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 NonContradiction
Kant's
Formula for the Synthetic A Priori:
Propositions that must be confirmed by all possible experience. No experience could disconfirm them.
Quine will point to recalcitrant data from the history of science:
Replacement
of Newtonian physics and Euclidean geometry by Relativity Theory (with a
nonEuclidean geometry) and quantum mechanics (with probabilistic rather than
strictly causal relations).
QUINE'S ARGUMENTS AGAINST
ANALYTICITY (REALLY AN ARGUMENT AGAINST THE A PRIORI)
(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?
HOW THE TWO DOGMAS ARE
RELATED
The
verificationist picture: Each sentence’s meaning can be given by an
ordered pair of:
<confirmation (verification) conditions, infirmation
(disconfirmation) conditions>.
When
all possible experience counts as a confirmation condition and no possible
experience is an infirmation condition, the sentence
is analytic.
This
assumes that individual sentences have confirmation and information
conditions. This is called meaning atomism.
Quine’s Holist Alternative:
THE WEB OF BELIEF
Confirmation
and disconfirmation are holistic, not atomistic.
Radical revisability.
The examples of Euclidean geometry and Newtonian physics.
For
Quine, even the laws of logic are in principle
revisable.
This
is called meaning holism.
QUINE'S EXAMPLES
(1) No unmarried man is
married.
(2) No bachelor is
married.
Correct the text (395):
(3) All and only bachelors
are unmarried men.
(3) 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?
Consider Kant’s list again.
For Quine,
there is only one kind of epistemic justification. It is holistic and empirical.
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 2^{5}
– 5 = 3^{3}).
7. A cube has 12 edges.
8. Logical example: Inference that David ate the last piece of
cake (105).
9. Law of NonContradiction
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 selfevidence)
3.
Externalist Requirements: (1) the
condition of cognitive sanity; (2) conditions for apparent rational insights;
(3) reliability of memory. (There are
actually other externalist conditions in BonJour’s
account.)
The Fallibility Problem for
Epistemology and for Philosophy Generally
What
Do BonJour and Quine Agree
On?
(1) Less important agreement: No important difference between analytic a
priori and synthetic a priori.
(2)
Most important agreement: 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?]
5. Can the
rational degree of belief in a putative a
priori insight itself be determined purely a priori? [What led BonJour to become a fallibilist about apparent a priori insight?]
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?
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?
(1)
Not individuals.
(2)
Not majorities.
(3)
Reflective equilibrium of 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?
The Monty Hall Problem
Setup: 3 doors. There are goats behind two of them
and a car behind one. You want the car,
not a goat.
Key claim: No matter which door you pick, the host can AND
WILL always open a door with a goat.
Two Strategies:
(1) Stay = Pick a door and
stay (don’t switch) after the host opens a door. What is the expected percentage of wins with
this strategy?
(2) Switch = Pick a door and
switch to the unopened door after the host opens a door. What is the expected percentage of wins with
this strategy?
In this case, powerful
apparent a priori intuitions prevent
learning.
Pigeons and the Monty Hall Problem
(Herbranson and Schroeder
2010).
Comparison of six pigeons and
13 undergrads:
On the first day, the pigeons
STAYED 2/3 of the time and SWITCHED only onethird of the time, which indicates
that they did not have any a priori
intuitions about the situation. By day
30, the pigeons SWITCHED more than 96% of the time. The pigeons had effectively learned to
SWITCH, with some random checking for changes in the payoff to the other
strategy.
On the first day, the
undergraduates SWITCHED slightly more often than they STAYED, which is
compatible with the hypothesis that they did not think that any strategy had
any advantage over the other. By day 30,
the human subjects SWITCHED 2/3 of the time, but they did not seem to be
increasing from that level.
Which species is more
sensitive to the pattern of payoffs (experience)?