Abstract

Idealism is an ontological view, a view about what sorts of things there are in the universe. Idealism holds that what there is depends on our own mental structure and activity. Berkeley of course held that everything was mental; Kant held the more complex view that there was an important distinction between the mental and the physical, but that the structure of the empirical world depended on the activities of minds. Despite radical differences, idealists like Berkeley and Kant share what Ralph Barton Perry called "the cardinal principle of idealism," namely, the principle that "being is dependent on the knowing of it."1 I believe that Hilary Putnam intends his "internal realism" to be a version of idealism in this broad sense; although many of his arguments concern semantic notions like truth and reference, he takes these semantic arguments to have ontological consequences. This is strongly suggested, for instance, by his claim that "'objects' themselves are as much made as discovered, as much products of our conceptual invention as of the 'objective' factor in experience."2 Or again there is this rather Kantian metaphor: "the mind and the world jointly make up the mind and the world."3 But just what is Putnam's ontology?