No new reading for Tuesday.

1

• No new reading for Tuesday.
• Next Thursdays reading response should address
  Georges Reys Resisting Normativism in
  Psychology (Chapter 5)

2
The McKinsey Problem

• 1. I can know a priori the contents of my
  beliefs, for example, my belief that water is
  wet.
• 2. My thinking that water is wet conceptually
  implies that H2O exists. (This is entailed by
  externalism, so long as we take for granted what
  we think we know now about chemistry.)
• 3. That H2O exists can be known only a posteriori.

3

• Whats the problem?
• If I know that Im thinking that water is wet,
  and I know a priori that externalism is true,
  then I should be able to know a priori that H2O
  exists (whether one appeals to CAK or CA).
• This contradicts (3). At least one of the 3
  claims must be rejected.

4
Brueckners Solution

• Externalism does not entail that (2) can be known
  a priori even if we can know a priori that
  externalism is true, this does not yield a priori
  knowledge of the specific external conditions
  necessary for us to have thoughts with the
  relevant contents.
• Its merely metaphysically necessary that H2O
  exists if Im thinking that water is wet (AND if
  water is, in fact, H2O) its not conceptually
  entailed by my being in that state alone, even if
  we know externalism a priori.

5
A Posteriori Necessity

• Semantic externalists are widely taken to have
  shown that some necessary truths are (or can be,
  relative to our powers?) known only a posteriori.
• Water is H2O is necessarily true, because it
  expresses the same proposition as H2O is H2O,
  which couldnt possibly be false. But we had to
  do empirical work to figure out that the stuff we
  were talking about is H2O.

6
CAK and CA (p. 42)

• CAK requires that you know the relevant
  conditional a priori, in order to derive the
  thereby a priori known consequent from the a
  priori known antecedent.
• CA requires only that a logical deduction can get
  you from the a priori known antecedent to the
  consequent (which is thereby known a priori).

7

• The gap between CAK and CA is important because
  we might be thinking about metaphysical necessity
  that cant be known a priori.
• Think about the difference between Larry and
  Pegasus or between water and phlogiston.

8

• What can a semantic externalist known a priori,
  with regard to (2)?
• If E can be known a priori, it would be something
  like
• if Im thinking that water is wet, then if
  water refers then the stuff it refers to
  exists

9
Basic Concepts

• Alternative response to the McKinsey problem
  some of our concepts the basic ones are such
  that merely having them guarantees that they
  refer to something in the world.
• If so, then if we know which ones these are, then
  knowing the content of our own mental states that
  involve these concepts might well give us a
  priori knowledge of the world, making (3) false,
  but acceptably so.

10
Empty Concepts

• But only if we know a priori which of our
  concepts are basic.
• Even if we know which concepts are basic, the set
  of basic concepts might not include some of the
  concepts involved in mental states to the content
  of which we think we have introspective access
  water, for example.

11

• According to Brueckner, this provides one more
  reason for thinking that there is no statement E
  comprised of a conditional one can know a priori
  (by being conceptually derived from
  anti-individualism).
• At the same time, however, Brueckners reasoning
  might simply give the externalist reason to
  reject (1) (instead of focusing so much on (2)).