Many phrases have been used to express what are sometimes called anti-realist conceptions of truth: ‘verifiability’, ‘knowability’, ‘rational acceptability’, ‘warranted assertability’. In spite of their obvious differences, all four of these phrases have a common form; each is a cognitive attitude modified by ‘-ability’. They speak of the possibility of verification, knowledge, rational acceptance or warranted assertion. Schematically, it seems to be claimed that it is true that A if and only if it is possible that it is E'd that A, where ‘E’ is to be replaced by some cognitive verb and ‘A’ by any indicative sentence of the class to which the anti-realist conception is being claimed to apply. Since truth is redundant as a sentential operator, this boils down to the following thesis, where ‘p’ is a propositional variable and ‘M’ expresses the appropriate kind of possibility:
(*) also formalizes views such as Putnam's: ‘To claim a statement is true is to claim it could be justified’ [11, p. 56]. It is no doubt a crude model for anti-realism, but one has to start somewhere; by seeing how and why more sophisticated versions of anti-realism differ from (*) one should be able to understand them better too. Moreover, if an anti-realist rejects the equation of truth with, say, warranted assertibility, arguing that truth is rather to be identified with the possibility of getting into a position in which one's warrant to assert somehow cannot be overturned, the form of (*) is preserved, for truth is still being identified with the possibility of something.