Every case of knowing that S is, was or will be P involves, when analysed, some decision or the acceptance of some decision. This applies equally when you are discussing the so-called tautological propositions of logic and pure mathematics; for you can only claim to “know” that some logical or mathematical proposition is true because you have previously decided to accept that certain meanings shall be attached to certain words, or that certain symbols shall function in a certain way. When we examine what philosophers are doing who demand that we prefix “we know” to this or that part of their analyses of perceptual situations, we find that they are often using “know” in a question-begging manner in order to buttress some particular, and usually contentious, analysis. Nor is any philosopher in a position to lay down rigid and precise rules for the proper use of “know” in ordinary conversation; although he can usefully debate the nature and cogency of the grounds on which decisions, issuing in “know”-statements, are generally made. Lastly, Austin is quite right in claiming that when I say “I know” I give my authority and pledge my word, which I do not do when I merely say “I believe”; but I give my authority and pledge my word only because I have decided, or accepted a decision, that so and so is the case.