 The second category is his theory of mental content. Following Donald Davidson in broad outlines, Lewis held that the contents of a person’s mental states are those contents that ’fit’ the typical causal profile of the state. For example, a state isn’t constituted by the combination of a desire for some end plus a belief that waving will bring about that end, unless it typically causes waving. In this respect Lewis’s views resembled  interpretationist  theories of beliefs. But he differed from other interpretationists in several ways. We will focus here on two of them. Lewis held that mental contents are typically properties, not propositions. And he held that a theory of mental content requires an inegalitarian theory of properties. We’ll look at his theory of content in sections 4.4–4.6.