Distinctions in Distinction

1.Puzzle According to a standard view in contemporary metaphysics, there are no necessary connections between distinct properties. But according to a standard view in philosophy of mind there are necessary connections between distinct properties. In short, we have a puzzle: standard metaphysics inconsistent with standard philosophy of mind. By ‘a standard view in contemporary metaphysics’ I mean, of course, Hume’s dictum that there are no necessary connections between distinct existences. I don’t mean the historical Hume; whether the historical Hume held Hume’s dictum I am sure is a controversial issue, and will not concern us. What will concern us rather is the idea that contemporary metaphysicians such as David Lewis and David Armstrong discuss and attribute to Hume (see, e.g., Lewis 1986 and Armstrong 1997). Of course Hume’s dictum does not say anything explicitly about properties; it talks of existences rather than properties. But ‘existences’ I take it, means ‘things that exist’ and, if we set nominalism aside—as I will do here—properties are things that exist. Hence the Humean dictum entails as a special case that there are no necessary connections between distinct properties. By ‘a standard view in contemporary philosophy of mind’ I mean a view that may itself take a number of forms. One particularly clear version of the view, and the one I will mostly focus on, starts from the claim that psychological properties are