Eric T. Olson

Constitutionalism says that qualitatively different objects can be made of the same matter at once. Critics claim that we should expect such objects to be qualitatively indistinguishable. E.J. Lowe thinks this complaint is based on the false assumption that differences in the way things are at a time must always be grounded in how things are at that time, and that we can answer it by pointing out that different kinds of coinciding objects are subject to different composition principles. I argue that he is mistaken on both counts

Many philosophers say that two or more people or thinking beings could share a single human being in a split-personality case, if only the personalities were sufficiently independent and individually well integrated. I argue that this view is incompatible with our being material things, and conclude that there could never be two or more people in a split-personality case. This refutes the view, almost universally held, that facts about mental unity and disunity determine how many people there are. I suggest that the number of human people is simply the number of appropriately endowed human animals.

In this paper I shall explore a novel alternative to these familiar views. In his recent book Sub ects of Ex erience, E. J. Lowe argues, as many others have done before, that you and I are not animals. It follows from this, he says, that we must be simple substances without parts. That may sound like Cartesian dualism. But Lowe is no Cartesian. He argues from premises that many present-day materialists accept. And he claims that our being mereologically simple is consistent with our having such paradigmatically physical properties as being six feet tall and weighing 160 pounds. You and I, he claims, are mereological atoms shaped like human beings

From the time of Locke, discussions of personal identity have often ignored the question of our basic metaphysical nature: whether we human people are biological organisms, spatial or temporal parts of organisms, bundles of perceptions, or what have you. The result of this neglect has been centuries of wild proposals and clashing intuitions. What Are We? is the first general study of this important question. It beings by explaining what the question means and how it differs from others, such as questions of personal identity and the mind-body problem. It then examines in some depth the main possible accounts of our metaphysical nature, detailing both their theoretical virtues and the often grave difficulties they face. The book does not endorse any particular account of what we are, but argues that the matter turns on more general issues in the ontology of material things. If composition is universal--if any material things whatever make up something bigger--then we are temporal parts of organisms. If things never compose anything bigger, so that there are only mereological simples, then we too are simples--perhaps the immaterial substances of Descartes--or else we do not exist at all (a view Olson takes very seriously). The intermediate view that some things compose bigger things and others do not leads almost inevitably to the conclusion that we are organisms. So we can discover what we are by working out when composition occurs.