Speculative philosophy is the term I've used throughout this blog to describe my own philosophical approach, which I believe is the best one to follow. It assumes that no one knows what ultimate reality is or even whether an "ultimate reality" exists. It starts from all the planetary, galactic, and cosmic experience and knowledge human beings have collectively gathered and tries to infer/extrapolate/induce from it what may or may not lie outside that experience and knowledge. It never claims to know anything ultimately or absolutely and in this sense reflects a radically agnostic, tentative mindset. All it can do is make a case for this or that worldview on the basis of the best available evidence.
Though I've already explained and defended speculative philosophy in a number of previous posts, I want to return to it here because of a book I've just read by Roland Omnes titled Quantum Philosophy (Princeton, 1999). Omnes, a nuclear physicist, argues that quantum theory was teased out of nature not by the intuitive empiricism of traditional philosophy and science but instead by a mathematical logic so arcane and difficult that few human beings understand it. He says the formalism of this math has revealed an alien reality beneath the apparent reality of daily life. From now on, philosophy must start from this baffling microworld of subatomic particles and work its way backward to the macroworld of planets, stars, and galaxies that humanity instinctively intuits.
The key disjunct between the two worlds, Omnes says, is the unpredictability of microphysics versus the predictability of macrophysics. You can't simultaneously measure the position and momentum of subatomic particles because such particles are governed by wave phase functions that produce both wave and particle effects. Though electrons, for example, have mass, they occupy slots around atomic nuclei according to wave phase laws and hence only move in so-called quantum leaps among energy levels. The consequence is that the mathematical relationship between cause and effect on the micro level is overwhelmingly probabilistic, on the macro overwhelmingly deterministic.
In other words, the abstract formalism of modern math has uncovered a stunning and unsuspected truth about physical nature that, absent the formalism, would have remained unknown to science and philosophy. Omnes further argues that we must find in quantum indeterminacy our philosophical justification for the intuitive, common-sense grasp of the more predictable macro reality we're born into. We must base our philosophy of empirical reality on a more fundamental quantum reality. He does this by invoking a physical process he calls decoherence.
Decoherence occurs whenever all the wave phases of the innumerable subatomic particles comprising a macro object like a speck of dust "decohere" because of their tiny size and huge numbers, thereby giving the dust speck as a whole, unlike their own indeterminateness, a clearly definable position in spacetime. Dust, cats, and houses can't simultaneously be in different places like the electrons they're made of because the wave phases of all those electrons only function subatomically and in effect lose their wave phase ambiguities by decohering outside the atom.
All this sounds reasonable to me. But other aspects of Omnes' argument are flawed. First of all, he claims that mathematical truths like 2 plus 2 equals 4 or e equals mc squared are independent of nature and exist in some kind of transcendent realm of pure logic. The claim is routinely denied by most mathematicians, largely because it wraps math in mysterious, unworldly clothing unlike that of other practical human enterprises like science or technology.
Second, though justified in stressing math's abstract logicalness, Omnes goes awry, I think, in arguing that the discovery through modern math of a quantum-level reality unsuspected by scientists and philosophers before 1900 demands a redefinition of philosophy itself. From its origins in ancient Greece, speculative philosophy of the kind I champion has always tried to make the best sense it can of the mysterious realities human beings find themselves in the middle of. The classical materialists, who in my view were on the right track (and were the earliest Western philosophers), speculated that ultimate reality consisted of randomly colliding particles they called atoms. They were challenged by the Platonists, who speculated instead that ultimate reality was a transcendental power of pure thought that realized itself only disappointingly in physical matter.
These two great early hunches have dominated Western philosophy ever since. They're termed monistic because they assume that ultimate reality consists of a single basic component, either absolute matter or absolute idea. Dualism, the compromise between them introduced by Aristotle and subsequently adopted by Christian philosophers, speculates that the essence of God is an infinitely superior, immaterial, and creative power to think that brought the infinitely inferior reality of material nature into being and is absolutely unlike it. These two kinds of reality, divine thought and physical matter, will remain diametrical opposites until God chooses to change them in some way.
Both monistic philosophies, and the dualistic compromise between them, are completely speculative in my sense of the term. They use the best reasoning and evidence they can muster to support their hunches concerning ultimate reality. Materialism has an advantage here in welcoming all scientific and technological proof into its worldview without hesitation. Idealism, on the other hand, has always been hamstrung by its refusal to credit the empiricism underlying science and technology. Its doctrine of transcendental ideation, for instance, was based on the assumption that human cognition was explicable only as a supernatural gift. Natural process, the idealists assumed, could not account for it. But we now know that brains are no more supernatural than fungi.
Christian dualism has weathered such questioning better, mainly because its worldview makes room for science. As long as you confine yourself to empirical evidence, you can investigate every natural process to your heart's content. Where you must stop is with divine truth, defined in all mainstream Christian sects, more or less, as biblical revelation. In this realm, traditionally known as Faith as opposed to Reason, you don't speculate or ask questions. You bow your head and believe.
Initially, I suspect, this religious impulse may have been akin to speculative philosophy. Many prehistoric religions tracked the movements of the sun, moon, and stars closely. Back then, the hunch that celestial objects were divine may have been fundamentally speculative. Those things in the sky, so real yet so mysterious, were explicable as products of some kind of unearthly power. From their own ability to make tools and shelters, primitive men and women may have inferred/induced/extrapolated a corresponding ability in superhuman beings to make stars and planets. The available evidence, that is, may have seemed to them to justify such a speculation.
But religion quickly lost whatever original speculativeness it may have had to dogmatism and zeal. Reasonable inferences about what ultimate reality might be gave way to blind faith in what it infallibly was. In Christian culture, speculative philosophy gradually shriveled into the linguistic nitpicking that today dominates academic philosophy, where ultimate reality is considered both irrelevant in itself and harmful to career advancement. Even thoughtful and well-informed scientists like Omnes have been conditioned to think they're philosophizing non-speculatively when in fact they are not.
In the thirteenth of Quantum Philosophy's sixteen chapters, Omnes announces he's a Christian. Though he does this in a careful, non-polemical, science-friendly way, he also insists on the need for belief in what he calls the "sacred," which, he says, "is everywhere in the universe and nothing is completely profane." He follows this fairly transparent dualism up with the crystal-clear dualism of the final four pages of his book.
There he sets up an extraordinary parallel between "Reality" and "Science" on the one hand and "Logos" and "Mathematics and Logic" on the other. Just as "Reality," or physical nature, caused "Science" to emerge, he argues, so "Logos," or divine order, caused "Mathematics and Logic" to emerge. The speculative dualism of all this is obvious in his conclusion that "everything becomes clear if Logos is a consistent entity independent of Reality" -- if, that is, divine thought is assumed to be absolutely different from and superior to physical nature, which is the key speculative assumption philosophical dualists have always made.
Omnes doesn't seem to understand that, far from discovering some great new philosophical truth at the heart of things, he has simply done what I and all speculative philosophers have always done: -- extrapolate, infer, and induce from what we do know tentative explanations of what we do not and probably cannot know. Quantum Philosophy is a fine effort to update speculative dualism, but its claim to do more than that is hollow. Philosophy at its best is always speculative.