Ontological philosophy is a new way of doing philosophy. Implausible though it may sound at this late date, after more than 2 millennia of trying, there is a new way of doing philosophy. And it is one that works.

Furthermore, since ontological philosophy is a form of naturalism that uses the empirical method, it is equally a new way of doing science. In other words, it unites philosophy and science. Not surprisingly, it has profound and far reaching implications.

Philosophy. Philosophy is different from ordinary ways of knowing. It aspires to a kind of knowledge that is prior to everyday reasoning, such as modern science and everyday practical reasoning. Since it takes a special foundation to defend a more fundamental kind of knowledge, foundationalism is the heart of philosophy. Ontological philosophy is a new kind of “first philosophy.”

In the past, philosophers have used epistemological foundations to argue for more fundamental truths. They used reflection on how we know to arrive at a theory about the nature of reason and knowledge such as the intuition of forms, certainty about ideas in the mind, and the language-users’ understanding of language. Such approaches to justifying a more fundamental kind of knowledge have failed, however, to garner general acceptance (mainly because they lead to metaphysical dualism and skepticism). Indeed, the failure of traditional, “epistemological” philosophy is one of the few points on which most contemporary philosophers can agree.

Ontological philosophy. It is not hard, therefore, to see why we might wish there were a new way of doing philosophy. And there is one. For it is possible to use empirical ontology (the acceptance of whichever ontology is the best ontological explanation of what is found in nature), rather than epistemology, as the foundation for justifying a more fundamental kind of knowledge.

By “ontology,” I mean a theory about the basic substances that constitute the world, where “substances” are self-subsistent entities that never come into existence and never go out of existence. That is what we implicitly assume when we take objects in the natural world to exist independently ourselves. They must be made of something that can exist on its own, or else they would depend on us. (And they must be related to one another in some way to exist together as a world.) To be the best ontology, as the empirical method requires, however, such a theory would have to postulate the fewest and simplest basic substances (and basic relationship) that can explain everything in the world.

Suppose there were an ontology that is demonstrably better than any alternative, including those offered by physics. And suppose that it entailed further propositions about the world that were not already recognized as true. Such an ontology would be a foundation for philosophy, for what else it implied would be ontologically necessary. Its implications could be denied only by giving up the best ontological explanation of the world. They would be ontologically necessary truths. Such truths would be more fundamental than and, thus, prior to what is known by ordinary means.

As it happens, there is such an ontology. It is “spatiomaterialism,” the theory that the world is constituted by space as well as matter enduring through time as substances. It is a better ontological explanation of the world than any alternative currently considered by naturalists. And it has many implications about the world that are not currently recognized as true, much less as necessary. It does what philosophy has always aspired to do.

The main reason that naturalists do not already accept spatiomaterialism is that they do not choose which ontology to believe by inferring to the best ontological-cause explanation of the world. Instead, they believe in empirical science, which infers to the best efficient-cause explanations of what happens in the world, and they accept whatever ontology is required for scientific theories to be true. The Einsteinian overthrow of the Newtonian belief in absolute space and time has led naturalists to assume that space cannot be a substance enduring through time. But, as will be shown below (under Change), it is possible to explain the truth of both Einstein’s special and general theories of relativity on the assumption that space endures through time (and, thus, is absolute). That is clearly a better ontological explanation of the world than ontologies derived from realism about theories in physics, because it is simpler and less puzzling than the belief that spacetime is what contains all the matter in the world.

Spatiomaterialism is also better than forms of materialism that take it for granted that bits of matter have spatial relations and that spatial relations can change over time, for it explains why they have spatial relations and how change is possible. Furthermore, since spatiomaterialism can explain the truth of all the other basic laws of physics, science offers no reason to doubt that it is true.

Empirical ontology affords, therefore, a way of doing philosophy that is not currently being considered. And as we shall see, it has many profound consequences.

Epistemological philosophy. Ontological philosophy is different from traditional philosophy, because philosophers have traditionally taken an epistemological approach. They tried to demonstrate more fundamental truths about the world than ordinary ways of knowing by taking as their foundation a theory about the nature of reason which was arrived at in some way by reflecting on how we know. Those truths were called “necessary,” but since the foundation was epistemological, rather than ontological, all that could be accomplished was to show that they are certain. In epistemological philosophy, what distinguishes necessary truths from ordinary knowledge is certainty (rather than being entailed by a deeper explanation of the world). Certainty is epistemological necessity.

To be sure, the systems constructed by the most ambitious epistemological philosophers had ontologies, and the claims they made about substances were supposed to be necessary. But these ontological truths were not ontologically necessary; they were truths about ontology that were supposed to be epistemologically necessary, or certain. That is because ontology is just an afterthought in traditional philosophy. The primary goal is to show the conclusiveness of the certain propositions about the world. But insofar as those necessary truths entailed theories about what exists, epistemological philosophers found themselves committed to some ontology or other. In other words, their ontological theories, or metaphysical systems, as they are called, were just implications of their epistemologically necessary truths, not their foundations.

Furthermore, these implications were unwelcome in the end, for their metaphysical systems inevitably cast doubt on their epistemological argument, leading to skepticism. Since success in epistemological philosophy comes from demonstrating that something beyond the epistemological foundation can be known (or so-called realism), it entails a problematic ontological dualism of some kind. In addition to whatever accounts for the existence of their epistemological foundation, epistemological philosophers find themselves committed to the existence of the other kind of substances whose reality they are demonstrating, and as it happens, it is never easy to explain how such different kinds of substances fit together as parts of a single world. Thus, realism leads by way of some problematic ontological dualism to anti-realism, or skepticism about the reality of what is supposed to be demonstrated, and the failure of epistemological philosophy in inevitable.

The foundation of ontological philosophy. Though ontological philosophy is based on ontology, rather than epistemology, it must also secure its foundation. That requires defending a specific theory about the nature of the world, and as mentioned above, the specific theory that will be defended here is spatiomaterialism. It cannot be justified by reflecting on how we know without reducing to epistemological philosophy. By calling it “empirical ontology,” I mean to suggest that it is justified empirically. Before saying what I mean by the empirical method, however, let me say a bit more about the other two assumptions on which spatiomaterialism will be justified.

Naturalism. The following defense of spatiomaterialism assumes that what is being explained by empirical ontology is the natural world. By the natural world, I mean everything in space and time. This is a form of naturalism, for it is to assume that the world is just the natural world.

This kind of naturalism is implicitly assumed by natural science. Naturalism is implicit in science’s commitment to the empirical method, for science has traditionally limited the evidence that is relevant in choosing among theories to observation, or what can be known by perception. Everything that can be known by perception is located in space and time.

Reflection, by contrast, has been excluded by the empirical method of traditional science. That has enabled science to set aside the reflection-based epistemological theories of traditional, epistemological philosophy. Ontological philosophy also relies mainly on perception.

But there is no principled reason to exclude reflection as a source of information about the natural world. Reflective subjects are, after all, parts of the natural world, and in the end, an ontology of the natural world will have to explain what is known about the world through reflection as well as what is known through perception. What is still excluded from ontological philosophy, however, is the use of reflection as a foundation for proving necessary truths. The foundation of necessary truths in ontological philosophy is the ontological explanation that best explains what is perceived. Only ontologically necessary truths are justified from its ontological foundation. As it turns out, however, spatiomaterialism puts ontological philosophy in a position to explain why it has seemed that some propositions can be known with certainty.

Ontological explanation. What makes it possible for empirical ontology to be used as a philosophical foundation is the recognition that ontology can be a kind of explanation. "Ontology" means, literally, "theory of being." It is a theory about the nature of existence, and ontology can be explanatory, if existence can be reduced to basic substances and how they exist together as a world. That is to assume that substances, as substances, are self-subsistent entities. Since basic substances exist on their own, each distinct from all other substances in the world, it may be possible to explain everything in the world by showing how it is constituted by basic substances of certain kinds with a certain basic relationship to one another.

For naturalists, the world in which everything is to be explained ontologically is the natural world, or what is found in space and time. But to explain everything in such a world is not merely to explain the existence of the objects in space. It is to explain all their properties, their relations to one another, and how properties and relations change as time passes. In other words, the natural world can come down to a few basic kinds of substances related in certain basic ways only if that can explain everything in the natural world and everything about the natural world. The inability to explain the possibility of some aspect of the world would show that the world is not constituted by the basic substances and relationships postulated by the ontology.

Empirical method. When ontology is understood as a kind of explanation, it is possible to use the empirical method to choose which specific ontology to believe. By the empirical method, I mean the method used by science. I assume that that method is basically an inference to the best explanation of what is found in the natural world. Thus, by empirical ontology, I mean the project of inferring to the best ontological explanation of what is found in the natural world.

No attempt will be made to justify the empirical method. Justifying the empirical method is a road traveled by traditional philosophy, and ontological philosophy takes a different road by simply using the empirical method, as science does. This way of judging between conflicting theories is what beings like us do naturally. (Later, when we take up necessary truths about evolution, we will trace that disposition to the function of the brain and how the brain works.)

Our main departure from empirical science is, therefore, to apply the empirical method to ontology, rather than just to theories about efficient causes of what happens. That is, we shall be deciding what to believe about the nature of what exists in the world, rather than only what to believe about the causes of what happens there.

More precisely, we shall infer to the simplest and fewest basic substances (and basic relationship among them) that can explain everything in the world, that is, every kind of object in the natural world and every aspect of the natural world, including those which have to do with how things change over time.

Ontological science. Empirical ontology affords, therefore, a way of doing philosophy that is not currently being considered. It is equally, however, a new way of doing science, because ontological philosophy is tantamount to recognizing ontology as a more basic branch of natural science than physics. That means that the basic substances (and basic relationship) discovered by empirical ontology must be able to explain the truth of all the basic laws of physics, much as physics has often been thought to explain the laws of less basic branches of science, such as chemistry and biology. But that does not mean that science is any less empirical, not as long as ontology also uses the empirical method. Nor is this a trivial or meaningless change in science, for it makes all the explanations of less general sciences reducible to the most basic branch of (ontological) science.

Ontology is not, however, quite like other branches of science, because its uses substances, rather than laws of nature, to explain what is found in the world. That is the difference between ontological-cause explanations and efficient-cause explanations. Efficient-cause explanations depend on laws of nature to connect efficient causes to their effects, and accordingly, to infer to the best efficient-cause explanations is to attempt to discover the simplest and most comprehensive laws describing the regularities found in nature. But the causes in ontological explanation are the basic substances and the basic relationship among them, and since things are explained ontologically by showing how they are constituted by substances, ontological explanations do not depend on laws of nature. Ontological explanations show how basic substances are identical to what is found in the world. And since the laws of nature are explained ontologically (by showing how the basic substances and relationships postulated by the ontology make the laws true), the explanations given by ontological science all cite substances as causes in the end.

It is now widely recognized that laws in less general branches of science are not reducible to the laws of physics. But as we shall see, when empirical ontology is seen as the most basic branch of natural science, it is possible to reduce not only the basic laws of physics, but also the laws of all the less general branches of natural science, including biology, physiology, and the social sciences, to the best explanation in the most basic branch of science.

To be sure, it is an ontological reduction, rather than scientific reduction (or reduction to the laws of physics). But in “ontological science,” all the theories of the less general branches of natural science can be reduced to the most basic branch, accomplishing a great unification of scientific knowledge.

That is how empirical ontology unites philosophy and science. But a difference between them can still be discerned because of their different interests. While philosophy sees empirical ontology as a foundation for defending ontologically necessary truths about the world, science sees it as a way of explaining the truth of theories in physics and other branches of science.

That is, the recognition that ontology is a more basic branch of empirical science than physics introduces the project of discovering the simplest and fewest kinds of basic substances that can explain the truth of the laws of physics. That is spatiomaterialism, and combined with the truth of the laws of physics, it entails the ontological necessary truths by which all the theories in less general branches of science are reduced to a simple ontological theory.

the Wholeness of the World. The reason for calling this philosophical argument “the Wholeness of the World” is that spatiomaterialism explains everything in the world. As an ontological theory, spatiomaterialism must be able to account for (in the sense of explaining the possibility of) everything found in the world, including not only all the objects in space, but all their properties, relations and how they change. But it can lead to new beliefs about the world only by demonstrating ontologically necessary truths about the world. In some cases, what is new is just recognizing the necessity of what is already believed to be true, but in other cases, the beliefs themselves are new. It is the completeness of its ontological explanation in this latter sense that earns this argument the title, "the Wholeness of the World." Once spatiomaterialism is elaborated in a way that can explain why the basic laws of physics are true, its implications hold in every possible spatiomaterial world like our own, and those ontologically necessary truth explain the nature of the world in a most complete way. How complete it is can be suggested by mentioning that it explains all the puzzling phenomena that seem to lie beyond the limits of science and have raised doubts about naturalism, including consciousness, goodness, and even how there can be something worthy of worship, or holiness, in a strictly natural world. What makes this possible are its implications about the nature of evolutionary change, and the completeness of this theory of evolution is evident in how many organisms in our world turn out to have essential natures, including not only plants and animals, but also subjects like us who come to know that the world is whole in this way. But it will not be possible to explain fully what all is meant by “the wholeness of the world” until the conclusion, because its various aspects fit together in a way that makes the world even more whole than can be seen at first.

Insofar as it is a complete explanation the nature of the world, it is not merely an explanation of the world. It is the explanation of the world. That is the sense in which it is the Absolute Truth. This is to deny the conceptual relativism of contemporary kantians, like Hillary Putnam, because there is no other theory that can explain everything in and about the world as simply as one based on spatiomaterialism. Ontological philosophy is the "metaphysical realism," the "One True Theory," and the "God's Eye View" of the world whose possibility is denied by such so-called internal realists.