In this essay, I discuss some of the important logical principles governing the concepts of knowledge, certainty and probability. In the first section, I suggest a series of definitions of epistemic terms, employing as primitive the locution ?p is epistemi?cally possible to S? In the second section, I develop an epistemic concept of probability and compare it to the concepts of certainty and knowledge. In the third section, I relate the epistemic concepts of certainty and probability to the quantifiers of (...) traditional logic and to a non?episteznic concept of probability. I conclude by noting similarities and differences between the two concepts of probability. (shrink)

This paper deals with the problem of vindicating a particular type of inductive rule, a rule to govern inferences from observed frequencies to limits of relative frequencies. Reichenbach's rule of induction is defended. By application of two conditions, normalizing conditions and a criterion of linguistic invariance, it is argued that alternative rules lead to contradiction. It is then argued that the rule of induction does not lead to contradiction when suitable restrictions are placed upon the predicates admitted. Goodman's grue-bleen paradox (...) is considered, and an attempt to resolve it is offered. Finally, Reichenbach's pragmatic argument, hinging on convergence properties, is applied. (shrink)