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Physicists have been giving philosophers a hard time lately. Stephen Hawking claimed in a speech last year that philosophy is “dead” because philosophers haven’t kept up with science. More recently, Lawrence Krauss, in his book, “A Universe From Nothing: Why There Is Something Rather Than Nothing,” has insisted that “philosophy and theology are incapable of addressing by themselves the truly fundamental questions that perplex us about our existence.” David Albert, a distinguished philosopher of science, dismissively reviewed Krauss’s book: “all there is to say about this [Krauss’s claim that the universe may have come from nothing], as far as I can see, is that Krauss is dead wrong and his religious and philosophical critics are absolutely right.” Krauss — ignoring Albert’s Ph.D. in theoretical physics — retorted in an interview that Albert is a “moronic philosopher.” (Krauss somewhat moderates his views in a recent Scientific American article.)
Krauss’ mistake: his belief that scientific experiment is the “ultimate arbiter of truth” about the world.
I’d like to see if I can raise the level of the discussion a bit. Despite some nasty asides, Krauss doesn’t deny that philosophers may have something to contribute to our understanding of “fundamental questions” (his “by themselves” in the above quotation is a typical qualification). And almost all philosophers of science — certainly Albert — would agree that an intimate knowledge of science is essential for their discipline. So it should be possible to at least start a line of thought that incorporates both the physicist’s and the philosopher’s sensibilities.
There is a long tradition of philosophers’ arguing for the existence of God on the grounds that the material (physical) universe as a whole requires an immaterial explanation. Otherwise, they maintain, the universe would have to originate from nothing, and it’s not possible that something come from nothing. (One response to the argument is that the universe may have always existed and so never came into being, but the Big Bang, well established by contemporary cosmology, is often said to exclude this possibility.)
Krauss is totally unimpressed by this line of argument, since, he says, its force depends on the meaning of “nothing” and, in the context of cosmology, this meaning depends on what sense science can make of the term. For example, one plausible scientific meaning for “nothing” is “empty space”: space with no elementary particles in it. But quantum mechanics shows that particles can emerge from empty space, and so seems to show that the universe (that is, all elementary particles and so the things they make up) could come from nothing.
But, Krauss admits, particles can emerge from empty space because empty space, despite its name, does contain virtual fields that fluctuate and can give empty space properties even in the absence of particles. These fields are governed by laws allowing for the “spontaneous” production of particles. Virtual fields, the philosopher will urge, are the “something” from which the particles come. All right, says Krauss, but there is the further possibility that the long-sought quantum theory of gravity, uniting quantum mechanics and general relativity, will allow for the spontaneous production of empty space itself, simply in virtue of the theory’s laws. Then we would have everything — space, fields and particles — coming from nothing.
But, the philosopher says, What about the laws of physics? They are something, not nothing—and where do they come from? Well, says Krauss — trying to be patient — there’s another promising theoretical approach that plausibly posits a “multiverse”: a possibly infinite collection of self-contained, non-interacting universes, each with is own laws of nature. In fact, it might well be that the multiverse contains universes with every possible set of laws. We have the laws we do simply because of the particular universe we’re in. But, of course, the philosopher can respond that the multiverse itself is governed by higher-level laws.
At every turn, the philosopher concludes, there are laws of nature, and the laws always apply to some physical “stuff” (particles, fields, whatever) that is governed by the laws. In no case, then, does something really come from nothing.
It seems to me, however, that this is a case of the philosopher’s winning the battle but losing the war. There is an absolute use of “nothing” that excludes literally everything that exists. In one sense, Krauss is just obstinately ignoring this use. But if Krauss knew more philosophy, he could readily cite many philosophers who find this absolute use — and the corresponding principle that something cannot come from nothing — unintelligible. For an excellent survey of arguments along this line, see Roy Sorensen’s Stanford Encyclopedia article, “Nothingness.”
But even if the question survives the many philosophical critiques of its intelligibility, there have been strong objections to applying “something cannot come from nothing” to the universe as a whole. David Hume, for example, argued that it is only from experience that we know that individual things don’t just spring into existence (there is no logical contradiction in their doing so). Since we have no experience of the universe coming into existence, we have no reason to say that if it has come to be, it must have a cause. Hume and his followers would be entirely happy with leaving the question of a cause of the universe up to empirical science.
While Krauss could appeal to philosophy to strengthen his case against “something cannot come from nothing,” he opens himself to philosophical criticism by simply assuming that scientific experiment is, as he puts it, the “ultimate arbiter of truth” about the world. The success of science gives us every reason to continue to pursue its experimental method in search of further truths. But science itself is incapable of establishing that all truths about the world are discoverable by its methods.
Precisely because science deals with only what can be known, direct or indirectly, by sense experience, it cannot answer the question of whether there is anything — for example, consciousness, morality, beauty or God — that is not entirely knowable by sense experience. To show that there is nothing beyond sense experience, we would need philosophical arguments, not scientific experiments.
Krauss may well be right that philosophers should leave questions about the nature of the world to scientists. But, without philosophy, his claim can only be a matter of faith, not knowledge.
Gary Gutting is a professor of philosophy at the University of Notre Dame, and an editor of Notre Dame Philosophical Reviews. He is the author of, most recently, “Thinking the Impossible: French Philosophy since 1960,” and writes regularly for The Stone.