Week 2: Skepticism

JTB Theory

A theory of knowledge stating that S knows that P if and only if S believes that P, P is true, and S is justified in believing P.

Evidentialist View

Beliefs are justified for S at time t if and only if S’s total evidence at t supports P.

Total Evidence

All evidence in such a way that there is no epistemic defeater to your belief.

Basing Relation Condition

The belief must be based on specific evidence which directly justifies the belief.

Skepticism about DK

The position that none of our beliefs about D constitute knowledge (where “D” refers to domain of inquiry).

Skepticism about DJ

The position that none of our beliefs about D are justified.

Closure Principle

The principle that if S knows that P entails Q and S knows that P, then S also knows that Q.

Moorean Shift (The Moore Shift)

The claim that it is more rationally justified to believe in certain things (like having hands) than in skeptical scenarios (like being a BIV).

Formal BIV argument via the closure principle

BIV argument goes like this:

1. If you have hands, then you are not a BIV. 

2. You only know that you have hands if you know you are not in a handless BIV. 

3. However, you do not know you are not in a handless BIV.

4. Therefore, you do not know that you have hands. 

It generalises the argument into all knowledge about the external world (contingent truths).