The articles and essays in this website range from off-the-cuff blogs to worked-out pieces. They also range from the short to the long. Many of these pieces are introductory (i.e., educational) in nature; though, even when introductory, they still include additional commentary. Older material (dating back mainly to 2005) is being added to this blog over time.
Sunday, 19 July 2015
Michael Devitt: What is the a Priori?
many defences of positions in philosophy, the defence of the a
priori is often negative in nature. Such defences are like the
proposition is not a sentence or a statement.”
we also often get:
What is the nature of a priori knowledge?
It is knowledge which isn't derived from experience.
is a little like the following:
What is a dog?
A dog isn't a cat.
least experiential knowledge and a priori knowledge are both
seen as examples of knowledge. So the cat and the dog example is
not fair; though they're both animals and mammals. Clearly a cup of
tea isn't a cat either.
‘knowledge’ isn't derived from experience (in a loose sense). Is
that a priori? Even if it is, it doesn't tell us what the a
priori is: it gives us an example of the a priori. (Just
as we initially defined the a priori in terms of what it
isn't.) This was the problem Quine had with analyticity when
people defined this notion in terms of examples of analyticity
(or in terms of analytic statements).
Michael Devitt wants is a “positive characterisation” of the a
priori. What sort of characterisation of the a priori would
that be? Devitt says that
need to describe a process for justifying a belief that is different
from the empirical way and that we have some reason for thinking is
process of a priori justification is very hard to describe.
Even apriorists (such as Laurence BonJour) admit that. That, of
course, isn't a absolute argument against the a priori. Many
things in philosophy and science are difficult to describe and indeed
sometimes classed as “primitive” or “unanalysable”. However,
it's not just the process of a priori justification that’s
at issue here; but also whether or not it's “actual” (as Devitt
puts it). What reason do we have for believing that the a priori
(or a priori justification) actually exists or is, as it
were, instantiated in minds?
and Their a Priori
all Laurence BonJour’s defences of the a priori are really
arguments. They aren't necessarily either logical or strictly
example, he's written that
rejection of any sort of a priori justification leads
inexorably to a severe scepticism’ and to the undermining of
‘reasoning or argument in general”.
is a warning about the repercussions of rejecting the a priori,
not an argument against those who reject it or an argument in favour
of it. (Perhaps we can call it an example of catastrophising; as some
psychotherapists put it.)
does the rejection of the a priori lead to scepticism? Why
does it lead to the “undermining of reasoning or argument in
sums up BonJour's interesting position as to why this may be the
Devitt’s “Quinian alternative” we have the following two-fold
“web” which includes:
which are “close to experience” (on the “periphery” of the
that are in the interior of the web.
to the Quinian picture, beliefs captured by ii) above are justified
“via links with beliefs at the periphery”. There are links
between interior beliefs and the peripheral beliefs which are “close
to experience”. But as many aprioristic logicians and philosophers
point out, what about those links themselves? That is, “these
justifications depend on the links themselves being justified”.
Thus 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.
clearly, the interior beliefs can't be justified by the exterior - or
peripheral - beliefs if the links between the exterior and the
interior aren't themselves justified. But these links are logical and
must therefore be a priori justified. Thus, again, Quinian
webs of beliefs are polluted (as it were) by the a priori. Or
as BonJour puts it: “the justification of these links has to be a
priori; it could not come from experience”.
strange thing is that many would think that even empiricists or
naturalists would happily accept that anything purely logical must be a
priori in nature. Thus it must follow that these links between
the exterior and interior beliefs must also be a priori
justified. However, Devitt's title is ‘There is no a Priori’.
He must believe that these logical or evidential links mustn't in
fact be a priori (or justified a priori).
has more to say about the links in Quinian web/s of belief (or the
links in any such system). He writes (quoted in Devitt):
if 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.”
is simply saying that if you don't accept a priori justification
(or “insight”) for the links in a Quinian 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”. The question is,
then: Is the a priori way out the only way out? And if we accept
BonJour’s prognosis of the rejection of the a priori
vis-à-vis Quinian webs of belief (or any other such parallel
systems), then it's no surprise the BonJour thinks “the rejection
of all a priori justification is tantamount to intellectual
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 apriori (along with mathematics). Devitt says that
“the objection is that logic must be seen as a priori
because we need logic to get evidence for against anything”.
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 a priori logic, all this evidence would
amount to nothing. Indeed it wouldn't even be evidence “for or
against anything” if it weren't for such logical frameworks. (Or
the logical links between this belief and that belief; or between
this bit of evidence and that bit of evidence.) Logic ties the whole
thing together. That is why philosophers have said that “the logic
of science” isn't itself scientific (or science). Science and even
naturalism (or empiricism) require logic. Thus science and empiricism
(or naturalism) also require the a priori (or a priori
Field is quoted as saying that the
“'links that hold the web of belief together reflect a set of rules
that are part of “an evidential system”’. That is, the links
between beliefs in a system (or wherever) provide a “set of rules”
(which the links must abide by) within what Field calls an
“evidential system”. There would be no system or web without
those links. Therefore, according to BonJour, there would be no
system or web without the a priori.
offers an example of such a ‘link’ or ‘rule’: modus
ponens. We can say that Quinian webs of belief will be full of
examples of the rule modus ponens.
it modus ponens? This:
p then q
the above an example of the a priori in action? Surely it is.
Surely the inference or rule itself instantiates the a priori
and can only be known a priori. Indeed how the corbett does
Devitt argue otherwise? If modus ponens (which is one of the
most common rules or inference patterns) is truly a priori (or
known to be true a priori), then it will be at the very core
of even a Quinian web of belief.
more is said about this relation between a system, S, which is made
up primarily of empirical beliefs or bits of evidence (loosely
described) and its (possibly) a priori “deductive parts”.
Devitt puts his adversary’s position thus:
what about the specific deductive rules that we do have insight into,
rules like modus ponens?
Even if our overall confidence in S is empirical, our confidence in
these deductive parts is a
priori. We know MP
a priori at least.”
is, if the system (S) is largely empirical (or our “confidence in S
is empirical”), then we still need to answer for the specific
deductive rules. It's claimed that we do have (rational) ‘insight’
into them (including into modusponens). We have both
confidence in the empirical parts of the system and a priori
confidence in the deductive parts. The gist of this argument is
that we simply can’t escape from the a priori (at least in
the case of systems like S).
also puts a slightly different slant on all this. Firstly we have the
empirical beliefs (within a system) and their relation to the world
(or to experience).
the evidential or deductive links between the beliefs within that
we can write:
External links involving certain direct causal relations to the
Beliefs which involve inferential relations among thoughts.
Cartesian (or rationalist) stresses both 2b) and 4b) above. Or he even
excludes entirely 1a) and 3a). (Many externalists, perhaps, do the
opposite.) Or, as Devitt puts it, the Cartesian takes only “one of
those relations”. That is,
suppose that, simply in virtue of her [the Cartesian] having that
relation [as in 2b) and 4b)], reflection must lead her to believe
that it does?”.
seems to set up the Cartesian as a straw target; at least at first
glance. In any case, perhaps a philosopher of mind, rather than an
epistemologist, is best suited to comment on these issues.