Why Does the World Exist: An Existentia - By Jim Holt Page 0,2
existed. Or perhaps it popped into being with no cause at all. In either case, its existence is just a “brute fact.”
The brute-fact view denies that the universe as a whole requires any explanation for its existence. It thus avoids the need to posit some sort of transcendental reality, like God, to answer the question Why is there something rather than nothing? Yet, intellectually, this feels like throwing in the towel. It’s one thing to reconcile yourself to a universe with no purpose and no meaning—we’ve all done that on a dark night of the soul. But a universe without an explanation? That seems an absurdity too far, at least to a reason-seeking species like ourselves. Whether we realize it or not, we instinctively hew to what the seventeenth-century philosopher Leibniz called the Principle of Sufficient Reason. This principle says, in effect, that explanation goes all the way up and all the way down. For every truth, there must be a reason why it is so and not otherwise; and for every thing, there must be a reason for that thing’s existence. Leibniz’s principle has been mocked by some as a mere “metaphysician’s demand.” But it is a bedrock principle of science, where it has been notably successful—so successful, indeed, that one might say it is true on pragmatic grounds: it works. The principle seems to inhere in reason itself, since any attempt to argue for or against it already presupposes its validity. And if the Principle of Sufficient Reason is valid, there must be an explanation for the existence of the world, whether we can find it or not.
A world that existed for no reason at all—an irrational, accidental, “just there” world—would be an unnerving one to live in. So, at least, claimed the American philosopher Arthur Lovejoy. In one of his 1933 lectures at Harvard on the “Great Chain of Being,” Lovejoy declared that such a world “would have no stability or trustworthiness; uncertainty would infect the whole; anything (except, perhaps, the self-contradictory) might exist and anything might happen, and no one thing would be in itself even more probable than any other.”
Are we then doomed to choose between God and the deep brute Absurd?
This dilemma has lurked in the suburbs of my mind ever since I first hit upon the mystery of being. And it has moved me to ponder just what “being” amounts to. The philosopher’s term for the ultimate constituents of reality is “substance.” For Descartes, the world consisted of two kinds of substance: matter, which he defined as res extensa (“extended substance”), and mind, which he defined as res cogitans (“thinking substance”). Today, we have pretty much inherited this Cartesian outlook. The universe contains physical stuff: Earth, stars, galaxies, radiation, “dark matter,” “dark energy,” and so forth. It also contains biological life, which, science has revealed, is physical in nature. In addition, the universe contains consciousness. It contains subjective mental states like joy and misery, the experience of redness, the feel of a stubbed toe. (Are these subjective states reducible to objective physical processes? The philosophical verdict is still out on that question.) An explanation is just a causal story involving items from one or the other of these ontological categories. The impact of the bowling ball caused the pins to drop. Fear of a financial crisis caused a stock market sell-off.
If that’s all there is to reality—matter-stuff and mind-stuff, with a web of causal relations between them—then the mystery of being looks hopeless indeed. But perhaps this dualistic ontology is too impoverished. I myself began to suspect as much when, following my teenage flirtation with existentialism, I became infatuated with pure mathematics. The sort of entities mathematicians spend their days pondering—not just numbers and circles, but n-dimensional manifolds and Galois systems and crystalline cohomologies—are nowhere found within the realm of space and time. They’re clearly not material things. Nor do they seem to be mental. There is no way, for example, that the finite mind of a mathematician could contain an infinity of numbers. Then do mathematical entities really exist? Well, that depends on what you mean by “existence.” Plato certainly thought they existed. In fact, he held that mathematical objects, being timeless and unchanging, were more real than the world of things we perceive with our senses. The same was true, he held, of abstract ideas like Goodness and Beauty. To Plato, such “Forms” constituted genuine reality. Everything else was mere appearance.