ABSTRACT
INTENSIONALITY IN PHILOSOPHY AND METAMATHEMATICS
Truth and reference (i.e., extensions) on the one side and meaning (i.e., intensions) on the other side are closely related: for example, principles like every true sentence is meaningful and expressions with the same meaning refer to the same things (if they refer) seem to be correct from an intuitive point of view. Of course, this does not mean that, e.g., truth or falsity are the meanings of (declarative) sentences. Nonetheless, were it not because of contexts taken from ordinary language — like those containing modalities and propositional attitudes — expressions like “meaning” could perhaps be explained by employing terminology taken solely from referential semantics. Thus, it has been claimed that for scientific purposes one may well get on with purely extensional languages.1 In fact, this seems to be “obviously” true for the mathematical discourse.
