A Constructive Approach to Intensional Contexts : Remarks on the Metaphysics of Model Theory

The basic distinction between extensional and intensional contexts is one of different denotation conditions (truth conditions). This difference in denotation conditions has been related to a fundamental question of semantic theory, namely: what do expressions of natural 'language denote? Most authors assume that in ex tensional contexts expressions denote 'real objects.' Since the rules of substitutivity of identicals and existential generalization do not hold in intensional contexts (cf. section 1), they are thus forced to postulate that in intensional contexts expressions denote something else. Frege, for example, assumes a de notational ambiguity between 'Bedeutung' and 'Sinn', Russell between 'primary occurrences' and 'secondary occurrences', Quine between 'proper occurrences' and 'accidental occurrences', and Montague between 'extensions' and 'intensions