KANT'S A PRIORI
According
to Kant, what knowledge is analytic a priori?
According
to Kant, what knowledge is synthetic a priori?
(1)
All bodies are extended.
(2)
All bodies have weight.
(3)
Gold is a yellow metal.
(4)
7 +5 = 12.
(5)
A straight line is the shortest path between two points.
(6)
All substance is permanent (compare: Law
of Conservation of Matter or Law of Conservation of Energy).
(7)
F = ma.
(8)
Every effect has a cause.
(9)
Every event has a cause.
(10)
Principle of Sufficient Reason
(11)
Pure mathematics (includes Euclidean geometry)
(12)
Pure physics (includes
(13)
Law of Excluded Middle
(14)
Law of Non-Contradiction
Kant's
Formula for the Synthetic A Priori: Propositions that must be confirmed by all possible
experience. No experience could
disconfirm them.
Recalcitrant
data from the history of science:
Replacement of Newtonian physics and Euclidean geometry by Relativity
Theory (with a non-Euclidean geometry) and quantum mechanics (with probabilistic
rather than strictly causal relations).
QUINE'S ARGUMENTS AGAINST
ANALYTICITY
(1)
What are the two dogmas?
(2)
Why does Quine think that they are at root the same?
(3)
Why does Quine think that there are no statements
that are confirmed no matter what?
Holistic
confirmation and disconfirmation
Radical revisability.
QUINE'S EXAMPLES
(1) No unmarried man is
married.
(2) No bachelor is
married.
Tests: Interchangeability salva
veritate.
Correct the text (395):
(3) All and only bachelors
are unmarried men
is analytic.
(4) Necessarily all and only
bachelors are bachelors.
(5) Necessarily all and only
bachelors are unmarried men.
The "closed curve in
space"(395): analytic, a priori,
necessary, true by definition or in virtue of meaning.
Are there any exceptions?
What about the Pope?
Example of "creature
with a heart" and "creature with kidneys"
Is "Everything that is
green is extended" analytic?
BONJOUR'S DEFENSE OF A
PRIORI JUSTIFICATION
I. Two Roles for A
Priori Insight
1.
Source of premises
2.
Validate steps of reasoning.
Examples
of propositions justified a priori according to BonJour:
1. All bachelors are unmarried.
2. Nothing can be red and green all over at the
same time.
3. Nothing can be red and blue all over at the
same time.
4. If A is taller than B and B is taller than C,
then A is taller than C. (Transitivity
of "taller than")
5. There are no round squares.
6. 2 + 3 = 5 (Compare 2+2 = 4 with 25
– 5 = 33).
7. A cube has 12 edges.
8. Logical example: Inference that David ate the last piece of
cake (105).
9. Law of Non-Contradiction
10. Philosophy is a priori (106).
Example
of reasoning justified a priori according to BonJour:
Premises:
Either
David ate the last piece of cake or else Jennifer ate it.
Jennifer
did not eat the last piece of cake (perhaps because she was at work for the
entire time in question).
Conclusion: David ate the last piece of cake.
II. Skepticism about
All A Priori Justification = Intellectual Suicide
Why does BonJour
believe this?
III. Skepticism about
Synthetic A Priori Justification
What is BonJour's
Reply?
BonJour's "Companions in
Guilt" Defense of Synthetic A Priori
Justification
The
Inadequacy of Accounts of Analyticity
(a)
Conditional Accounts
(i) Kantian and Fregean
(ii) also Kant's
alternative formulation
(b)
No Epistemological Insight
(i) Lewis
(ii) Salmon: "empty of factual
content"
(iii) true by
virtue of meaning
(c) Too Obscure or Too Implausible
(i)
true by convention
(ii) implicit
definitions
IV. BonJour's
Moderate Rationalism
1.
Intuitive apprehension of necessary truth (rational insight or rational
intuition)
2.
Fallibility (apparent rational insight or apparent self-evidence)
3.
An Externalist Requirement: the
condition of cognitive sanity and putative rational insights.
The Fallibility Problem for
Epistemology and for Philosophy Generally
What
Do BonJour and Quine Agree
On?
(1) No important difference between analytic a
priori and synthetic a priori.
(2)
If there is a priori justification, it is not infallible.
Is
there a priori justification?
V. Issues Raised by BonJour's
Account:
1.
What is the difference between a putative, an apparent, and a genuine rational
insight?
[Why is BonJour
an externalist about both apparent and genuine a priori insight?]
2.
How can a mistaken rational insight be corrected?
[Are all mistakes internally correctable?]
3. Does
reasoning require direct rational insight?
[What is the content of the insight?]
4. Can any
substantive position in philosophy be justified purely a priori—that is,
by direct rational insight of premises and deductive reasoning from such
premises?
[Isn't it relevant whether other people agree or
disagree?]
Stich's Challenge
Could
human reasoning not be based on a priori insight into valid principles
of inference?
I. The evidence that people do not reason in
accordance with valid principles:
1. Wason Selection Task:
Deductively invalid reasoning.
2.
Inconsistencies in probabilistic reasoning.
3.
Belief perseverance and debriefing.
Conditional: If there is a vowel on one side, there is an
even number on the other.
|
|
E |
|
4 |
|
5 |
|
C |
|
a b
c d
Conditional: If a patron is drinking beer, s/he is 21 of
older.
|
|
Beer |
|
23 |
|
18 |
|
Coke |
|
a b
c d
"If p then q" is
equivalent to "‑(p&-q)"
Test for this: -(Beer & under
21)
In the first example, the
test would be:
-(Vowel & odd number). Why don't people see this?
5. Assume that the probability of a woman giving
birth to a boy is the same as the probability of a woman giving birth to a girl
(1/2 in both cases). In families with
two children of which at least one is a girl, what is the probability that the
other child is also a girl?
In families with two
children, what is the probability that the first child is a girl? a boy?
In families with two children,
what is the probability that the second child is a girl? a
boy?
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GG: prob = 1/4
G These
three
GB: prob = 1/4 outcomes are
equally probable.
BG: prob = 1/4
B
BB: prob = 1/4
More
evidence: False Proofs of Fermat's Last
Theorem:
“In 1908, the Wolfskehl
Prize of one hundred thousand marks was offered in
II. Who sets the
standards for Stich? Experts.
III. How reliable are
the experts? The Monty
Hall Problem.
IV. Could good
reasoning be a combination of useful heuristics that has been selected for by
biological and cultural evolution rather than something that requires insight
into necessary truths? What is the status of deductive logic on this
account?
V. How would BonJour
reply?