  In addition to this radical kind of empiricism, the PAO continues to uphold the broadly Kantian view that cognition is necessarily limited, or, as Vaihinger sometimes puts it, that there is no “identity between thought and being.” However, it is no longer limited in the sense of being cut off from some transcendent realm of things in themselves, but in being essentially incomplete. The point is best appreciated by attending to another distinction central to the PAO—that between fictions and hypotheses. Hypotheses (not to be confused with so-called “hypothetical judgments”) are judgments that are “problematic” in form, i.e., which have the form ‘it is possible that A is B’ (where the relevant sense of possibility is epistemic). Thus, if the judgment ‘matter is composed of atoms’ is a hypothesis, the person making it is maintaining that it may be true, and holds out hope that it may be confirmed or falsified in the future. By contrast, and as we have seen already, the fictive judgment has the form ‘A is to be regarded as if it were B (when in fact A is not B).’ Since Vaihinger holds that such judgments can be licensed by their practical utility, and because it is our practical aims that ultimately guide and constrain theoretical inquiry, Vaihinger infers that every theory will necessarily involve some fictions; not even the best theory will consist entirely of hypotheses, much less true hypotheses.