inverse process to calculate rates of thermonuclear reaction.
At first, Gamow believed that all the elements might be produced
in the very high temperature and density early stage of the universe.
Later, he revised this opinion on the strength of compelling evidence
advanced by Fred Hoyle and others, that elements heavier than lithium are largely produced in thermonuclear reactions in stars
and in supernovae. Gamow formulated a set of coupled differential
equations describing his proposed process and assigned, as a PhD
dissertation topic, his graduate student Ralph Alpher the task of solving the equations numerically. These results of Gamow and Alpher appeared in 1948 as the Alpher–Bethe–Gamow paper.
Before his interest turned to the question of the genetic code, Gamow
published about twenty papers on cosmology. The earliest was in 1939
with Edward Teller on galaxy formation,
followed in 1946 by the first description of cosmic nucleosynthesis. He
also wrote many popular articles as well as academic textbooks on this
and other subjects.
In 1948, he published a paper dealing with an attenuated version
of the coupled set of equations describing the production of the proton
and the deuteron from thermal neutrons. By means of a simplification and
using the observed ratio of hydrogen to heavier elements, he was able
to obtain the density of matter at the onset of nucleosynthesis and from
this the mass and diameter of the early galaxies.
In 1953 he produced similar results, but this time based on another
determination of the density of matter and radiation, at the time at
which they became equal.
In this paper, Gamow determined the density of the relict background
radiation, from which a present temperature of 7 K was predicted – a
value which was slightly more than twice the presently-accepted value.
In 1967, he published reminiscences and recapitulation of his own
work as well as the work of Alpher and Robert Herman (both with Gamow
and also independently of him). This was prompted by the discovery of the cosmic background radiation
by Penzias and Wilson in 1965; Gamow, Alpher, and Herman felt that they
did not receive the credit they deserved for their theoretical
predictions of its existence and source. Gamow was disconcerted by the fact that the authors of a communication[27]
explaining the significance of the Penzias/Wilson observations failed
to recognize and cite the previous work of Gamow and his collaborators.
DNA and RNA
In 1953, Francis Crick, James Watson, Maurice Wilkins and Rosalind Franklin discovered the double helix structure of the DNA macromolecule. Gamow attempted to solve the problem of how the ordering of four different bases (adenine, cytosine, thymine and guanine) in DNA chains might control the synthesis of proteins from their constituent amino acids. Crick has said that Gamow's suggestions helped him in his own thinking about the problem. As related by Crick, Gamow observed that the 43 = 64 possible permutations of the four DNA bases, taken three at a time, would be reduced to 20 distinct combinations if the order was irrelevant.
Gamow proposed that these 20 combinations might code for the twenty
amino acids which, he suggested, might well be the sole constituents of
all proteins. Gamow's contribution to solving the problem of genetic
coding gave rise to important models of biological degeneracy.
The specific system
that Gamow was proposing (called "Gamow's diamonds") proved to be
incorrect. The triplets were supposed to be overlapping, so that in the
sequence GGAC (for example), GGA could produce one amino acid and GAC
another, and also non-degenerate
(meaning that each amino acid would correspond to one combination of
three bases – in any order). Later protein sequencing work proved that
this could not be the case; the true genetic code is non-overlapping and degenerate, and changing the order of a combination of bases does change the amino acid.
In 1954, Gamow and Watson co-founded the RNA Tie Club.
This was a discussion group of leading scientists concerned with the
problem of the genetic code, which counted among its members the
physicists Edward Teller and Richard Feynman.
In his autobiographical writings, Watson later acknowledged the great
importance of Gamow's insightful initiative. However, this did not
prevent him from describing this colorful personality as a "zany",
card-trick playing, limerick-singing, booze-swilling, practical–joking
"giant imp".
Late career and life
Gamow's grave in Green Mountain Cemetery, Boulder, Colorado, US
Gamow worked at George Washington University from 1934 until 1954, when he became a visiting professor at the University of California, Berkeley. In 1956, he moved to the University of Colorado Boulder, where he remained for the rest of his career. In 1956, Gamow became one of the founding members of the Physical Science Study Committee (PSSC), which later reformed teaching of high-school physics in the post-Sputnik years. Also in 1956, he divorced his first wife. Gamow later married Barbara Perkins (an editor for one of his publishers) in 1958.
In 1959, Gamow, Hans Bethe, and Victor Weisskopf publicly supported the re-entry of Frank Oppenheimer into teaching college physics at the University of Colorado, as the Red Scare began to fade (J. Robert Oppenheimer was the older brother of Frank Oppenheimer, and both of them had worked on the Manhattan Project before their careers in physics were derailed by McCarthyism).
While in Colorado, Frank Oppenheimer became increasingly interested in
teaching science through simple hands-on experiments, and he eventually
moved to San Francisco to found the Exploratorium. Gamow would not live to see his colleague's opening of this innovative new science museum, in late August 1969.
In his 1961 book The Atom and its Nucleus, Gamow proposed representing the periodic system of the chemical elements as a continuous tape, with the elements in order of atomic number
wound round in a three-dimensional helix whose diameter increased
stepwise (corresponding to the longer rows of the conventional periodic
table).
Gamow continued his teaching at the University of Colorado
Boulder and focused increasingly on writing textbooks and books on
science for the general public. After several months of ill health,
surgeries on his circulatory system, diabetes, and liver problems, Gamow
was dying from liver failure, which he had called the "weak link" that could not withstand the other stresses.
In a letter written to Ralph Alpher on August 18, he had written,
"The pain in the abdomen is unbearable and does not stop". Prior to
this, there had been a long exchange of letters with his former student,
in which he was seeking a fresh understanding of some concepts used in
his earlier work, with Paul Dirac. Gamow relied on Alpher for deeper
understanding of mathematics.
On August 19, 1968, Gamow died at age 64 in Boulder, Colorado,
and was buried there in Green Mountain Cemetery. The physics department
tower at the University of Colorado at Boulder is named after him.
Gamow was a well-known prankster, who delighted in practical
jokes and humorous twists embedded in serious scientific publications. His most famous prank was the pioneering Alpher–Bethe–Gamow paper, which was serious in its style and content. However, Gamow could not resist adding his colleague Hans Bethe to the list of authors, as a pun on the first three letters of the Greek alphabet.
Gamow was an atheist.
Writings
Gamow
was a highly successful science writer, with several of his books still
in print more than a half-century after their initial publication. As
an educator, Gamow recognized and emphasized fundamental principles that
were unlikely to become obsolete, even as the pace of science and
technology accelerated. He also conveyed a sense of excitement with the
revolution in physics and other scientific topics of interest to the
common reader. Gamow himself sketched the many illustrations for his
books, which added a new dimension to and complemented what he intended
to convey in the text. He was unafraid to introduce mathematics wherever
it was essential, but he tried to avoid deterring potential readers by
including large numbers of equations that did not illustrate essential
points.
Before his death, Gamow was working with Richard Blade on a textbook Basic Theories in Modern Physics, but the work was never completed or published under that title. Gamow was also writing My World Line: An Informal Autobiography, which was published posthumously in 1970.
A collection of Gamow's writings was donated to The George Washington University
in 1996. The materials include correspondence, articles, manuscripts
and printed materials both by and about George Gamow. The collection is
currently under the care of GWU's Special Collections Research Center,
located in the Estelle and Melvin Gelman Library.
Social neuroscience is an interdisciplinary field devoted to understanding the relationship between social experiences and biological systems. Humans are fundamentally a social species, rather than solitary. As such, Homo sapiens create emergent organizations
beyond the individual—structures that range from dyads, families, and
groups to cities, civilizations, and cultures. In this regard, studies
indicate that various social influences including life events, poverty,
unemployment and loneliness can influence health related biomarkers.
The term "social neuroscience" can be traced to a publication entitled
"Social Neuroscience Bulletin" that was published quarterly between 1988
and 1994. The term was subsequently popularized in an article by John Cacioppo and Gary Berntson, published in the American Psychologist in 1992. Cacioppo and Berntson are considered as the legitimate fathers of social neuroscience. Still a young field, social neuroscience is closely related to affective neuroscience and cognitive neuroscience, focusing on how the brain mediates social interactions. The biological underpinnings of social cognition are investigated in social cognitive neuroscience.
Overview
Traditional neuroscience has for many years considered the nervous system
as an isolated entity and largely ignored influences of the social
environments in which humans and many animal species live. In fact, we
now recognize the considerable impact of social structures on the
operations of the brain and body. These social factors operate on the
individual through a continuous interplay of neural, neuroendocrine, metabolic and immune factors on brain and body, in which the brain is the central regulatory organ and also a malleable target of these factors. Social neuroscience investigates the biological mechanisms that underlie social processes and behavior, widely considered one of the major problem areas for the neurosciences in the 21st century, and applies concepts and methods of biology to develop theories of social processes and behavior in the social and behavioral sciences.
Social neuroscience capitalizes on biological concepts and methods to
inform and refine theories of social behavior, and it uses social and
behavioral constructs and data to advance theories of neural
organization and function.
Throughout most of the 20th century, social and biological
explanations were widely viewed as incompatible. But advances in recent
years have led to the development of a new approach synthesized from the
social and biological sciences. The new field of social neuroscience
emphasizes the complementary relationship between the different levels
of organization, spanning the social and biological domains (e.g., molecular, cellular, system,
person, relational, collective, societal) and the use of multi-level
analyses to foster understanding of the mechanisms underlying the human
mind and behavior.
Methods
A number of methods are used in social neuroscience to investigate the confluence of neural and social processes. These methods draw from behavioral techniques developed in social psychology, cognitive psychology, and neuropsychology, and are associated with a variety of neurobiological techniques including functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), positron emission tomography (PET), facial electromyography (EMG), transcranial magnetic stimulation (TMS), electroencephalography (EEG), event-related potentials (ERPs), electrocardiograms, electromyograms, endocrinology, immunology, galvanic skin response (GSR), single-cell recording, and studies of focal brain lesion patients. In recent years, these methods have been complemented by virtual reality techniques (VR) and hormonal
measures. Animal models are also important to investigate the putative
role of specific brain structures, circuits, or processes (e.g., the reward system and drug addiction).
In addition, quantitative meta-analyses are important to move beyond
idiosyncrasies of individual studies, and neurodevelopmental
investigations can contribute to our understanding of brain-behavior
associations.
The two most popular forms of methods used in social neuroscience are
fMRI and EEG. fMRI are very cost efficient and high in spatial
resolution. However, they are low in temporal resolution and therefore,
are best to discover pathways in the brain that are used during social
experiments. fMRI have low temporal resolution (timing) because they
read oxygenated blood levels that pool to the parts of the brain that
are activated and need more oxygen. Thus, the blood takes time to travel
to the part of the brain being activated and in reverse provides a
lower ability to test for exact timing of activation during social
experiments. EEG is best used when a researcher is trying to brain map a
certain area that correlates to a social construct
that is being studied. EEGs provide high temporal resolution but low
spatial resolution. In which, the timing of the activation is very
accurate but it is hard to pinpoint exact areas on the brain,
researchers are to narrow down locations and areas but they also create a
lot of "noise". Most recently, researchers have been using TMS which is
the best way to discover the exact location in the process of brain
mapping. This machine can turn on and off parts of the brain which then
allows researchers to test what that part of the brain is used for
during social events. However, this machine is so expensive that it is
rarely used.
Note: Most of these methods can only provide correlations between
brain mapping and social events (apart from TMS), a con of Social
Neuroscience is that the research must be interpreted through
correlations which can cause a decreased content validity. For example,
during an experiment when a participant is doing a task to test for a
social theory and a part of the brain is activated, it is impossible to
form causality because anything else in the room or the thoughts of the
person could have triggered that response. It is very hard to isolate
these variables during these experiments. That is why self-reports are
very important. This will also help decrease the chances of VooDoo
correlations (correlations that are too high and over 0.8 which look
like a correlation exists between two factors but actually is just an
error in design and statistical measures). Another way to avoid this
con, is to use tests with hormones that can infer causality. For
example, when people are given oxytocin and placebos and we can test
their differences in social behavior between other people. Using SCRs
will also help isolate unconscious thoughts and conscious thoughts
because it is the body's natural parasympathetic response to the outside
world. All of these tests and devices will help social neuroscientists
discover the connections in the brain that are used to carry out our
everyday social activities.
Primarily psychological methods include performance-based measures that record response time and/or accuracy, such as the Implicit Association Test;
observational measures such as preferential looking in infant studies;
and, self-report measures, such as questionnaire and interviews.
Neurobiological methods can be grouped together into ones that
measure more external bodily responses, electrophysiological methods,
hemodynamic measures, and lesion methods.
Bodily response methods include GSR (also known as skin conductance
response (SCR)), facial EMG, and the eyeblink startle response.
Electrophysiological methods include single-cell recordings, EEG, and
ERPs. Hemodynamic measures, which, instead of directly measuring neural
activity, measure changes in blood flow, include PET and fMRI. Lesion
methods traditionally study brains that have been damaged via natural
causes, such as strokes, traumatic injuries, tumors, neurosurgery,
infection, or neurodegenerative disorders. In its ability to create a
type of 'virtual lesion' that is temporary, TMS may also be included in
this category. More specifically, TMS methods involve stimulating one
area of the brain to isolate it from the rest of the brain, imitating a
brain lesion. This is particularly helpful in brain mapping, a key
approach in social neuroscience designed to determine which areas of the
brain are activated during certain activities.
Society for Social Neuroscience
A dinner to discuss the challenges and opportunities in the interdisciplinary field of social neuroscience at the Society for Neuroscience meeting (Chicago, November 2009) resulted in a series of meetings led by John Cacioppo and Jean Decety with social neuroscientists, psychologists, neuroscientists, psychiatrists and neurologists in Argentina, Australia, Chile, China, Colombia, Hong Kong, Israel, Japan, the Netherlands, New Zealand, Singapore, South Korea, Taiwan, the United Kingdom and the United States.
Social neuroscience was defined broadly as the interdisciplinary study
of the neural, hormonal, cellular, and genetic mechanisms underlying the
emergent structures that define social species. Thus, among the
participants in these meetings were scientists who used a wide variety
of methods in studies of animals as well as humans, and patients as well
as normal participants. The consensus also emerged that a Society for
Social Neuroscience should be established to give scientists from
diverse disciplines and perspectives the opportunity to meet,
communicate with, and benefit from the work of each other. The
international, interdisciplinary Society for social neuroscience (http://S4SN.org) was launched at the conclusion of these consultations in Auckland,
New Zealand on 20 January 2010, and the inaugural meeting for the
Society was held on November 12, 2010, the day prior to the 2010 Society
for Neuroscience meeting (San Diego, CA).
The evolutionary argument against naturalism (EAAN) is a philosophical argument asserting a problem with believing both evolution and philosophical naturalism simultaneously. The argument was first proposed by Alvin Plantinga in 1993 and "raises issues of interest to epistemologists, philosophers of mind, evolutionary biologists, and philosophers of religion". The EAAN argues that the combined belief in both evolutionary theory and naturalism is epistemically self-defeating.
The argument for this is that if both evolution and naturalism are
true, then the probability of having reliable cognitive faculties is
low. This argument comes as an expansion of the argument from reason, although the two are separate philosophical arguments.
Development of the idea
The idea that "naturalism" undercuts its own justification was put forward by Arthur Balfour. C. S. Lewis popularised it in the first edition of his book Miracles in 1947. Similar arguments were advanced by Richard Taylor in Metaphysics, as well as by Stephen Clark, Richard Purtill and J. P. Moreland. In 2003 Victor Reppert developed a similar argument in detail in his book C.S. Lewis's Dangerous Idea, In Defense of the Argument from Reason. Contemporary philosophers who have employed a similar argument against physical determinism are James Jordan and William Hasker.
Plantinga proposed his "evolutionary argument against naturalism" in 1993. In the twelfth chapter of his book Warrant and Proper Function, Plantinga developed Lewis' idea, and constructed two formal arguments against evolutionary naturalism. He further developed the idea in an unpublished manuscript entitled "Naturalism Defeated" and in his 2000 book Warranted Christian Belief, and expanded the idea in Naturalism Defeated?, a 2002 anthology edited by James Beilby. He also responded to several objections to the argument in his essay "Reply to Beilby's Cohorts" in Beilby's anthology.
In the 2008 publication Knowledge of God Plantinga presented a formulation of the argument that solely focused on semantic epiphenomenalism instead of the former four jointly exhaustive categories.
Plantinga repeats the argument in his 2011 book Where the Conflict Really Lies: Science, Religion, and Naturalism.
Plantinga's 1993 formulation of the argument
Plantinga
argues that combining naturalism and evolution is self-defeating,
because, under these assumptions, the probability that humans have
reliable cognitive faculties is low or inscrutable. He claimed that several thinkers, including C. S. Lewis,
had seen that evolutionary naturalism seemed to lead to a deep and
pervasive skepticism and to the conclusion that our unreliable cognitive
or belief-producing faculties cannot be trusted to produce more true
beliefs than false beliefs. He claimed that "Darwin himself had worries along these lines" and quoted from an 1881 letter:
But then with me the horrid doubt
always arises whether the convictions of man's mind, which has been
developed from the mind of the lower animals, are of any value or at all
trustworthy. Would any one trust in the convictions of a monkey's mind,
if there are any convictions in such a mind?
— Charles Darwin, to William Graham 3 July 1881
In the letter, Darwin had expressed agreement with William Graham's
claim that natural laws implied purpose and the belief that the universe
was "not the result of chance", but again showed his doubts about such
beliefs and left the matter as insoluble.
Darwin only had this doubt about questions beyond the scope of science,
and thought science was well within the scope of an evolved mind. Michael Ruse
said that by presenting it as "Darwin's doubt" that evolutionary
naturalism is self-defeating, Plantinga failed to note that Darwin at
once excused himself from philosophical matters he did not feel
competent to consider. Others, such as Evan Fales, agreed that this citation allowed Plantinga to call the source of the problem EAAN addresses Darwin's Doubt.
Also, contrary to Ruse's claim, Plantinga gave the name "Darwin's
Doubt" not to the idea that the conjunction of naturalism and evolution
is self-defeating, but rather to the view that given naturalism and
evolution our cognitive faculties are unlikely to be reliable.
Plantinga asserts that "this doubt arises for naturalists or atheists,
but not for those who believe in God. That is because if God has created
us in his image, then even if he fashioned us by some evolutionary
means, he would presumably want us to resemble him in being able to
know; but then most of what we believe might be true even if our minds
have developed from those of the lower animals."
Plantinga defined:
N as naturalism, which he defined as "the idea that there
is no such person as God or anything like God; we might think of it as
high-octane atheism or perhaps atheism-plus."
E as the belief that human beings have evolved in conformity with current evolutionary theory
R as the proposition that our faculties are "reliable",
where, roughly, a cognitive faculty is "reliable" if the great bulk of
its deliverances are true. He specifically cited the example of a
thermometer stuck at 72 °F (22 °C) placed in an environment which
happened to be at 72 °F as an example of something that is not
"reliable" in this sense
and suggested that the conditional probability of R given N and E, or P(R|N&E), is low or inscrutable.
Plantinga's argument began with the observation that our beliefs
can only have evolutionary consequences if they affect behaviour. To put
this another way, natural selection does not directly select for true
beliefs, but rather for advantageous behaviours. Plantinga distinguished
the various theories of mind-body interaction into four jointly
exhaustive categories:
Epiphenomenalism, where behaviour is not caused by beliefs. "if this way of thinking is right, beliefs would be invisible to evolution" so P(R|N&E) would be low or inscrutable.
Semantic epiphenomenalism, where beliefs have a causative link to behaviour but not by virtue of their semantic content. Under this theory, a belief would be some form of long-term neuronal event.
However, on this view P(R|N&E) would be low because the semantic
content of beliefs would be invisible to natural selection, and it is
semantic content that determines truth-value.
Beliefs are causally efficacious with respect to behaviour, but maladaptive, in which case P(R|N&E) would be low, as R would be selected against.
Beliefs are causally efficacious with respect to behaviour and also
adaptive, but they may still be false. Since behaviour is caused by both
belief and desire, and desire can lead to false belief, natural
selection would have no reason for selecting true but non-adaptive
beliefs over false but adaptive beliefs. Thus P(R|N&E) in this case
would also be low.
Plantinga pointed out that innumerable belief-desire pairs could
account for a given behaviour; for example, that of a prehistoric
hominid fleeing a tiger:
Perhaps Paul very much likes the idea of being
eaten, but when he sees a tiger, always runs off looking for a better
prospect, because he thinks it unlikely the tiger he sees will eat him.
This will get his body parts in the right place so far as survival is
concerned, without involving much by way of true belief. ... Or perhaps
he thinks the tiger is a large, friendly, cuddly pussycat and wants to
pet it; but he also believes that the best way to pet it is to run away
from it. ... Clearly there are any number of belief-cum-desire systems
that equally fit a given bit of behaviour.
Thus, Plantinga argued, the probability that our minds are reliable under a conjunction of philosophical naturalism and naturalistic evolution
is low or inscrutable. Therefore, to assert that naturalistic evolution
is true also asserts that one has a low or unknown probability of being
right. This, Plantinga argued, epistemically defeats
the belief that naturalistic evolution is true and that ascribing truth
to naturalism and evolution is internally dubious or inconsistent.
Responses
Fitelson and Sober's response
In a 1998 paper Branden Fitelson of the University of California, Berkeley and Elliott Sober of the University of Wisconsin–Madison
set out to show that the arguments presented by Plantinga contain
serious errors. Plantinga construed evolutionary naturalism as the
conjunction of the idea that human cognitive faculties arose through
evolutionary mechanisms, and naturalism which he equated to atheism.
Plantinga tried to throw doubt on this conjunction with a preliminary
argument that the conjunction is probably false, and a main argument
that it is self-defeating; if you believe it you should stop believing
it.
First, they criticised Plantinga's use of a Bayesian framework in which he arbitrarily assigned initial probabilities without empirical evidence,
predetermining the outcome in favor of traditional theism, and
described this as a recipe for replacing any non-deterministic theory in
the natural sciences, so that for example a probable outcome predicted
by quantum mechanics
would be seen as the outcome of God's will. Plantinga's use of R to
mean that "the great bulk" of our beliefs are true fails to deal with
the cumulative effect of adding beliefs which have variable reliability
about different subjects. Plantinga asserted that the traditional theist
believes being made in God's image includes a reflection of divine
powers as a knower, but cognitive science
finds human reasoning subject to biases and systematic error.
Traditional theology is not shown to predict this varying reliability as
well as science, and there is the theological problem
of the omnipotent Creator producing such imperfection. They described
how Plantinga set out various scenarios of belief affecting evolutionary
success, but undercut the low probability he previously required when
he suggested an "inscrutable" probability, and by ignoring availability
of variants he fails to show that false beliefs will be equally adaptive
as his claim of low probability assumes. Even if his claims of
improbability were correct, that need not affect belief in evolution,
and they considered it would be more sensible to accept that
evolutionary processes sometimes have improbable outcomes.
They assessed Plantinga's main argument—which asserts that since
the reliability of evolutionary naturalism is low or of inscrutable
value, those believing it should withhold assent from its reliability,
and thus withhold assent from anything else they believe including
evolutionary naturalism, which is therefore self-defeating—and found it
unconvincing, having already disputed his argument that the reliability
is low. Even if E&N defeated the claim that 'at least 90% of
our beliefs are true,' they considered that Plantinga must show that it
also defeats the more modest claim that 'at least a non-negligible
minority of our beliefs are true'. They considered his sentiment that
high probability is required for rational belief to be repudiated by
philosophical lessons such as the lottery paradox,
and that each step in his argument requires principles different from
those he had described. They concluded that Plantinga has drawn
attention to unreliability of cognitive processes that is already taken
into account by evolutionary scientists who accept that science is a
fallible exercise, and appreciate the need to be as scrupulous as
possible with the fallible cognitive processes available. His hyperbolic doubt
as a defeater for evolutionary naturalism is equally a defeater for
theists who rely on their belief that their mind was designed by a
non-deceiving God, and neither "can construct a non-question-begging
argument that refutes global skepticism."
In 2020 a philosophy paper was published called Does the
Evolutionary Argument Against Naturalism Defeat God's Beliefs Which
argued that if the EAAN provides the naturalist with a defeater for all
of her beliefs, then an extension of it appears to provide God with a
defeater for all of his beliefs.
Robbins' response
Indiana University South Bend Professor of Philosophy J. Wesley Robbins contended that Plantinga's argument applied only to Cartesian philosophies of mind
but not to pragmatist philosophies of mind. Robbins' argument, stated
roughly, was that while in a Cartesian mind beliefs can be identified
with no reference to the environmental factors that caused them, in a
pragmatic mind they are identifiable only with reference to those
factors. That is to say, in a pragmatic mind beliefs would not even
exist if their holder had not come in contact with external
belief-producing phenomena in the first place.
Naturalism Defeated?
A collection of essays entitled Naturalism Defeated? (2002) contains responses by 11 philosophers to EAAN.
According to James K. Beilby, editor of the volume, Plantinga's
proposition "raises issues of interest to epistemologists, philosophers
of mind, evolutionary biologists, and philosophers of religion". The responsive essays include the following:
William Ramsey argued that Plantinga "overlooks the most
sensible way . . . to get clear on how truth can be a property of
beliefs that bestows an advantage on cognitive systems". He also argued
that some of our cognitive faculties are slightly unreliable, and E&N seems better suited than theism to explain this imperfection.
Jerry Fodor
argued that there is a plausible historical scenario according to which
our minds were selected because their cognitive mechanisms produced, by
and large, adaptive true beliefs.
Evan Fales
argued that Plantinga had not demonstrated that the reliability of our
cognitive faculties is improbable, given Neo-Darwinism, and emphasizes
that "if Plantinga's argument fails here, then he will not have shown
that [N&E] is probabilistically incoherent." Also, given how
expensive (in biological terms) our brain is, and considering we are
rather unremarkable creatures apart from our brains, it would be quite
improbable that our rational faculties be selected if unreliable. "Most
of our eggs are in that basket," said Fales. Fales argued along the same
as Robbins: take a mental representation,
of heat, for example. Only so long as it is really caused by heat can
we call it a mental representation of heat; otherwise, it is not at all a
mental representation, of heat or of anything else: "so long as
representations [semantics] are causally linked to the world via the
syntactic structures in the brain to which they correspond [syntax],
this will guarantee that syntax maps onto semantics in a generally
truth-preserving way."
This is a direct response to one of Plantinga's scenarios where,
according to Plantinga, false-belief generating mechanisms may have been
naturally selected.
Michael Bergmann suggested that Thomas Reid offered the resources for a commonsense (Reidian) defense of naturalism against EAAN.
Ernest Sosa drew on features of Descartes'
epistemology to argue that while "[i]ssues of circularity do arise as
to how we can rationally and knowledgeably adopt [an epistemically
propitious] view about our own epistemic powers," nonetheless, "these
problems are not exclusive to naturalism."
James Van Cleve suggested that even if the probability thesis is
true, it need not deliver an undefeated defeater to R, and that even if
one has a defeater for R, it doesn't follow that one has a defeater for
everything.
Richard Otte thought that the argument "ignore[d] other information we have that would make R likely."
William Talbott suggested that "Plantinga has misunderstood the role of undercutting defeaters in reasoning."
Trenton Merricks said that "in general, inferences from low or inscrutable conditional probability to defeat are unjustified."
William Alston
argued that the claim that P(R/N&E) is low is poorly supported; if,
instead, it is inscrutable, this has no clear relevance to the claim
that (1) is a defeater for N&E.
Naturalism Defeated? also included Plantinga's replies to both
the critical responses contained in the book and to some objections
raised by others, including Fitelson & Sober:
Plantinga expounded the notion of Rationality Defeaters
in terms of his theory of warrant and proper function and distinguishes
between Humean Defeaters and Purely Alethic Defeaters, suggesting that
although a naturalist will continue to assume R "but (if he reflects on
the matter) he will also think, sadly enough, that what he can't help
believing is unlikely to be true."
Plantinga argued that semantic epiphenomenalism is very likely on N&E because, if materialism is true, beliefs would have to be neurophysiological events whose propositional content cannot plausibly enter the causal chain. He also suggests that the reliability
of a cognitive process requires the truth of a substantial proportion
of the beliefs it produces, and that a process which delivered beliefs
whose probability of truth was in the neighbourhood of 0.5 would have a
vanishingly unlikely chance of producing (say) 1000 beliefs 75% of which
were true.
In The conditionalisation problem, Plantinga discussed the possibility that N+
i.e. "Naturalism plus R," could be a basic belief thus staving off
defeat of R, suggesting that this procedure cannot be right in general
otherwise every defeater could automatically be defeated, introducing
the term "defeater-deflector " and initially exploring the conditions under which a defeater-deflector can be valid.
Plantinga concluded that the objections pose a challenge to EAAN,
but that there are successful arguments against the objections.
Ruse's response
In a chapter titled 'The New Creationism: Its Philosophical Dimension', in The Cultures of Creationism, philosopher of science Michael Ruse discussed EAAN. He argued:
That the EAAN conflates methodological and metaphysical naturalism.
That "we need to make a distinction that Plantinga fudges" between
"the world as we can in some sense discover" and "the world in some
absolute sense, metaphysical reality if you like." Then, "Once this
distinction is made, Plantinga's refutation of naturalism no longer
seems so threatening."
That "It is certainly the case that organisms are sometimes deceived
about the world of appearances and that this includes humans. Sometimes
we are systematically deceived, as instructors in elementary psychology
classes delight in demonstrating. Moreover, evolution can often give
good reasons as to why we are deceived." We know there are
misconceptions arising from selection as we can measure them against
reliable touchstones, but in Plantinga's hypothesised deceptions we are
deceived all the time which is "not how evolution's deceptions work".
He comments that in Plantinga's thinking we have confusion between the
world as we know it, and the world as it might be knowable in some
ultimate way, but "If we are all in an illusion then it makes no sense
to talk of illusion, for we have no touchstone of reality to make
absolute judgements."
Ruse concluded his discussion of the EAAN by stating:
To be honest, even if Plantinga's argument [the EAAN]
worked, I would still want to know where theism ends (and what form this
theism must take) and where science can take over. Is it the case that
evolution necessarily cannot function, or it is merely false and in
another God-created world it might have held in some way — and if so, in
what way? Plantinga has certainly not shown that the theist must be a
creationist, even though his own form of theism is creationism.
C. S. Lewis framing
Supposing
there was no intelligence behind the universe, no creative mind. In
that case, nobody designed my brain for the purpose of thinking. It is
merely that when the atoms inside my skull happen, for physical or
chemical reasons, to arrange themselves in a certain way, this gives me,
as a by-product, the sensation I call thought. But, if so, how can I
trust my own thinking to be true? It's like upsetting a milk jug and
hoping that the way it splashes itself will give you a map of London.
But if I can't trust my own thinking, of course I can't trust the
arguments leading to atheism, and therefore have no reason to be an
atheist, or anything else. Unless I believe in God, I cannot believe in
thought: so I can never use thought to disbelieve in God.
Plantinga's 2008 formulation of the argument
In the 2008 publication Knowledge of God Plantinga presented a formulation of the argument that solely focused on semantic epiphenomenalism instead of the former four jointly exhaustive categories.
Plantinga stated that from a materialist's point of view a belief
will be a neuronal event. In this conception a belief will have two
different sorts of properties:
electro-chemical or neurophysiological properties (NP properties for short)
and the property of having content (It will have to be the belief that p, for some proposition p).
Plantinga thought that we have something of an idea as to the history
of NP properties: structures with these properties have come to exist
by small increments, each increment such that it has proved to be useful
in the struggle for survival. But he then asked how the content property of a belief came about: "How does it [the content] get to be associated in that way with a given proposition?"
He said that materialists offer two theories for this question: According to the first, content supervenes upon NP properties; according to the second, content is reducible to
NP properties. (He noted that if content properties are reducible to NP
properties, then they also supervene upon them.) He explained the two
theories as follows:
Reducibility: A belief is a disjunction of conjunctions of NP properties.
Strong Supervenience (S+): For any possible worlds W and W* and any structures S and S*, if S has the same NP properties in W as S* has in W*, then S has the same content in W as S* has in W*. Supervenience can either be broadly logical supervenience or nomic supervenience.
Plantinga argued that neural structures that constitute beliefs have content,
in the following way: "At a certain level of complexity, these neural
structures start to display content. Perhaps this starts gradually and
early on (possibly C. elegans [a small worm with a nervous system
composed of only a few neurons] displays just the merest glimmer of
consciousness and the merest glimmer of content), or perhaps later and
more abruptly; that doesn't matter. What does matter is that at a
certain level of complexity of neural structures, content appears. This
is true whether content properties are reducible to NP properties or
supervene on them."
So given materialism some neural structures at a given level of
complexity acquire content and become beliefs. The question then is
according to Plantinga: "what is the likelihood, given materialism, that the content that thus arises is in fact true?"
This way of proceeding replaced the first step of Plantinga's earlier versions of the argument.
Criticism by eliminative materialists
The
EAAN claims that according to naturalism, evolution must operate on
beliefs, desires, and other contentful mental states for a biological
organism to have a reliable cognitive faculty such as the brain. Eliminative materialism
maintains that propositional attitudes such as beliefs and desires,
among other intentional mental states that have content, cannot be
explained on naturalism and therefore concludes that such entities do
not exist. It is not clear whether the EAAN would be successful against a
conception of naturalism which accepts eliminative materialism to be the correct scientific account of human cognition.
EAAN, intelligent design and theistic evolution
In his discussion of EAAN, Michael Ruse described Plantinga as believing in the truth of the attack on evolution presented by intelligent design advocate Phillip E. Johnson, and as having endorsed Johnson's book Darwin on Trial. Ruse said that Plantinga took the conflict between science and religion
further than Johnson, seeing it as not just a clash between the
philosophies of naturalism and theism, but as an attack on the true
philosophy of theism by what he considers the incoherent and
inconsistent philosophy of naturalism.
Plantinga has stated that EAAN is not directed against "the
theory of evolution, or the claim that human beings have evolved from
simian ancestors, or anything in that neighborhood". He also claimed that the problems raised by EAAN do not apply to the conjunction of theism and contemporary evolutionary science. In his essay Evolution and Design Plantinga outlines different ways in which theism and evolutionary theory can be combined.
In the foreword to the anthology Naturalism Defeated? James Beilby wrote: "Plantinga's argument should not
be mistaken for an argument against evolutionary theory in general or,
more specifically, against the claim that humans might have evolved from
more primitive life forms. Rather, the purpose of his argument is to
show that the denial of the existence of a creative deity is
problematic."
- Far Ultraviolet Camera/Spectrograph on Apollo 16 (April 1972)
- Orion 1 and Orion 2 Space Observatories (#1: 200-380 nm, 1971; #2: 200-300 nm, 1973)
- Astronomical Netherlands Satellite (150-330 nm, 1974–1976)
- International Ultraviolet Explorer (115-320 nm, 1978–1996)
- ROSAT XUV[5] (17-210eV) (30-6 nm, 1990–1999)
- Hisaki (130-530 nm, 2013 -)
- Lunar-based ultraviolet telescope (LUT) (on Chang'e 3 lunar lander, 245-340 nm, 2013 -)
- Astrosat (130-530 nm, 2015 -)
