Metaphysical Categories
Necessary Truth/Contingent
Truth
Epistemological Categories (Categories
of Justification or Knowledge)
A Priori/A
Posteriori
A Priori Justification is defined both negatively and
positively
Negative:
justification independent of experience
Positive: direct
rational insight into necessary truth.
Semantic Categories (Categories
of Proposition)
Analytic/Synthetic
Kant's account:
Subject contains the predicate.
Fregean account: Reducible to logic and definitions.
Semantic account: True
in virtue of meaning.
What did Kant classify as
analytic a priori?
What did Kant classify as
synthetic a priori?
Challenges to A Priori
Justification
Quine's arguments against
analyticity are really arguments against all a priori justification.
Quine's Coherentist
Challenge: Examples from physics (F=ma),
geometry (parallels postulate), logic (Law of the Excluded Middle), and
epistemology (traditional definition of knowledge).
Nozick's Naturalist's
Challenge: Evolution has produced
powerful intuitions because they work well in this world. No need for rational insight into necessary
truth.
Examples: Objects fall
down if not supported. Heavier objects
fall faster than lighter ones.
BonJour's
Fallibilist Foundationalist
Defense of Rationalism (i.e., a priori justification)
Objections
to the three conceptions of analyticity. What is the basic objection?
Is BonJour
a foundationalist about a priori justification?
Are the foundations infallible[WJT1] ? The distinction between
apparent and genuine a priori insight.
The Two-Part Role of A Priori Justification in Reasoning:
(1) Premises
(2) Inferential connections
Why does BonJour
think that the second role is more important?
[Hint: Why does he think it makes
a priori justification indispensable?]
The Epistemic Indispensability of A
Priori Justification for Reasoning
Let O be all of our empirical
beliefs that can be justified by direct observation.
Let P be any other contingent
proposition that we take ourselves to be justified in believing.
Consider the
conditional: If O then P.
We are not justified in
believing that P unless we are justified in believing O and justified in
believing that if O then P.
What could be the
justification for believing that conditional?
It cannot be directly justified by observation. If it is justified at all, it must be
justified a priori.
CONCLUSION: We cannot be justified in believing that P
unless we have some a priori justification.
Questions: Why does reasoning have to involve any
beliefs about the premises and the conclusion?
Why can't we just infer P from O without any beliefs about the
conditional at all? How would a
naturalist such as Nozick reply to BonJour?
The Problem of (Justifying) Induction
What is the problem of induction[WJT2] ?
(1) Observationally
determinable features
(2) Standard inductive
premise (concerning past observations)
(3) Standard inductive
conclusion (concerning future observations
An Induction
(1) Observationally determinable
features: "Crow" and
"black" can be determined by observation.
(2) Standard inductive
premise: All observed crows have been
black.
(3) Standard inductive
conclusion: All crows observed in the
future will be black.
Hume's Dilemma
Hume's Dilemma: (1) Either induction
can be justified by demonstrative reasoning or by experimental reasoning.
(2) It cannot be justified by
demonstrative reasoning (Why not?)
(3) Any experimental
justification would be viciously circular (Why?)
Conclusion: There is no justification of induction.
Potential Defenses of Induction
(1) Pragmatic Vindication
(2) Ordinary Language
Justification
(3) A Priori Justification
According to BonJour, what would an
a priori justification of induction look like?
A fourth alternative added by
Talbott: Non-separable cognitive
processes: Processes whose reliability
cannot be assessed without employing those very processes. Induction may be a non-separable cognitive
process. What others are there?
Hume would say that determinations
of the reliability of non-separable cognitive processes are viciously circular. Are they?
To be continued.