Underlying the fundamental structure of intellectual property law — specifically, the division between copyright and patent law — are at least two substantive philosophical assumptions. The first is that artistic works and inventions are importantly different, such that they warrant different legal systems: copyright law on the one hand, and patent law on the other. And the second is that particular artistic works and inventions can be determinately individuated from each other, and can thereby be the subjects of distinct and delineated legal rights. But neither the law nor existing scholar- ship provides a comprehensive analysis of these categories, what distinguishes them, or why their distinctions should matter to law.

This Article seeks to substantiate and unify these assumptions, taking the most striking doctrinal difference between copyrights and patents as its theoretical starting point: namely, that copyright law has an independent creation defense while patent law does not. Endeavoring to vindicate this doctrinal distinction with a theory of what distinguishes the paradigmatic subject matters of copyrights and patents, this Article defends the view that artistic works are author-individuated, while inventions are structure-individuated. It draws on philosophical thinking, thought experiments, and existing practices surrounding expression and functionality to argue that, although two distinct inventive acts can result in the very same invention, two distinct acts of authorship — even ones resulting in works that are “structurally” identical — cannot result in the very same artistic work, because the identity of the author in part makes the work what it is. The Article explains how these “individuation theses” vindicate, not just copyright and patent law’s differential treatment of independent creation, but other core features of intellectual property’s defining bifurcation, and then goes on to analyze the theses’ implications for different theories of what justifies intellectual property rights. Finally, the Article explores aspects of existing law that might be in tension with this conception of artistic works and inventions and thus ought to be revised to better reflect and incorporate it, if the individuation theses are indeed getting things right.