 But constructed out of which experiences? For the Positivists, the answer seemed obvious: out of the experiential tests that would standardly justify, verify or confirm the claim. Indeed, as Ayer (1934, chap 1) made plain, a significant motivation for the Positivists was to save empirical knowledge from the predations of traditional sceptical arguments about the possibility that all of life is a dream or the deception of an evil demon: if meaning could be tied to verification, such possibilities could be rendered “meaningless” because unverifiable (see Jerry Fodor, 2001, pp. 3–5, for a penetrating discussion of this motivation). In any event, interpreting Wittgenstein’s (1922) Tractatus claims about the nature of language epistemologically along the lines of the American philosopher, C.S. Peirce, they proposed various versions of their “Verifiability Theory of Meaning,” according to which the meaning (or what they called the “cognitive significance”) of any sentence was constituted by the conditions of its empirical  (dis-)confirmation.[5]  Thus, to say that the temperature of a liquid is of a certain magnitude is to say, for example, that the mercury in a thermometer immersed in the liquid would expand to a certain point marked by a numeral representing that magnitude, a claim that would ordinarily be disconfirmed if it didn’t. Closer to “experience”: to say that there is a cat on a mat is just to say that certain patterns of certain familiar visual, tactile and aural appearances are to be expected under certain circumstances.