Parts and Wholes

The Odd Universe Argument aims to show that from four intuitive assumptions about parts and wholes, we can conclude a priori that there is an odd number of things in the universe. This Element is an opinionated survey of philosophical issues involving parthood, composition, identity, and counting, guided by an investigation into where this argument has gone awry. We first walk through some general methodology, basic mereology, and plural logic. Next, we explore questions about the nature of composition and decomposition. Does composition always occur? Never? Sometimes? Is the universe, at rock bottom, just many partless bits (simples)? Or do the parts have parts all the way down (gunk)? We then turn to arguments for and against the thesis that composition is identity, with a healthy bias in its favor. We conclude with a return to the odd universe argument, and my thoughts on how best to solve it.