Transcript The Cognitive Reliability Argument

The Cognitive Reliability
Argument
• An argument first proposed some
twelve years ago by philosopher Alvin
Plantinga of the University of Notre
Dame, who has since defended and
revised the argument
• Plantinga seeks to show that Naturalism
is self-defeating, and it is, therefore,
irrational to be a Naturalist.
• What is Naturalism?
– “[T]he belief that there aren’t any
supernatural beings – no such person
as God, for example, but also no other
supernatural entities, and nothing at all
like God.”
Alvin Plantinga, Introduction to Naturalism
Defeated?, p. 1
– Naturalism is, thus, the belief that
nothing exists beyond the world that, in
principle, can be studied by the natural
sciences, i.e. biology, chemistry,
physics, et al.
• Why is Naturalism Self-Defeating?
– Plantinga’s argument that Naturalism
is self-defeating centers around the
reliability of humans’ cognitive
capacities.
– What are humans’ cognitive
capacities?
• The mental and sensory capacities
humans use to form their beliefs.
– What does it mean for humans’
cognitive capacities to be reliable?
• Humans’ cognitive capacities are
reliable only if the content of a strong
majority of the beliefs humans form
using them are true, i.e. the content
corresponds to the way the world
really is.
– Plantinga argues that the probability
that humans’ cognitive capacities, given
Naturalism, are reliable, P(R/N), is either
low or inscrutable (i.e. unknowable).
– Either way, Plantinga claims, it is
unwarranted for anyone to accept as
true any belief produced by humans’
cognitive capacities, including
Naturalism itself.
– Accepting Naturalism, thus, gives one a
good reason to reject it making it selfdefeating.
– Since being self-defeating is sufficient
for a viewpoint’s being irrational,
Naturalism is an irrational viewpoint, and
no one can subscribe to it without
thereby becoming irrational himself.
– Plantinga’s whole argument rests on two
claims.
• Claim A: P(R/N) is either low or
inscrutable.
– Actually, Plantinga claims that the
probability that humans’ cognitive
capacities, given BOTH naturalism
AND Darwinian Evolution, are
reliable, P(R/N&E), is either low or
inscrutable.
– He also claims (correctly, in my view)
that Naturalism entails Darwinian
Evolution or something functionally
equivalent.
– Given this entailment, P(R/N&E)
is the same as P(R/N).
– Thus, to simply matters, we will
assume, along with Plantinga,
that Naturalism entails Darwinian
Evolution.
• Claim B: Given Claim A, it is
unwarranted for anyone to accept
as true any belief formed by
humans’ cognitive capacities,
including Naturalism itself.
• Plantinga’s argument for Claim A
– Plantinga begins with what he calls
Darwin’s Doubt.
• “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
anyone trust in the convictions of a
monkey’s mind, if there are any
convictions in such a mind?”
Charles Darwin, Letter to William Graham
Down – July 3, 1881
– What, Plantinga asks, is the source of
Darwin’s “horrid doubt?”
• According to Darwin’s evolutionary
theory, humans’ present cognitive
capacities, like every other capacity
they possess, is the result of natural
selection.
• Natural selection selects capacities,
not for their ability to produce true
beliefs, but for their ability to produce
adaptive behavior, i.e behavior that
results in the survival of the species.
• “[T]he fact that my behavior (or that of
my ancestors) has been adaptive is at
best a third-rate reason for thinking
my beliefs mostly true and my
cognitive faculties reliable.”
Alvin Plantinga, “An Evolutionary
Argument against Naturalism,” p. 10
– Adaptive Behavior and Reliable
Cognitive Capacities
• In order for adaptive behavior to be a
first-rate reason for believing cognitive
faculties reliable, this statement must
be true:
– A being (species) displays
adaptive behavior only if its
cognitive capacities are reliable.
• Plantinga argues there is no reason
to believe the italicized statement is
true, especially given Naturalism.
• Epiphenomenialism
– For our purposes, we can take
Epiphenomenialism to be the
view that the content of beliefs
plays no role in the production of
behavior.
– “According to [the December, 1992
issue of] Time, a few years ago the
eminent biologist J. M. Smith ‘wrote
that he never understood why
organisms have feelings. After all,
orthodox biologists believe that
behavior, however complex, is
governed entirely by biochemistry
and that the attendant sensations –
fear, pain, wonder, love – are just
shadows cast by that biochemistry,
not themselves vital to the organism’s
behavior.’”
Alvin Plantinga, “An Evolutionary Argument against
Naturalism,” p. 11
– Philosopher Robert Cummins
goes so far as to call the position
Smith enunciates the “received
view” among Naturalists.
– As Plantinga points out,
however, if feelings play no role
in the production of behavior,
including adaptive behavior, then
neither does the content of
beliefs.
– Since it’s the content of beliefs
that is true or false, if what Smith
claims is true, then a species’
displaying adaptive behavior is
not a good reason to believe its
cognitive capacities are reliable.
• The Efficacy of False Belief
– Let’s say that the “received
view” among Naturalist is wrong
and the content of beliefs does
play a role in producing behavior.
– Is there any reason, Plantinga
asks, to believe that the content
of the beliefs that produce
behavior has to be mostly true in
order for behavior to be
adaptive?
» No, says Plantinga.
» “Perhaps a primitive tribe
thinks that everything is really
alive, or is a witch, or a demon
of some sort;
» “and perhaps all or nearly all
of their beliefs are of the form:
This witch is F or that demon
is G; this witch is good to eat,
or that demon is likely to eat
me, if I give it a chance.
Clearly, these beliefs could be
adaptive while nonetheless
false.”
Alvin Plantinga, “An Evolutionary
Argument against Naturalism,” p.
10
» The Matrix
» ALL of the beliefs possessed by
the people in the Matrix are
false; yet, these beliefs produce
adaptive behavior.
» These false beliefs cause them
to lie in their vats of goo,
oblivious to the truth, but,
nonetheless, surviving.
» Indeed, as Morpheus points
out, that’s the reason the
machines feed them the false
beliefs.
– The upshot of all of this is that Darwin’s
“horrid doubt” is well-founded.
• Given Naturalism, there is no good
reason to believe the “convictions of
man’s mind” are reliable.
• This is so because the adaptive
behavior displayed by humans
provides no good reason to believe
their cognitive capacities are reliable.
• A very large number of false beliefs
will produce adaptive behavior just as
well as true beliefs.
– Perhaps, adaptive behavior requires
that a certain critical percentage of a
species’ beliefs be true.
– Still, there is no good reason to
believe that critical percentage comes
anywhere close to the strong majority
necessary to make the species’
cognitive capacities reliable.
– What’s more, complex (and
interesting) beliefs, e.g. Naturalism,
are very unlikely to be among the
critical percentage of true beliefs
necessary for adaptive behavior.
• Since a very large number of false
beliefs produces adaptive behavior
and there are many more false
beliefs than true ones, one can
argue the P(R/N) is low.
• The best one can say, given all of
the above, is that the P(R/N) can’t
be determine, i.e. that it is
inscrutable.
• Plantinga’s Argument for Claim B
– Given that P(R/N) is either low or
inscrutable, the Naturalist has a
defeater for R (i.e. the proposition that
humans’ cognitive capacities are
reliable).
– A defeater is a reason to doubt or not
believe a proposition.
– “Among the crucially important facts,
with respect to the question of the
reliability of a group of cognitive
faculties, are facts about their origin.
– “[S]uppose I come to believe that I
have been captured by AlphaCentaurian superscientists who have
made me the subject of a cognitive
experiment in which I have been given
mostly false beliefs [or suppose I
believe I am trapped in the Matrix] . . . .
[In either case,] I have a defeater for R.
But to have a defeater for R it isn’t
necessary that I believe that in fact I
have been . . . captured by those
Alpha-Centaurian superscientists
– “[or have become trapped in the
Matrix]. It suffices for me to have . . .
a defeater [for R that] I have
considered those scenarios, and the
probability that one of those scenarios
is true is inscrutable for me. It
suffices that I have considered those
scenarios, and for all I know or
believe, one of them is true.”
Alvin Plantinga, Introduction to Naturalism
Defeated?, p. 11
– The Naturalist is in the same
epistemic condition as the person
possibly captured by the AlphaCentuarian superscientists or the
person possibly trapped in the Matrix.
– This is so because, for all three, the
probability that their cognitive
capacities are reliable (or, if you
prefer, unreliable) is inscrutable.
– Thus, given Claim A, Claim B is also
true.
• Final Points
– Plantinga’s argument, assuming it is
sound, does not prove that Naturalism is
false.
– Rather, it proves that Naturalism is an
irrational viewpoint.
– Naturalism, Plantinga believes, is
Classical Theism’s biggest intellectual
competitor, at least in the West.
– So, while proving that Naturalism is
irrational does not prove that Classical
Theism is true, it does give Classical
Theism a big boost.
– What’s more, the probability that
humans’ cognitive capacities are
reliable give Classical Theism,
P(R/CT) is 1.
• “[A]ccording to [Classical Theism],
we human beings have been
created in the image of God. This
means, among other things, that
God created us with the capacity
for achieving knowledge . . . .”
Alvin Plantinga, Introduction to Naturalism
Defeated?, p. 2
• “Only in rational creatures is there
found a likeness of God which
counts as an image . . . . As far as
a likeness of the divine nature is
concerned, rational creatures seem
somehow to attain a representation
of [that] type in virtue of imitating
God not only in this, that He is and
lives, but, especially, in this, that He
understands.”
Saint Thomas Aquinas, Summa
Theologica I, 93, vi
– While Naturalism entails Darwinian
Evolution, it is NOT entailed by it.
• Classical Theism is consistent with
Darwinian Evolution.
• This is so because the random (i.e.
unpredictable) genetic mutations
that drive Darwinian Evolution can
be caused, orchestrated, and
arranged by God to result in the
eventual production of human
beings.