The study of knowledge, evidence and rationality
Philosophical Skepticism: Denies that we have much knowledge, or at all and
questions the validity of evidence and judgment.
P1: In order to know something, it must be impossible to be mistaken.
P2: It’s always possible to be mistaken about P (for all a posteriori claims)
C: Hence, one doesn’t know any a posteriori P.
If X is a necessary condition for Y (If Y, then X)
If X is a sufficient condition for Y (If X than Y)
Ex. Studying hard is a necessary condition for getting an A, if I got an A, then I
studied hard, necessarily.
If studying hard is sufficient for getting an A, if I study hard, than I will get an A.
Justified True Belief (JTB): Account for knowledge and also the necessary and
sufficient conditions for knowledge.
S knows that P if and only if
(1) P is true
(2) S believes P
(3) S has evidence for P
(1) and (2) are not sufficient for knowledge.
True beliefs without evidence are NOT knowledge.
Lucky guesses do not count as knowledge*.
Gettier: argues that all (1), (2) and (3) are not sufficient for knowledge and
comes up with his own counter example for JTB.
Smith works in an office and has a generally reliable boss named Jones. One
day, Jones comes into the office and says, “Mary will get the promotion” Smith believes:
a) Mary will get the promotion,
Smith also discovers that Mar