Discrimination and Perceptual Knowledge

There are three central notions to this paper. First, Alvin adopts reliability as the common basis for why various cognitive mechanisms produce knowledge. Second, he attempts to understand reliability in the context of the reliable ability to discriminate states of affairs. Finally, he tries to understand the sort of discrimination necessary for knowledge in terms of discrimination between relevant alternatives.

Reliability

"...a cognitive mechanism is reliable if it not only produces true beliefs in actual situations, but would produce true beliefs, or at least inhibits false beliefs, in relevant counterfactual situations." (p.163)

So, reliability is thought of a counterfactual property of a process or mechanism such that it produces true beliefs far in excess of false beliefs.

Discrimination, Alternatives, and Barns

The Barn Example

Failure to Discriminate Between Relevant Alternatives

Alternatives and Scepticism

Relevance

Two Possible Answers:

-Context Exhaustively Determines Relevance

-Semantic Indeterminacy/Psychological Regularity

-Speaker Presupposition

-Sentences of the form 'S knows that p' express vague or

indeterminate propositions.

Trudy and Judy

First Pass Analysis

S ( noninferentially ) perceptually knows that p if and only if

(1) S ( noninferentially ) perceptually believes that p,

(2) p is true, and

(3) there is no relevant contrary q of p such that, if q were true (rather than p), then S would (still) believe that p.

Of Dachshunds and Wolves

Perceptual Equivalence

Discrimination and Perceptual Knowledge

Reliability

"...a cognitive mechanism is reliable if it not only produces true beliefs in actual situations, but would produce true beliefs, or at least inhibits false beliefs, in relevant counterfactual situations." (p.163)

Discrimination, Alternatives, and Barns

The Barn Example

Failure to Discriminate Between Relevant Alternatives

Alternatives and Scepticism

Relevance

Two Possible Answers:

-Context Exhaustively Determines Relevance

-Semantic Indeterminacy/Psychological Regularity

-Speaker Presupposition

-Sentences of the form 'S knows that p' express vague or

indeterminate propositions.

Trudy and Judy

First Pass Analysis

S ( noninferentially ) perceptually knows that p if and only if

(1) S ( noninferentially ) perceptually believes that p,

(2) p is true, and

(3) there is no relevant contrary q of p such that, if q were true (rather than p), then S would (still) believe that p.

Of Dachshunds and Wolves

Perceptual Equivalence