An ontology aims at more than a catalogue of categories of entities. It also aspires to be a system. The way things and properties or things and events fit together is as important for an ontology that admits such entities as the considerations requiring their existence. Two matters are central to any system of categories and in particular to this one that as a system of categories for physical reality I have called a physical ontology. First, the ontologist needs to ask whether entities of one category depend on those of another. Are things and properties independent in the way dogs and cats are, and if they are, is there still some other way that there is dependency between them? Second, there is a question about sameness. People and their coats are surely distinct, but can this model be applied to things and their properties, to things and their actions, and to things and their physical parts?
Certain chronic philosophical infirmities can be traced to a familiar view about dependence and sameness. On the one hand, this view limits dependencies between entities to causal dependencies of the familiar sort. One entity may wound, convince, or beget a second, and then the second is dependent in some respect on the first. But this causal dependence is supposed to be the only kind. There is no ontological dependence of entities of one category on those of a second whereby the former become secondary or dérivative and the later primary or fundamental. On the other hand, this view treats entities of different categories as distinct. For a property, action, or part of a thing is quite naturally taken to be distinct from the thing since none of the former is ontologically dependent on the latter. This amounts to an extension of the principle that discernibly different things are not the same. A property, action, or part of a thing must, in this view, be distinct from the thing because of a discernible difference between them. The principle is extended here to apply not just to things but to entities in different categories.
This view of the independence and distinctness of entities of different categories turns certain seemingly harmless dualisms into untenable ones. The dualisms between things and properties, agents and their actions, stuffs and their constituent atoms, and persons and minds become similar in all important respects to the dualisms between cats and dogs, persons and coats, and pilots and ships. As a result, the dualisms between entities of different categories call for a reduction of the entities of one kind to those of the other kind in each pair. For the strict independence and distinctness attributed to entities of the different kinds in these pairs generate undesirable consequences. It is immaterial here which way the reduction goes-things to properties, or properties to things; things to events, or events to things. The important matter is that reductionism does not challenge but is in fact a consequence of the claim that entities of different categories are related by independence and distinctness. Reductionism also has its problems, however. As the inadequacy of reductionism to cope with all the facts becomes more evident, an antireductionist reaction starts the cycle over again by positing the original dualisms in their untenable form.
One way to break out of this cycle of dualism and reductionism is to change the view of dependence and sameness that is integral to it. Yet, at least on the matter of sameness, opinion is so conservative that any attempt to tamper with it merely to avoid difficulties on the seemingly quite different matter of traditional dualisms will fail to gather much support. A more direct argument must be attempted here. The crucial claim in this argument concerns both sameness and necessity. It is that unless things can have components not distinct from them, there are no necessities for these things to be and to behave in certain ways. There are entities, commonly called natures, that are inherent in the sense that they both depend on the things with them and are not distinct from those things. Otherwise, there are no necessities for these things to be and to behave in certain ways. With this exception established, strict independence and distinctness are easily seen to fail in other cases as well.
The necessities requiring inherent natures are not offshoots of concepts or language. But it is easy to see why, if entities in different categories are always distinct, there can be no real, as opposed to intentional, necessity. If a thing is distinct from its nature, its properties, its actions, and its parts, it is a simple entity. There is then nothing about it alone that influences what it is or does. The necessity of a thing to be or to behave in a certain way cannot be due to what it is, if it is a simple. It can be due only to the concept or term under which we place it.
Unfortunately for any conceptualist or linguistic view of necessity, the need for real necessities is evident from an examination of the requirements of a coherent inductive practice. Such an examination is, thus, a crucial part of my argument. As noted, a conceptualist or linguistic view of necessity is implied by distinctness between entities of all categories. The inadequacy of this intentionalist view of necessity in respect to inductive practice means that entities from certain different categories are not distinct. This, in turn, will imply that there are dependencies between entities of certain categories. With these results, we are able to break out of the cycle of dualism and reductionism.
The shift to the unorthodox view that entities of different categories need not be independent and distinct has interesting con- sequences for a number of philosophical issues. Relations, actions, time, capacities, and events are surveyed below from the new point of view. A work with such a broad scope is inevitably programmatic. It shares with other programmatic work a drawback for the reader seeking solutions to problems formulated in terms of principles current in the profession. It attempts to give reasons for formulating those problems on a different base.
The treatment of temporal asymmetry, for example, adds nothing toward the solution of the problem of temporal asymmetry conceived as a problem in scientific ontology. It attempts to justify alternative principles, and it suggests how one may advance if the same problems are formulated in terms of these principles. One principle behind the treatment of temporal asymmetry in scientific ontology is that actions are sequences of states. This view of action is shown to lead to difficulties. An alternative view is developed in terms of which it is possible to solve the problem of temporal asymmetry without the scientific ontologist's reliance on scientific results. The difficulties raised for this and other current ontological principles may not turn out to be sufficiently damaging to make the general program adopted here a compelling one. Still, the attempt will have been amply rewarding if only it occasions the formulation of stronger defenses for the accepted principles.
Anticipations of some of the specific themes, but not of the general plan, have already appeared. Chapters IV and V take a different approach to the conclusion already argued for in "Are There Necessary Connections in Nature?״ from Philosophy of Science (37, 1970, pp. 385-404). Chapter X is a development of an essay with the same title, "Capacities and Natures," appearing in Boston Studies in Philosophy of Science, VIII (R. C. Buck and R. S. Cohen, eds., Reidel, Dordrecht, 1972, pp. 49-62). A very early version of Chapter I appeared as "Naturphilosophie״ in Sowjetsystem und Demokratische Gesellschaft, VI (C. D. Kernig, ed., Herder, Freiburg, pp. 40-46, 1972). The thesis of Chapter VI was argued for in less convincing ways in "Analyticity and Conceptual Revision" from The Journal of Philosophy (63, 1966, pp. 627-37) and in "A Modal Analogue of Free Logic" from The Logical Way of Doing Things (K. Lambert, ed., Yale, New Haven, 1969, pp. 147-84). Chapter VII is simply a fuller version of "Relatedness Without Relations" appearing in Nous (6, 1972, pp. 139-51).
My first serious questioning in the field of physical ontology was influenced in different ways by a number of post-phenomenalist contemporaries, notably Grünbaum, Wilfrid Sellars, and Strawson. While welcoming their realism, I felt the need of extending it to provide a realistic account of necessity. In regard to necessity, post- phenomenalist realists are, regrettably, still the disciples of Hume. Gradually then the central issues in physical ontology took shape for me in the context of the contrast, not between phenomenalism and realism, but between ontologies that prohibit and those that allow a realistic account of modalities. This contrast came to be identified for me with that between ontologies in which the primary entities are simples, in the way that Hume's impressions are simples, and ontologies in which the primary entities are complexes, as they were for Aristotle. This polarity provides the stage for the major events in what follows.
Most Anglo-American contemporaries rely on an ontology of simples. Thus I have been able to rely on them for little more than technical props, and I have had to look generally to earlier traditions for suggestions about an ontology of complexes. Once the need for a realistic account of necessity is established, the gen- eral methodology adopted in what follows is to look for those ontological principles that are required by such an account.
I am grateful to students from seminars both at Yale and Indiana who, between 1963 and 1970, advanced many useful criticisms of this book in the various stages of its development. To my friends James Bogen, Ernan McMullin, Richard Rorty, and Angus Ross I owe thanks for suggestions on certain of the chapters and for encouragement on the entire project. I am indebted to my col- league Reinhardt Grossmann for having communicated something of his belief in the purity of ontology in the sense of its indepen- dence of linguistic and logical concerns, and, posthumously, to my teacher Arthur Pap for having generated an abiding philosophical interest in problems of necessity. For assistance in readying the manuscript for publication I am grateful to Walter Albee and Wanda Lee Smith. In writing this book I received constant en- couragement from my wife, Ruth, who endured many sacrifices for it.