Michael F. Patton

Adopting temporal parts theory is the most popular way of addressing a host of puzzles about diachronic identity. For example, it is not obvious how I am the same person as the baby who shared my name. With the theory, sameness of person, e.g., consists in being comprised by the same temporally extended, four-dimensional object. However, temporal parts theory has unacceptable consequences for notions of freedom and probability. I show that the only acceptable reading of four-dimensionalism entails that the four dimensional object that is me, say, already exists in its entirety. This entails that all of my future properties are already set. This nearly Spinozistic result robs us of familiar notions of choice and possibility. I argue that these notions are more central to our thinking than temporal parts theory, and that on these grounds we must look elsewhere for solutions to our questions about identity across time.

I consider the answer to the question "Under what conditions do objects add up to or compose something?" Any causal answer falls prey to concerns of vagueness: for any physical relationship R that holds between objects, there will be vague instances of R. These answers will be open to all the problems that accompany any account of vague identity. I reject these causal answers and argue that the right theory of composition must be one of the non-causal theories: Universalism and Nihilism. ;Universalism entails that any two things add up to or compose another thing that has them as parts. Nihilism entails that everything that is spatially coincident composes an object. It should be clear that neither of these theories could suffer from any charge of vagueness, as it cannot be vague whether a thing exists, only whether it stands in some relationship or other to another thing. ;We should accept the theory of Composition that gives us the least metaphysical baggage to be parsimonious, while retaining as many of our intuitive notions as we can. Nihilism commits us to the sparsest ontology and I defend Nihilism against criticisms of counterintuitiveness, and establish it as the best theory of Composition