Mark Heller

Anti-essentialism holds that no thing has any modal properties except relative to a conceptualization—for instance, relative to a description. One and the same thing might be essentially rational relative to the description “mathematician” but only accidentally rational relative to the description “bicyclist.” Anti-essentialism was dominant in pre-Kripkean days. The old description theory of names made room for anti-essentialism by reducing apparently true de re modal attributions to de dicto ones by way of the hidden description. We can follow Kripke in giving up the description theory without thereby giving up anti-essentialism. Counterpart theory makes room for anti-essentialism by interpreting de re modal attributions by way of counterparts and allowing that different other-worldly objects count as a thing’s counterparts relative to different ways of thinking of the thing. One thing is essentially physical when thought of as a body but only accidentally physical when thought of as a person. One thing has its shape essentially when thought of as a statue but only accidentally when thought of as a lump of clay. The metaphysical meat of counterpart theory is that it allows for anti-essentialism.

The best reason to believe in temporal parts is to avoid commitment to coincidence—roughly, two objects occupying exactly the same space at exactly the same time. Most anti-coincidence arguments for temporal parts are fission arguments. Gaining some notice, however, are vagueness arguments. One goal of this paper is to clarify the way a temporal-parts ontology avoids coincidence, and another is to clarify the vagueness argument, highlighting the fact that it too is an anti-coincidence argument. The temporal-parts alternative to coincidence has been challenged on the grounds that it leads to a kind of coincidence of its own. When something that is a temporal part of more than one person thinks about its future self, it must be thinking about a multitude of people. Thus, there must be many people thinking many thoughts in that region occupied by the thinking part. The third goal of this paper is debunking this attack on temporal parts.

This text is devoted to arguing for the thesis that our standard ontology of physical objects is not correct, and to offering a replacement for that ontology. None of the things that we normally take to exist really do exist. There are no animals, vegetables, or minerals. Nothing that I say against the specific physical objects of our standard ontology counts against the general claim that there are physical objects. In fact, I propose an ontology of physical objects that does not suffer from the defects of our standard ontology or from any other defect. What exist, according to the ontology that I propose, are four dimensional hunks of matter, and every filled region of spacetime is exactly filled by one such object. ;In chapter 1, I explain this proposed ontology of four dimensional hunks of matter, give some reason for preferring four dimensional objects over three dimensional ones, and answer some objections to such an ontology. In chapter 2 the ontology is developed in more depth, paying special attention to those features of an object that seem to be most tied to its identity--its persistence conditions and essential properties. It turns out that four dimensional hunks have their spatiotemporal boundaries essentially. I also begin my attack on the standard ontology, offering some reason to believe that they do not really exist, or at least that they do not have the persistence conditions and essential properties that we typically attribute to them. In chapter 3 I present my strongest argument against our standard ontology--a version of the Sorites paradox. I discuss all the possible ways of handling vagueness and show that the only acceptable one is the denial of our standard ontology. In chapter 4 I show that rejecting the standard ontology is not as extreme as it might first seem since another ontology can be offered in its place and a paraphrase can be set up, thereby showing that even our most important and effective utterances need not be committed to the standard ontology. This other ontology is that of four dimensional hunks of matter

This provocative book attempts to resolve traditional problems of identity over time. It seeks to answer such questions as 'How is it that an object can survive change?' and 'How much change can an object undergo without being destroyed'? To answer these questions Professor Heller presents a theory about the nature of physical objects and about the relationship between our language and the physical world. According to his theory, the only actually existing physical entities are what the author calls 'hunks', four-dimensional objects extending across time and space. This is a major contribution to ontological debate and will be essential reading for all philosophers concerned with metaphysics.