A theory of information is developed in which the informational content of a signal (structure, event) can be specified. This content is expressed by a sentence describing the condition at a source on which the properties of a signal depend in some lawful way. Information, as so defined, though perfectly objective, has the kind of semantic property (intentionality) that seems to be needed for an analysis of cognition. Perceptual knowledge is an information-dependent internal state with a content corresponding to the (...) information producing it. This picture of knowledge captures most of what makes knowledge an important cpistcmological notion. It also avoids many of the problems infecting traditional justificational accounts of knowledge (knowledge as [justified, true belief those (unlike knowledge) having a content that can be either true or false (e.g., belief) – are described in terms of the way internal (presumably neural) structures acquire during learning a certain information-carrying role. The content of these structures (whether true or false) is identified with the kind of information they were developed to carry. (shrink)

According to Fred Dretske's externalist theory of knowledge a subject knows that p if and only if she believes that p and this belief is caused or causally sustained by the information that p. Another famous feature of Dretske's epistemology is his denial that knowledge is closed under known entailment. I argue that, given Dretske's construal of information, he is in fact committed to the view that both information and knowledge are closed under known entailment. Hence, if it is true (...) that, as Dretske also believes, accepting closure leads to skepticism, he must either embrace skepticism or abandon his information theory of knowledge. (shrink)

Externalism about knowledge commits one to a modest form of contextualism: whether one knows depends (or may depend) on circumstances (context) of which one has no knowledge. Such modest contextualism requires the rejection of the KK Principle (If S knows that P, then S knows that S knows that P) - something most people would want to reject anyway - but it does not require (though it is compatible with) a rejection of closure. Radical contextualism, on the other hand, goes (...) a step farther and relativizes knowledge not just to the circumstances of the knower, but to the circumstances of the person attributing knowledge. I reject this more radical form of contextualism and suggest that it confuses (or that it can, at least, be avoided by carefully distinguishing) the relativity in what S is said to know from the relativity in whether S knows what S is said to know. (shrink)