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Monday, 14 September 2015
Laurence Bonjour on the A Priori Links in a Quinean Web
can give an example of Laurence BonJour’s logical links between
beliefs in the Quinean web.
that we experience something which gets us to reject R above.
If that happened, then we must reject the conjunction P ∧ Q
because if P and Q are taken together they imply R.
Thus either P is true or Q is true; though not both
(perhaps neither is true).
terms of the interactions of beliefs in the web, we may be led to
reject or deny Q
instead of P in order to achieve an overall equilibrium within
the whole system. The point is that although experience inspired us
to reject R, it didn't (directly) inspire us to the rejection
of the conjunction, P ∧ Q. (Or perhaps it did; though
indirectly.) That is, a direct experience got us to reject R,
and then that same experience does get us to reject the conjunction,
P ∧ Q, in that without it we wouldn't have rejected
the conjunction. We can say, then, that experience only indirectly
got us to reject the conjunction P∧ Q.
of BonJour’s main targets is the idea that Quinean ‘systems’ or
“the web of belief” somehow escapes from the a priori.
Such a web or system is holistic in nature and is only supposed to
“touch experience at the edges”. BonJour firstly describes the
Duhemian thesis from which Quine derived his holistic position.
extreme version of this thesis is the holistic claim that nothing
less than ‘the whole of science’ can be meaningfully confronted
with experience.” (ibid., p. 104/5)
because of the holistic nature of the entire system that even “a
priori reasons” (or “our cherished logical laws”) may be
given up if they don't concur or cohere with the whole system. Thus
this he infers that any claim in the total ‘web of belief’,
including those for which there are allegedly a priori reasons, might
be ‘given up’ in order to accommodate ‘recalcitrant
experience’, and so, apparently, that sucha priori reasons do not exist after
all.”(ibid., pp. 104/5)
interesting thing about this quote is that BonJour himself believes
that some a priori reasons (or beliefs) may or can be “given
up” due to new experiences. So why not all of them? The point is,
however, that they can indeed be given up; though still be a
priori in nature (as we shall see in a moment).
first point that BonJour makes about Quine’s position above is that
it “begs the question” against the a priori in that
there's a simple assumption that, when it comes to the web of belief,
experience (whether ‘recalcitrant’ or not) is everything. BonJour
is claiming that the Quinean web of belief must contain a priori
links between the individual beliefs contained in the web. However,
BonJour is keen to stress that
rationalist can freely admit that holistic empirical reasons of this
sort may count against a claim for which there is an
a priori reason (or the reverse),
with the ultimate outcome depending on their relative weight in a
particular case”.(ibid., pp. 104/5)
this mean that BonJour believes that an “a priori reason”
(which has “holistic empirical reasons” which “count against”
it) must not thereby be a genuine a priori reason? Or does
BonJour believe that a reason can indeed be a priori and still
have holistic reasons which count against it?
that acknowledgement of the corrigibility of a priori reasons,
BonJour says that the rationalist will still “also insist that the
very connections among beliefs that result in the holistic web can
only be understood as a priori in character” (ibid., pp. 104-5).
state two moves here which he believes must be a priori in
nature. First, take the ‘conditional’:
If a claim satisfies all of the conditions thus specified
Then it's likely to be true.
the move from P to Q can't be empirical in nature nor
based on experience. Thus the inference, according to BonJour, must
be a priori. Not only that: BonJour questions the truth of the
conditional by asking: “[W]hat reason there is for thinking that
this conditional proposition is itself true?” (ibid., p. 105) In
other words, our earlier conditional, if P, then Q, is “not
directly justified by experience” (ibid., p. 105). Thus can it be
included in a system of belief which is based around the importance
of the outer beliefs and their direct relations to experience?
BonJour thinks that it shouldn't be because an “appeal to its
inclusion in such a system of belief would be plainly circular”
(ibid., p. 105). BonJour’s general conclusion to this is that
idea of an a priori reason is both indispensable for any
justification beyond that yielded by direct experience and at least
as well understood as the idea of holistic empirical justification,
which turns out in fact to depend upon it”.(ibid., p. 105)
then puts a point which was once expressed by Donald Davidson:
another belief can justify a belief, not experience itself.”
this we can say that experience, in and of itself, never justifies a
belief. It may follow from this that a priori logical
connections to previous beliefs and reasons provide us with the
complete picture of justification. It's this very link between one
belief (close to experience or not) and another that BonJour fixes
upon. He writes that
can provide a good reason for thinking that a belief in this category
is true only if we have a logically prior good reason”. (ibid.,
an experiential belief can only be deemed true if it has an a
priori link with a “logically priori good reason” (ibid., p.
102) or with other beliefs (as Davidson puts it). That link won't be
empirical or experiential in nature.
Michael Devitt’s “Quinean alternative” we have the following
two-fold web. It includes:
Beliefs which are ‘close to experience’ (on the ‘periphery’
of the Quinean web).
Beliefs that are in the interior of the web.
to the Quinean picture, beliefs captured by 2) above are justified
“via links with beliefs at the periphery” (2008: Devitt, p. 2).
There's a link between interior beliefs and the peripheral beliefs
which are “close to experience”. Though, as many aprioristic
logicians and philosophers point out, what about these links
themselves? That is, “these justifications depend on the links
themselves being justified” (ibid., p. 2). These links must be
logical. And if they're logical, then they must be a priori in
nature. Thus even Quine’s web has an a priori element. Or so
the story goes.
has more to say about the links in Quine’s web of belief (or the
links in any such system). He writes (quoted in Devitt, 2008):
there is no a priori insight…
no prediction will follow any more than any other… any… sort of
connection between the parts of the system will become essentially
arbitrary.”(2008: Devitt, p. 3)
is simply saying that if you don't accept a priori justification
(or ‘insight’) for the links in Quine’s web of belief (or any
other corresponding system), then the “connection between the parts
of the system will become essentially arbitrary”. This must mean
that if we don't have a priori justification (or insight),
then we effectively have nothing (in such systems). And if we have
nothing, then that is bound to lead to the “arbitrary” nature of
the “connections between the parts of the system”.
question remains: Is the a priori way out the only way out?
we accept BonJour’s prognosis of the rejection of the a priori
vis-à-vis Quine’s web of belief (or any other such parallel
system), then it's no surprise the BonJour thinks “the rejection of
all a priori justification is tantamount to intellectual suicide”
(ibid., p. 3).
question is again: Is the a priori the only game in town?
mentioned that most people see logic as perhaps the only domain of
the a priori (along with mathematics). Devitt says that
objection is that logic must be seen asa
priori because we need logic to get
evidence for against anything”. (ibid., p. 3)
is saying that, yes, fair enough, evidence is of supreme importance
in science and in just about every other disciple. However, without
the framework of logic, all this evidence would amount to nothing.
Indeed it wouldn't even be evidence “for or against anything” if
it were not for this logical framework or the logical links between
this beliefs and that belief, or between this bit of evidence and
that bit of evidence. Logic ties the whole thing together. That is
why people say that “the logic of science” isn't itself
scientific or a science. Science, as well as naturalism or
empiricism, require logic. Thus science and empiricism (or
naturalism) also require the a priori.