Limits of Reality

Limits of Reality

We speak of the limits of human knowledge or reason or our conceptual scheme, but we don’t tend to talk about the limits of reality. Knowledge is limited relative to reality—it is not as extensive as reality—but reality cannot fail to be as extensive as itself. But it may be less extensive than some conceivable alternative, so that there is at least a sense to the question. Is there some type of reality that is less limited than our reality? Or is our reality—actual reality—unlimited, perhaps essentially so? This seems like an interesting metaphysical question, though not one I have seen asked. People have certainly discussed the question of the infinity of the universe (Spinoza), but that is not the question I have in mind. We can agree that numbers, space and time are infinite, and therefore limitless, but a universe containing only one of these things—or all of them—would still be limited in the sense I intend, because there would be many perfectly conceivable things that would not exist in such a universe. The series of numbers has no limit, but a world of only numbers would be vastly more limited than our world. An infinite world can be a sharply limited world—an ontologically impoverished world. Intuitively, we are speaking here of how many kinds of thing there are; and the question is whether our world is maximal in this respect.

            Suppose we think that reality consists of three kinds of thing: physical, mental, and abstract. Is this a limited number of kinds of thing? Could there have been many more kinds of thing (ontological categories)? Apparently not: we can’t imagine any further basic type of entity that just contingently happens not to exist in our world. A hard-nosed materialist might contend that nothing could exist that is not material, so that a purely material world is not a limited world (relative to some conceivable world). Of course, there could be many more particular material things, but there may be no limitation in the kinds of things that exist. Similarly, there is limitation in the animal species that exist (or chemical substances), but that entails no limitation of basic categories. A world without life is more limited than a world with life, but not a world without cockroaches. If our world lacks deities, then it is limited relative to a world that has them; so it might be a fundamentally limited world (or it might not be if there are deities in it).

            Consider laws of nature and logic. They constrain what can happen, so they function as principles of limitation. In a world without such laws there would be no limitation on what can happen. That is a very different world from ours (though it may not be a genuinely possible world). Moreover, there are only a few basic laws of nature in our world; maybe there are worlds containing many more basic laws (could there be more logical laws in some possible world?). We can think of these laws as laws of limitation: they force our world to be limited in certain ways. A law tells you what can and will happen, but also what can’t and won’t happen. Or consider the speed of light: this imposes a limit on the speed of any projectile. Objects are not at liberty to move at any arbitrary speed; there is a sharp limitation. Likewise the universe is not free to reverse entropy; it is limited to increasing disorder.

            Limitation is the flipside of possibility. If something has a certain nature (and everything does), then it has a range of possibilities and a range of impossibilities. This is as true for whole universes as it is for individual objects. Limitation is thus normal, predictable, and inescapable. Part of the nature of our universe is to be infinite in various ways, but this does not negate the fact that it is a limited reality. We marvel at the richness of nature, its extent, its possibilities, but in fact it is quite sharply limited. It is more limited than our imagination (which itself is limited by our nature as cognitive beings). We might even say that reality is subject to ontological closure: it is not unlimited in what it contains. Space, say, though infinite in extension, is quite confined with respect to its dimensions—having only three (or nine if you follow certain versions of string theory). The brain is quite limited in its physical nature, consisting of only certain chemicals in certain structures and subject to certain forces. Cognitive closure is one kind of ontological closure—one kind of natural limitation. Gravity prevents bodies from moving in certain ways, and the brain’s physical construction prevents it from functioning in certain ways, including cognitively. Everything has limitation built into it, despite its impressive range of potentialities. The whole universe is accordingly an entity subject to inherent limitations. We don’t appreciate these limitations because we experience only this universe—while we experience many different kinds of individual objects—but our universe may be quite sparsely populated and inept compared to other possible universes. The universe might give rise to an illusion of richness: we are awestruck by its variety but only because we know nothing better. Maybe God kept it nice and simple so as not to overburden our limited minds; other universes might make ours look simple and dull. After all, our universe began in something quite lumpen and undifferentiated—the Big Bang—and it can only reflect that initial event. Surely the material condition of the universe at that point was sharply limited by the prevailing physics, and the subsequent history of the universe consists of iterations of what was then present. Reality is limited by the initial conditions that made it possible.

            When we contemplate the galaxies and the variety of species and our own minds we are stuck by the richness of the universe, even conceiving it as limitless, but this is an anthropocentric perspective. To a more objective point of view the world must appear as confined—as just one type of reality amid others. It may not be the least interesting of all possible worlds, but it may be far less interesting than we tend to suppose. It may be a garage sale compared to the Harrods of some other world. In pre-Socratic style we might picture the universe as the product of forces of expansion and constraint. Many new things come into existence, expanding the inventory of things the universe contains; but this happens against a background of curtailment as the universe prevents things from happening and possible things from being formed. It limits as it creates. It is as preventive as it is generative. It operates with an ontological Occams’s razor, ruthlessly paring away at reality. When God created the universe he created limitation on being as well as plenitude, denial as well as affirmation.