Introduction
Plantinga: My
overall thesis: there is superficial conflict but deep concord between science
and religion, and superficial concord but deep conflict between naturalism and
science.[1]
à
This chapter is dedicated to defending the second half of this claim.
I. Superficial Concord
Plantinga: On
balance, theism is vastly more hospitable to science than naturalism, a much
better home for it. Indeed, it is theism, not naturalism, that deserves to be
called “the scientific worldview.”[2]
II. Deep Conflict
Plantinga:
[T]here is deep and irremediable conflict between naturalism and evolution –
and hence between naturalism and science.[3]
Plantinga: What I
will argue is that naturalism is in
conflict with evolution, a main pillar of contemporary science. And the
conflict in question is not that they can’t both be true (the conflict is not
that there is contradiction between them); it is rather that one can’t sensibly
accept them both.[4]
III. The Argument
Plantinga: My
argument will center on our cognitive
faculties: those faculties, or powers, or processes that produce beliefs or
knowledge in us. Among these faculties is memory,
whereby we know something of our past. There is also perception, whereby we know something about our physical
environment – for the most part our immediate environment, but also something
about distant objects such as the sun, the moon, and stars. Another is what is
often called “a priori intuition,” by
virtue of which we know truths of elementary arithmetic and logic.[5]
Plantinga also recognizes other faculties, including:[6]
(1) Sympathy
(2) Introspection
(3) Testimony
(4) Induction
(5) Moral
sense
(6) Sensus divinatis (sense of the divine)
Plantinga: My
argument will concern the reliability of these cognitive faculties. My memory,
for example, is reliable only if it produces mostly true beliefs – if, that is,
most of my memorial beliefs are true.[7]
Plantinga: What
proportion of my memorial beliefs must be true for my memory to be reliable?
We
can speak of the reliability of a
particular faculty – memory, for example – but also of the reliability of the
whole battery of our cognitive faculties. And indeed we ordinarily think our
faculties are reliable, at any rate
when they are functioning properly, when there is no cognitive malfunction or
disorder or dysfunction…We also think they are more reliable under some
circumstances than others. Visual perception of middle-sized objects…close at
hand is more reliable than perception of very small objects, or middle-sized
objects at some distance…Beliefs about where I was yesterday are ordinarily
more likely to be true than the latest high-powered scientific theories…Now the
natural thing to think, from the perspective of theism, is that our faculties
are indeed for the most part reliable, at least over a large part of their
range of operations. According to theistic religion (see chapter 9), God has
created us in his image; an important part of this image consists in our
resembling God in that like him, we can have knowledge.[9]
This, as we’ve discussed before, is an adaptation of a
Cartesian argument, which goes like this:
Descartes
writes in the Meditations, “When we
say...with respect to the body suffering from dropsy, that it has a disordered
nature because it has a dry throat and yet does not need drink, the term
'nature' is here used merely as an extraneous label. However, with respect to
the composite, that is, the mind united with this body, what is involved is not
a mere label, but a true error of nature, namely that it is thirsty at a time
when drink is going to cause it harm. It thus remains to inquire how it is that
the goodness of God does not prevent nature, in this sense, from deceiving us”
(CSM II, 59). He continues later, “[Notwithstanding] the immense
goodness of God, the nature of man as a combination of mind and body is such
that it is bound to mislead him from time to time...Yet it is much better that
it should mislead him [on the occasion of some sickness] than that it should
always mislead when the body is in good health” (CSM II, 61). He continues
further with suggestions toward how we may even learn to cope with and correct
such errors: “[In] matters regarding the well-being of the body, all of my senses
report the truth much more frequently than not. Also, I can almost always make
use of more than one sense to investigate the same thing; and in addition, I
can use both my memory, which connects present experiences with preceding ones,
and my intellect, which has by now examined all the causes of error” (CSM II, 61). “In the case of our clearest
and most careful judgments, however, this kind of explanation would not be
possible, for if such judgments were false they could not be corrected by any
clearer judgments or by means of any natural faculty. In such cases I simply
assert that it is impossible for us to be deceived. Since God is the supreme
being, he must also be supremely good and true, and it would therefore be a
contradiction that anything should be created by him which positively tends
towards falsehood...Hence this faculty must tend towards the truth, at least
when we use it correctly (that is, by assenting only to what we clearly and
distinctly perceive...)” (CSM II, 102-103).
Q1: How important
do you think it is that God, assuming he created us, created us with cognitive
faculties that are reliable in Plantinga’s sense, i.e., as yielding at least 3
times as many true beliefs as false beliefs? What would be the implications of
assuming him to have created us with merely adaptive (rather than materially
true) beliefs?
Plantinga: But
suppose you are a naturalist: you think that there is no such person as God,
and that we and our cognitive faculties have been cobbled together by natural
selection. Can you then sensibly think that our cognitive faculties are for the
most part reliable?[10]
à
I say you can’t. The basic idea of my argument could be put (a bit crudely) as
follows. First, the probability of our cognitive faculties being reliable, given
naturalism and evolution, is low…But then according to the second premise of my
argument, if I believe both naturalism and evolution, I have a defeater for my
intuitive assumption that my cognitive faculties are reliable. If I have a
defeater for that belief, however,
then I have a defeater for any belief I take to be produced by my cognitive
faculties. That means that I have a defeater for my belief that naturalism and
evolution are true. So my belief that naturalism and evolution are true gives
me a defeater for that very belief; that belief shoots itself in the foot and
is self-referentially incoherent; therefore, I cannot rationally accept it. And
if one can’t accept both naturalism and evolution, that pillar of current
science, then there is serious conflict between naturalism and science.[11]
Plantinga: [From naturalist perspective,] what evolution
guarantees is (at most) that we behave in certain ways – in such ways as to
promote survival, or more exactly reproductive success. The principal function or
purpose, then, (the “chore” says Churchland) of our cognitive faculties is not
that of producing true of verisimilitudinous (nearly true) beliefs, but instead
that of contributing to survival by getting the body parts in the right place.
What evolution underwrites is only (at most) that our behavior is reasonably adaptive to the circumstances in which our
ancestors found themselves; hence it does not guarantee mostly true or
verisimilitudinous beliefs…What Churchland therefore suggests is that
naturalistic evolution…gives us reason to doubt two things: (a) that a purpose of our cognitive systems is that
of serving us with true beliefs, and (b) that they do, in fact, furnish us
with mostly true beliefs.[12]
Q2: Let’s grant
that the naturalist has no reason to believe that his faculties are reliable in
Plantinga’s sense, i.e., as yielding at least 3 times as many true beliefs as
false beliefs. Assume he is required to replace this premise with the premise
that his faculties are reliable only in the sense of generating beliefs that
are adaptive. What follows? What should be the naturalist’s attitude toward
N&E? Should he believe it? Why or why not? If he did, would his belief be
rational? Why or why not?
Recall that, for the naturalist, belief must be given a different
analysis than Plantinga has used, too. Belief for the naturalist is presumably
not to be taken as the correspondence theory construes it; it may just denote
some sort of adequacy for all associated practical functions, as James analyzes
it.
James’ Pragmatic
Conception of Truth –
‘The true’, to put it very briefly, is only the expedient in
the way of our thinking, just as ‘the right’ is only the expedient in the way
of our behaving. Expedient in almost any fashion; and expedient in the
long run and on the whole, of course. (1907: 106)
Ideas …
become true just in so far as they help us to get into satisfactory relations
with other parts of our experience. (1907: 34)
Any idea upon which we can ride …; any idea that will carry us
prosperously from any one part of our experience to any other part, linking
things satisfactorily, working securely, saving labor; is true for just so
much, true in so far forth, true instrumentally. (1907: 34)
Q3: On James’
“pragmatic conception of truth,” and a corresponding analysis of belief
(perhaps Schellenberg’s below?) and reliability, would the naturalist still be irrational
in “believing” N&E? Why or why
not?
Schellenberg’s
Account of Acceptance –
The
basic distinction here between acceptance and belief I take over from L.
Jonathan Cohen’s marvelous little treatise on the subject, though on details I
differ with him.[13]
The fundamental idea is that acceptance is voluntary while belief is not. To
accept that p is to, as a matter of policy, employ that proposition as a
premise in relevant reasoning, whereas believing that p is or includes an
involuntary disposition to (as one might say) be appeared to p-ly.[14]
Here
we see one of the clear differences between propositional faith and
propositional belief. When I have faith, I consciously and deliberately don a
pair of glasses that give everything – or at least the relevant things – a
certain hue (and it may be difficult to keep the glasses on). I know that it is
the glasses that produce this effect, while not denying that it might match
what I would see without glasses if my vision were sufficiently penetrating.
The experience of belief, on the other hand, is like wearing the glasses
without knowing it (and here, of course, there can be no associated difficulty,
for the representation is not voluntarily produced).[15]
Q4: If the
naturalist “accepts” rather than “believes” N&E, can he avoid the
irrationality charge? Why or why not?
Q5: Should we
even accept Plantinga’s claim that evolutionary
theory provides us with no reason to think that our cognitive faculties are
reliable (i.e., yield mostly true beliefs)? How might we evaluate this claim?
What criteria might we use in order to determine if a particular trait is to be
expected given evolutionary theory?
IV. The First Premise: Darwin’s Doubt
Darwin’s doubt –
The conditional probability of one proposition p on another proposition q is
the probability that p is true given that, on the condition that, q is
true…[T]he conditional probability that our cognitive faculties are reliable,
given naturalism together with the proposition that we have come to be by way
of evolution, is low.
Q6: Do you think
there’s a way around premise (1)? If so, what are some possible solutions?
Weaker EAN –
[In
this chapter,] we are speaking of all
our cognitive faculties. But perhaps there are interesting distinctions to be
made among them. Perhaps some are less likely than others to be reliable, given
N&E. perhaps those faculties that produce beliefs that appear to be relevant
to survival and reproduction are more likely to be reliable than those
faculties that produce beliefs of other kinds. For example, one might think
that perceptual beliefs are often more likely to be relevant to adaptive
behavior than beliefs about, say, art criticism, or postmodernism, or string
theory.[17]
Adjusting the argument to accommodate the considerations
above, we might reformulate (1) as follows:
(1*)
P(MR/N&E) is low[18]
But, argues Plantinga, since N is a presumably a metaphysical belief, which is only
weakly (if at all) relevant to our survival and reproduction, the argument
yields the same result.
Plantinga’s Chief
Criterion for Reliability – Those faculties that produce beliefs that
appear to be relevant to survival and reproduction are more likely to be
reliable than those faculties that produce beliefs of other kinds.
Q7: Why might the
criterion identified by Plantinga not
be the most relevant criterion in judging how likely it is that a particular
faculty be reliable? What other criteria might be more relevant to the question of whether a particular faculty is
likely to be reliable?
A. Naturalism and Materialism
In this section, Plantinga argues that we should interpret
naturalism as entailing materialism about human beings.[19]
Q8: Do you agree
that naturalism does, or should, entail materialism about human beings? Why or
why not?
B. Beliefs as Neural Structures
Plantinga: Now
what sort of thing will a belief be, from this materialist perspective?
à
[I]t would have to be something like a long-standing event or structure in your
brain or nervous system. Presumably this event will involve many neurons
connected to each other in various ways…So (from the naturalist’s point of
view) a belief will be a neuronal event or structure of this sort, with input
from other parts of the nervous system and output to still other parts as well
as to muscles and glands. But if this is the sort of thing beliefs are…they
will have two quite different sorts of properties. On the one hand they will
have electro-chemical or neurophysiological properties (NP
properties, for short)…But if the event in question is really a belief, then in addition to those NP
properties it will have another property as well: it will have a content. It will be the belief that p,
for some proposition p.[20]
Plantinga: It is
in virtue of having content that a belief is true or false: it is true if the
proposition which is its content is true, and false otherwise.[21]
Q9: Do you
satisfied with Plantinga’s construal of the materialist analysis of belief? Why
or why not?
Cosmides’ and Tooby’s
Notion of Architectural Truth –
We believe that there are a large number of
design innovations that have evolved to solve the specialized programming
problems posed by using local and contingent information, including a
specialized scope syntax, metarepresentational adaptations, and decoupling
systems. Indeed, we think that the human cognitive architecture is full of
interlocking design features whose function is to solve problems of scope and
accuracy. Examples include truth-value tags, source-tags (self vs. other;
vision vs. memory, etc.), scope-tags, time and place tags, reference-tags,
credal values, operators embodying propositional attitudes, content-based
routing of information to targeted inference engines, dissociations, systems of
information encapsulation and interaction, independent representational formats
for different ontologies, and the architecture and differential volatility of
different memory systems. One critical feature is the capacity to carry out
inferential operations on sets of inferences that incorporate suppositions or
propositions of conditionally unevaluated truth value, while keeping their
computational products isolated from other knowledge stores until the truth or
utility of the suppositions is decided, and the outputs are either integrated
or discarded. This capacity is essential to planning, interpreting,
communicating, employing the information communication brings, evaluating
others' claims, mind-reading, pretense, detecting or perpetrating deception,
using inference to triangulate information about past or hidden causal
relations, and much else that makes the human mind so distinctive.
In what follows, we will try to
sketch out some of the basic elements of a scope syntax designed to defuse
problems intrinsic to the human mode of intelligence. By a scope syntax, we
mean a system of procedures, operators, relationships, and data handling
formats that regulate the migration of information among subcomponents of the
human cognitive architecture.
…To clarify what we mean,
consider a simple cognitive system that we suspect is the ancestral
condition for all animal minds, and the default condition for the human mind as
well: naïve realism. For the naïve realist, the world as it is mentally
represented is taken for the world as it really is, and no distinction is drawn
between the two. Indeed, only a subset of possible architectures are even
capable of representing this distinction, and in the origin and initial
evolution of representational systems, such a distinction would be
functionless. From our external perspective, we can say of such basic
architectures that all information found inside the system is assumed to be
true, or is treated as true. However, from the point of view of the
architecture itself, that would not be correct, for it would imply that the
system is capable of drawing the distinction between true and false, and is
categorizing the information as true. Instead, mechanisms in the architecture
simply use the information found inside the system to regulate behavior and to
carry out further computations. Whatever information is present in the system
simply is "reality" for the architecture. Instead of tagging
information as true or false - as seems so obvious to us - such basic
architectures would not be designed to store false information. When new
information is produced that renders old information obsolete, the old
information is updated, overwritten, forgotten, or discarded. None of these
operations require the tagging of information as true or false. They only
involve the rule-governed replacement of some data by other data, just like
overwriting a memory register in a personal computer does not require the data
previously in that register be categorized as false. For most of the
behavior-regulatory operations that representational systems evolved to
orchestrate, there would be no point to storing false information, or
information tagged as false. For this reason, there is no need in such an
architecture to be able to represent that some information is true: its
presence, or the decision to store it or remember it, is the cue to its
reliability. In such a design, true equals accessible.
With this as background, and leaving aside
the many controversies in epistemology over how to conceptualize what truth
"really" is, we can define what we will call architectural
truth: information is treated by an architecture as true when it is
allowed to migrate (or be reproduced) in an unrestricted or scope-free fashion
throughout an architecture, and is allowed to interact with any other data in
the system that it is capable of interacting with. All data in semantic memory,
for example, is architecturally true. The simplest and most economical
way to engineer data use is for "true" information to be unmarked,
and for unmarked information to be given whatever freedom of movement is
possible by the computational architecture. Indeed, any system that
acquires, stores, and uses information is a design of this kind. The
alternative design, in which each piece of information intended to be used must
be paired with another piece of information indicating that the first piece is
true, seems unnecessarily costly and cumbersome. Because the true-is-unmarked
system is the natural way for an evolved computational system to originate, and
because there are many reasons to maintain this system for most uses, we might
expect that this is also the reason why humans, and undoubtedly other
organisms, are naïve realists. Naïve realism seems to be the likely starting
point phylogenetically and ontogenetically, as well as the default mode for
most systems, even in adulthood.
Plantinga: Given
materialism, therefore, beliefs are (ordinarily) long-standing neural events.
As such, they have NP properties, but also content properties…NP properties are
physical properties; on the other
hand, content properties…are mental
properties. Now how, according to materialism, are mental and physical
properties related? In particular, how are content properties related to NP
properties – how is the content property of a particular belief related to the
NP properties of that belief?[22]
Q10: Is something
like the mind-body problem inherent to every
theory of mind, i.e., to materialism as well as to dualism? Is the materialist’s
problem of explaining how physical structures or events give rise to mental
events as serious as the dualist’s problem of explaining how immaterial
substance causally interacts with physical substance?
Schellenberg’s
Account of Belief –
From
the fact that my belief is expressed propositionally it does not follow that
when I believe, I have a proposition before my mind and am directing some sort
of affirming attitude toward that. And
when we look carefully at what is actually going on in conscious belief, we can
observe that this is in any case false: I am not, one wants to say, thinking of
a proposition and under the impression that it is true; rather, I am thinking
of a state of affairs and under the impression that it obtains…[O]ne can think
of a state of affairs without believing. What is the “certain characteristic
way” of having such a thought which brings us all the way to belief?...[T]he
believer, when it comes right down to it, is simply thinking of the world. (Notice that the world is real by
definition; thus if the world is
thought of by someone, there is no way for the question to arise whether he is
not after all thinking of things in a detached way, perhaps in imaginative
reveries, and thus in a manner implying or consistent with nonbelief.)…It is
striking that what the experience of believing really comes down to is simply
thinking of the world – no mention of property attribution or of assent or of
an extra feeling component that so many (following Hume) have sought to put
their finger on will seem tempting to the analyst, once it is seen that
correctly identifying the object of
the believing thought gives us everything we need. That elusive “characteristic
way” in which the believer is supposed to be related to the object of her
belief is nothing but a reflection of the object itself.[23]
A
belief in p is a disposition to “feel it true” that p.[24]
C. Reductive and Nonreductive Materialism
Reductive materialism
– Mental content properties are reducible
to NP properties.[25]
Nonreductive materialism
– Content properties are not reducible to NP properties, but are determined by
(supervene on) NP properties.[26]
So-called eliminative
materialists, or eliminativists
(like the Churchlands), reject the idea that such things as beliefs, desires,
etc. really exist, at least as commonly conceived. They suggest instead that
they are folk concepts that will eventually be replaced once science has
determined the actual physical structures and processes that underlie them.
Modern
versions of eliminative materialism claim that our common-sense understanding
of psychological states and processes is deeply mistaken and that some or all
of our ordinary notions of mental states will have no home, at any level of
analysis, in a sophisticated and accurate account of the mind. In other words,
it is the view that certain common-sense mental states, such as beliefs and
desires, do not exist.[27]
Plantinga: [W]hat
is the likelihood, given evolution and
naturalism (construed as including materialism about human beings), that
the content thus arising is in fact true?
In particular, what is the likelihood, given N&E, that the content
associated with our neural structures
is true? What is the likelihood, given N&E, that our cognitive faculties
are reliable, thereby producing mostly true beliefs?[28]
à
Very low.
Q11: Should
naturalists accept Plantinga’s framing of the problem? Neither Plantinga’s
account of reliability nor his account of truth are very amenable to
naturalism, so shouldn’t any argument intended to draw absurd implications from
the naturalist view incorporate accounts of reliability and truth that are
actually amenable to that view? Is Plantinga’s problem even susceptible to a
naturalist-friendly formulation, or does the problem disappear entirely when
framed in purely naturalistic terms?
Q12: Does
contemporary epistemology already preclude (particularly reductive) materialist
analyses? In other words, do you think that contemporary epistemology provides
the conceptual and terminological resources it needs to address the most
important epistemological questions in a thoroughly reductive materialist way?
V. The Argument for Premise (1)
A. The Argument and Nonreductive Materialism
Plantinga: The NP
properties are selected…not because they cause the content they do, but because
they cause adaptive behavior.
Objection –
consider a frog on a lily pad. A fly buzzes by; the frog’s tongue flicks out
and captures the fly. If this frog is to behave successfully, adaptively, there
must be mechanisms in it that register the distance to the fly at each moment,
its size, speed, and direction, and so on. Aren’t these mechanisms part of the
frog’s cognitive faculties? And don’t they have to be accurate in order for the
frog to behave adaptively? And isn’t it therefore the case that the frog’s
cognitive mechanisms must be accurate, reliable, if the frog is to survive and
reproduce?[29]
à
Plantinga: [T]hat frog clearly does
have “indicators,” neural structures that receive input from the frog’s sense
organs, are correlated with the path of the insect as it flies past, and are
connected with the frog’s muscles in such a way that it flicks out its tongue
and captures that unfortunately fly…[But] indication of this sort does not
require belief. In particular, it
does not require belief having to do with the state of affairs indicated;
indeed it is entirely compatible with belief inconsistent with that state of affairs.[30]
Fleeing
predators, finding food and mates – these things require cognitive devices that
in some way track crucial features of the environment, and are appropriately
connected with muscles; but they do not require true belief, or even belief at
all. The long-term survival of organisms of a certain species certainly makes
it likely that its members enjoy cognitive devices that are successful in
tracking those features of the environment – indicators, as I’ve been calling
them. Indicators, however, need not be or involve beliefs.[31]
Indication
is one thing; belief content is something else altogether, and we know of no
reason (given materialism) why the one should follow the other. We know of no
reason why the content of a belief should match what the belief (together,
perhaps, with other structures) indicates. Content simply arises upon the
appearance of neural structures of sufficient complexity; there is no reason
why that content need be related to what the structures indicates, if anything.
Indeed, the proposition constituting that content need not be so much as about that predator; it certainly need
not be true.[32]
Q13: Is it true
that “we know of no reason why the
content of a belief should match what the belief indicates” (emphasis mine)?[33]
What about our knowledge of what our ancestral environment was like? Or our
knowledge how natural selection works? Do either of these provide us with reasons to think that the content of a belief
might match what the belief indicates (e.g., by suggesting certain criteria by
which the likelihood of a particular trait evolving might be)?
To say that indication of this sort does not require belief does not imply that any
other alternative (e.g., one in which content is entirely excluded, or in which
the belief is inconsistent with the state of affairs) is equally likely, i.e.,
given N&E. It may very well be – and perhaps evolutionary theory even
predicts this – that the indication function is most likely to have evolved
and/or function successfully on a design plan that incorporates a reliable
(truth-aimed) faculty.
Q14: Do you think
that it is plausible to suppose, as Plantinga seems to, that any of the alternative design plans
mentioned above is equally likely to evolve given N&E? Why or why not?
Q15: How might we
get adaptive behavior without, or
independently of the facilitation provided by, (mechanisms or faculties that
produce) true content?
Plantinga: The
fact that these creatures have survived and evolved, that their cognitive
equipment was good enough to enable their ancestors to survive and reproduce –
that fact would tell us nothing at all about the truth of their beliefs or the reliability
of their cognitive faculties...[the content of their beliefs] might be true,
but might with equal probability be false. So shouldn’t we suppose that the
proposition in question has a probability of roughly .5?...That would seem the
sensible course. Neither seems more probable than the other; hence we should
estimate the probability of its being true as .5…The probability we are
thinking of it objective, not the personalist’s subjective probability, and
also not epistemic probability.[34]
Plantinga: If I
have 1,000 independent beliefs, for example, the probability (under these
conditions) that three quarters or more of these beliefs are true will be less
than 10-58….So the chances that this creature’s true beliefs substantially
outnumber its false beliefs are small. The conclusion to be drawn is that it is
very unlikely that the cognitive faculties of those creatures are reliable. [35]
Q16: Why think
that these probabilities are equal? Why think that they represent objective probabilities rather than subjective, or epistemic probabilities? How might someone go about calculating
these probabilities?
B. The Argument and Reductive Materialism
…(Nothing much to say here)
C. Objection
Objection: Isn’t
it just obvious that true beliefs will facilitate adaptive action? A gazelle
who mistakenly believes that lions are friendly, overgrown house cats won’t be
long for this world…Isn’t it obvious, more generally, that true beliefs are
more likely to be successful than false beliefs?[36]
à
Yes, certainly. This is indeed true. But it is also irrelevant. We are not
asking about how things are, but
about what things would be like if
evolution and naturalism (construed as including materialism) were true…The
question is what things would be like if N&E were true; and in this context
we can’t just assume, of course, that if N&E, N including materialism, were
true, then thing would still be the way they are. That is, we can’t assume that
if materialism were true, it would still be the case that true beliefs are more
likely to cause successful action than false beliefs. And in fact, if
materialism were true, it would be unlikely that true beliefs mostly cause
successful action and false belief unsuccessful action.[37]
Objection: Why
think a thing like that? What has materialism got to do with the question?
à
Here’s what. We ordinarily think true belief leads to successful action because
we also think that beliefs cause (part-cause) actions, and do so by virtue of their content…But now
suppose materialism were true: then, as we’ve seen, my belief will be a neural
structure that has both NP properties and also a propositional content. It is
by virtue of the NP properties, however, not the content, that the belief
causes what it does cause. It is by virtue of those properties that the belief causes neural impulses to travel
down the relevant efferent nerves to the relevant muscles causing them to
contract, and thus causing behavior. It isn’t by virtue of the content of this
belief; the content of the belief is irrelevant to the causal power of the
belief with respect to the behavior.[38]
Q17: How is it,
on the nonreductive materialist account that Plantinga is using to frame this
problem, that the content of the belief is supposed to be “irrelevant to the
causal power of the belief with respect to the behavior”? Is Plantinga
imagining the truth of the content of the NPs to be accidental to their
functioning in this capacity? How would that work structurally? If this were
the case, why should NP properties ever have evolved the ability to determine
content properties (much less, content properties that are true)?
Objection: You
claim that
(1) If
the belief B had had the same NP properties but different content, it still
would have had the same causal effects with respect to behavior;
But
it couldn’t have had the same NP
properties but different content. (1) is not merely counterfactual; it’s
counterpossible.[39]
à
Plantinga: [Usual semantics for counterfactual notwithstanding, the] truth
of (1) gives us some reason to think that B doesn’t cause that action A by
virtue of its content…It is [rather] by virtue of its neurological properties
that B causes A; it is by virtue of those
properties that B sends a signal along the relevant nerves to the relevant
muscles, causing them to contract, and thus causing A. It isn’t by virtue of
its having that particular content C that it causes what it does cause.[40]
Q18: What do you
think of Plantinga’s response to the objection above?
VI. The Remaining Premises
Plantinga: [T]he
naturalist who sees that P(R/N&E) is low has a defeater for R, and for the proposition that his own cognitive
faculties are reliable. A defeater for a belief B I hold – at any rate this
kind of defeater – is another belief B* I come to hold which is such that,
given that I hold B*, I can no longer rationally hold B.[41]
Plantinga: It
isn’t that someone who believes N&E wouldn’t have enough evidence for R to believe it rationally.
The fact is I don’t need evidence for
R. That’s a good thing, because it isn’t possible to acquire evidence for T, at
least if I have any doubts about it.[43]
Q19: Why isn’t it
possible to acquire evidence for R? What does having doubts about R have to do
with the impossibility of acquiring evidence?
à
Plantinga: My accepting any argument
for R, or any evidence for it, would clearly presuppose my believing R; any
such procedure would therefore be viciously circular.[44]
Objection: Why
should we think that premise (2) is true? Some propositions of that form are
true, but some aren’t.
à
Plantinga: Right: not every
proposition of that form is true. This one is, however. What’s at issue, I
think, is the question what else I believe (more exactly what else is such that
I believe it and can legitimately conditionalize on it in this context).[45]
Plantinga: But
now think about N&E and R. We agree that P(R/N&E) is low. Do I know
something else, in addition to N&E, such that (a) I can properly
conditionalize on X, and (b) P(R/N&E&X) is high? This is the
conditionalization problem, which I address briefly on pages [357-358].[46]
(3) Anyone
who has a defeater for R has a defeater for any other belief she thinks she
has, including N&E itself.[47]
Q20: Might not
the apparent fact that our beliefs lead us into reasonably fruitful
interactions with the world provide us with a reason to believe that, despite
Plantinga’s concerns, our faculties are nonetheless reliable, at least in
relevant sense? In other words, is a Kantian defense of the reliability of our
faculties, grounded in their practical efficacy, possible here?
Q21: How about
the possibility that the truth of certain beliefs, e.g., those in the
elementary arithmetic and logic, is self-evident?
Is it even possible to seriously doubt the reliability of the faculty(/ies)
that produces these beliefs? If not, does this knowledge raise the probability
of R(N&E)?
(4) If
one accepts N&E thereby acquires a defeater for N&E, N&E is
self-defeating and can’t rationally be accepted.
Plantinga: Is
there any sensible way at all in which [someone] can argue for R?
à
It is hard to see how. Any argument she might produce will have premises; these
premises, she claims, give her good reasons to believe R. But of course she has
the very same defeater for each of those premises that she has for R, and she
has the same defeater for the belief that if the premises of that argument are
true, then so is the conclusion…This defeater, therefore, can’t be defeated.
Hence the devotee of N&E has an undefeated defeater for N&E.[48]
Summary
(1) P(R/N&E)
is low
(2) Anyone
who accepts (believes) N&E and sees that (P/R N&E) is low has a
defeater for R.
(3) Anyone
who has a defeater for R has a defeater for any other belief she thinks she
has, including N&E itself.
(4) If
one accepts N&E thereby acquires a defeater for N&E, N&E is
self-defeating and can’t rationally be accepted.
à
Conclusion: N&E can’t be rationally accepted.
What Plantinga’s argument amounts to is a rejection of a
non-theistic foundational epistemology. He is basically reaffirming Descartes’
thesis that the only possible
foundation for justifying our claims of possessing knowledge, whether empirical
or a priori, is an assurance (or perhaps simply assumption) of God’s existence.
Q22: Assuming
that the naturalist even cares to safeguard his claim to possess knowledge,
what foundation besides the assumption that his faculties are reliable might be
available to him? Is it evolutionary theory that generates this problem? Is
there another account besides either evolution or divine creation that might
still serve to safeguard our claims to possess knowledge?
VII. Two Concluding Comments
Plantinga: The
naturalist might have a defeater deflector, i.e., a belief that together with
N&E serves to raise the probability of R to high…[I]s there are a defeater
deflector for the defeat of R threatened by N&E and P(R/N&E) is low?
à
Well, it certainly looks as if there are: what about R itself? That’s
presumably something the naturalist believes…But of course R itself isn’t a
proper candidate for being a defeater deflector here. If a belief A could itself be a defeater-deflector for a
putative defeater of A, no belief could ever be defeated.[49]
[1] P. 317.
[2] P. 319.
[3] P. 319-320.
[4] P. 320.
[5] p. 321-322.
[6] P. 322.
[7] P. 322.
[8] P. 323.
[9] P. 322-323.
[10] P. 323.
[11] P. 324.
[12] P. 325-326.
[13] See L. Jonathan Cohen, An Essay on Belief and Acceptance (Oxford: Clarendon Press, 1992).
My understanding of acceptance is in some ways closer to that of Gregory W.
Dawes in “Belief is not the Issue: A Defense of Inference to the Best
Explanation,” Ratio 26 (2013), 62-78.
[15] Schellenberg, J.L. Prolegomena to a Philosophy of Religion, 134.
[16] P. 327.
[17] P. 359.
[18] P. 360.
[19] P. 330.
[20] P. 331.
[21] P. 332.
[22] P. 332.
[23] Schellenberg, J.L. Prolegomena to a Philosophy of Religion, 47.
[24] Schellenberg, J.L. Divine Hiddenness and Human Reason, 30.
[25] P. 333.
[26] P. 333.
[28] P. 335.
[29] P. 337-338.
[30] P. 338.
[31] P. 339.
[32] P. 341.
[33] Consider also the alternatives to this formulation
discussed above. On Schellenberg’s account, Plantinga would have to say (roughly) that
“we know of no reason why the subjective representation of an object should
match the object as it objectively is.” But this formulation doesn’t seem nearly as
strong as the one he puts forward.
[34] P. 341.
[35] P. 343.
[36] P. 345.
[37] P. 345-346.
[38] P. 346.
[39] P. 347-348.
[40] P. 349.
[41] P. 350.
[42] P. 351.
[43] P. 351.
[44] P. 351.
[45] P. 353.
[46] P. 354.
[47] P. 354.
[48] P. 356.
[49] P. 357.
