Abstract

Bredo C. Johnsen1 misconceives my strictures concerning acceptance of the following principle : If A both knows that p and knows that p entails q, then A can come to know that q.Johnsen seems unaware that my criticism was intended to apply only after is made to appear in its most plausible light; that is, only after its consequent is interpreted as: ’It is logically possible for A to know that q.’ Without this interpretation might be dismissed simply on the grounds that A suffers from some physical or psychological disability that prevents him from drawing inferences from what he knows.Properly interpreted, remains acceptable as long as the propositions substituted for p and q are such that it is at least logically possible for A to get evidence enough to make them known. Agreement on this point is itself enough to render Johnsen's own examples irrelevant. For instance, even though it may be physically impossible for A to get adequate evidence that in the constellation Andromeda there is a planet intermediate in size between Venus and Earth, the foregoing is still a fit substitution instance for q; but since such a q does not suffice to falsify the consequent of, it does nothing to generate any skeptical argument, either.