Mark Heller

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.

René Descartes, one of the dominant figures in the history of philosophy, has been accused of one of the most obvious mistakes in the history of philosophy — the so-called cartesian circle. It is my goal in this paper to arrive at an understanding of Descartes's work that attributes to him a theory that should be of philosophical interest to contemporary epistemologists, is consistent with, and suggested by, the actual text, and avoids the circle.I begin with a brief explanation of the supposed circle. In his search for absolute certainty Descartes requires that in order for a proposition to be an instance of knowledge it must be indubitable for the knower, and in order for it to be indubitable for the knower she must be able to eliminate any possibility of the belief's being false. It is to provide a means to satisfy this requirement that Descartes proposes the principle whatever is clearly and distinctly perceived cannot be false.And it seems that Descartes's defense of CD traps him in the circle.