In this paper I focus on Cassirer’s functionalist theory of truth in order to argue that the Positivistic theory of knowledge fails to explain how it is that physics provides us with truth-evaluable and reliably objective descriptions of the world. This argument is based on Cassirer’s idea that what the Positivistic theory of knowledge normally considers as the “factual” of physics is, in fact, unachievable and falsely conceived. I show that Cassirer’s focus on how measurement is made possible, as well (...) as how technological instruments are put to use in physical research, enables him to offer an alternative account of truth, i.e., a functionalist theory of truth, which is philosophically attractive and rationally plausible. (shrink)