The empirical skeptic’s claim is that one cannot have knowledge of the external world. The external world is the physical world which one perceives and generally assumes to exist beyond one’s own mind. Cannot is an expression of a conceptual impossibility, since it is neither physically impossible …show more content…
At times, things can seem to be things that they are not. One’s senses can be mislead, leading to a false perceptual belief being held. If all empirical propositions are the result of sensory perception, and sensory perception can be deceived into holding false perceptual beliefs, then should one believe any empirical proposition? In other words, can one know something if it is possible they are wrong about it? Stroud’s responds by asserting that fallibility does not preclude one’s possession of knowledge if it is possible to detect how one’s sensory perception is being misled. If one can identify the conditions under which their sensory perceptions are misleading, then they can use reason and conversation to correct for the errors that would otherwise arise if they uncritically trusted their senses. But what if one cannot detect how their sensory perception is being …show more content…
In which subject S sees a yellow bird B in a tree and asserts that B is a goldfinch. If S knows B is a goldfinch then S must know B is not a canary. S does not know that B is not a canary. Therefore, S does not actually know B is a goldfinch. To justify the necessity of knowing that B is not a canary, Stroud establishes his strong exclusion principle, which states that, “if somebody knows something, p, he must know the falsity of all those things incompatible with his knowing that p”. Upon reflection Stroud realizes the incredibly high bar he is setting regarding the burden of proof necessary for knowledge, so he weakens the principle and establishes the weak exclusion principle in its place, which requires one to know the falsity of all known things incompatible with proposition