The term modal interpretation is ambiguous. It is a proper name that refers to a number of particular interpretations of quantum mechanics. And it is a term that singles out a class of conceptually similar interpretations, which includes proposals that are not generally referred to as modal ones.

This ambiguity was already present when Bas C. van Fraassen coined the term in the 1970s by transposing the semantic analysis of modal logics to quantum logic. The resulting modal interpretation of quantum logic defined a class of interpretations of quantum mechanics, of which van Fraassen developed one instance in detail, called the Copenhagen modal interpretation. In the 1980s Simon Kochen and Dennis Dieks developed independently an interpretation of quantum mechanics that became known as the modal interpretation, turning the term into a proper name. In the 1990s further research produced new...