As far as I'm concerned, a priori knowledge is stuff hardcoded into
our brains by the genes, and it originates in the gene-pool's
"perception" of the environment over millions of years. The perception
of the environment by a species gene-pool is a very slow, long-term,
and wasteful thing, proceeding on purely Darwinian means. But I
prefer not to believe in knowledge that has no causal origin, and
that's the only causal origin I can appeal to to account for what
philosophers have traditionally referred to as "a priori" knowledge.
Trying to make sense of Kant's abstractions in terms of evolutionary
epistemology is a bit of a struggle, since there's a whole bunch
of jargon from genetic algorithms that describes this stuff
beautifully and doesn't map well to Kant at all. (And furthermore,
my grasp of Kant is dim at best and mostly secondhand.)
Regarding the direct intuitive perception of truth, as with the
perception of the truth of a mathematical theorem after spending
many hours playing with the axioms and lemmas that underlie its
proof, this is still rather mysterious stuff in neuroscientific
terms. Most fruitful work in neuroscience-oriented epistemology
focuses on the origin of empirical knowledge, just as much of Popper
and Lakatos and Bartley's work in critical epistemology focuses on
the origin of mathematical and theoretical knowledge... knowledge
that has "logical structure" that we don't always find in empirical
knowledge. Trying to come up with a model of PCR that works in an
entirely neuroscientific paradigm is a toughie. And I can't quite
get away from the fact that phrases used by the mathematicians to
describe the certainty of mathematical knowledge seems to map nicely
to the vocabulary used by Buddhists and other mystics to describe
the certainties arising in their holistic religious experiences.
Whatever is going on here is going on in some synesthetic area of
the brain that welds together information coming from a variety of
different sensory inputs and postprocessing areas: the mysterious
and ever fruitful "intuition".
Anyway, if you buy into the evolutionary-epistemology metaphor
about a gene-pool being able to "perceive" its environment at a
completely different timescale from that in which we say that an
animal organism can perceive its environment, then I wouldn't
hesitate to identify that "Darwinian perception" as the origin of
the so-called "a priori" knowledge... but the perception of the
gene-pool is not the perception of an individual organism, who is
born with the potential for the development and unfolding of this
"a priori" knowledge but to the pure empiricist is still tabula
rasa as far as a posteriori knowledge is concerned. And clearly
the two interact: a priori "knowledge" serves as a structure within
which a posteriori knowledge can be constructed, but might be a
mere scaffolding that is not much use without being empirically
informed, and actively developed by that other mysterious process
we call "thinking things through".
-- Eric Watt Forste ++ arkuat@pobox.com ++ expectation foils perception -pcd