Are ordinary things irreducibly real? Are the medium-sized objects that we interact with daily (automobiles, people, trees) really the diverse entities that we take them to be; or are they really something else – perhaps homogeneous things like four-dimensional “spacetime worms” or collections of three-dimensional “simples”? I shall argue that ordinary things are irreducibly real, three-dimensional objects (I'll argue for three-dimensionalism in chapter 10) and that they really are of vastly different kinds. The variety of things is not merely conceptual: variety is not just a matter of different concepts being applied to things that are basically of the same sort. Rather, the differences among ordinary things are ontological: a screwdriver is a thing of a fundamentally different kind from a walnut, and both belong in a complete inventory of what exists. To vindicate such beliefs, I shall propose a nonreductive view of reality that makes sense of the world as it is encountered in ontological – and not just conceptual – terms.

In this chapter, I shall set out, and begin to defend, the particular brand of nonreductionism that I favor – I call it the “Constitution View.” If the Constitution View is correct, then ordinary things are as real as the fundamental entities of physics; ordinary things are irreducible objects, distinct from collections of microphysical entities. My aim is to offer a metaphysical theory that acknowledges the genuine reality of what our everyday concepts (as well as our scientific concepts) are concepts of.