I know something if, and only if, I have some causal contact with the physical world. If I know something, then there is no demon deceiver. I know something. So, I know something just in case both I have causal contact with the physical world and there is no demon deceiver.
-Working backward from the conclusion of this argument, which of the following is the most likely justification of the last step of the derivation?
A) BMP
B) BMT
C) BAssoc
D) BHS
E) Equiv

Question

Quizplus · Accepted Answer

The last step of the derivation uses equivalence (Equiv.), which means that the conclusion "I know something just in case both I have causal contact with the physical world and there is no demon deceiver" is derived by showing that knowing something is equivalent to having causal contact with the physical world and there being no demon deceiver. This is because the argument establishes a bi-conditional relationship between knowing something and the two conditions (causal contact and no demon deceiver), which is what equivalence involves.

I Know Something If, and Only If, I Have Some