J. J. Snodgrass

In contrast to an intensional conception of properties, which says that sameness of intension among properties implies property identity, a hyperintensional conception of properties says that sameness of intension among properties does not imply property identity, and hence distinct properties may have the very same intension. This PhD thesis is about the metaphysical standing of a hyperintensional conception of properties. While this conception of properties might have an important place in discussions concerning the different ways we represent properties in our language and thought, skepticism looms large among proponents of an intensional conception of properties when a metaphysician takes a hyperintensional conception of properties to extend beyond how we represent properties and into discussions concerning how properties themselves are. The central project of this thesis is to articulate the considerations that underlie this skepticism and defend a hyperintensional conception of properties against them. In chapter one, I set the scene by addressing a number of preliminary matters that shape my defence of a hyperintensional conception of properties. In chapter two, I consider and respond to objections that this conception of properties relies on distinct properties that do not have the same intension. In chapter three, I consider and respond to objections that this conception of properties is based upon some linguistic and/or epistemic illusion. In chapter four, I present and examine a modal objection, which calls into question hyperintensional distinctions among properties. In chapter five, I consider and respond to objections that this conception of properties is problematic on theoretical and methodological grounds. In chapter six, I round out my defence by proposing a hyperintensional theory of property identity, in order to resolve two problems that lie at the heart of any metaphysically adequate hyperintensional conception of properties.

Many philosophers believe that identity facts are non-fundamental facts, facts grounded in other facts. In this paper, we discuss what might ground the identity facts for individuals and properties by examining two explanatory identity criteria. One criterion, which we call the Explanatory Leibniz’s Law, is for individuals. The other, which we call the Explanatory Intensional Criterion, is for properties. We argue that, when combined with the widely accepted claim that grounding chains do not contain loops, these two criteria give rise to a contradiction.

Hyperintensionalists like myself hold that there are distinct but co-intensional properties. However, intensionalists object that accepting such properties violates Ockham’s Razor, the principle of parsimony that tells us that things should not be multiplied more than is necessary. After I distinguish between the qualitative parsimony and quantitative parsimony readings of Ockham’s Razor, I present two versions of this objection: the qualitative parsimony objection and the quantitative parsimony objection. I then give a reply to each version that exploits the fact that intensionalists already accept that there are distinct but co-extensional properties. The upshot of this paper is that accepting co-intensional properties does not obviously violate either the qualitative parsimony or quantitative parsimony readings of Ockham’s Razor any more for the hyperintensionalist than accepting only co-extensional properties does for the intensionalist.