When I put up my previous post about physicalism (4/9/2013), I described it as: “… the idea, roughly speaking, that everything can be explained by physics and that the scriptures thereof can written down in mathematics.”

This was quite brief. A bit like describing an important character in a novel as “six feet tall and wearing chain mail” and then saying nothing more of him for the rest of the story. We usually want to know more about the lead character. We would like to know things like whether he has blue eyes or brown. Is he a surly individual or light-hearted? Does he decapitate the waitress when she puts skim milk in his coffee instead of half-and-half? And so forth.

So let us sit down and have tea (figuratively speaking) with physicalism and make his—or its—acquaintance.

Of course, since this is an imaginary tea, the traits I ascribe to our distinguished guest may be nothing more than my individual fantasy. And I may miss traits that my readers feel to be vital. Nevertheless, physicalism is so thoroughly at home in our collective conscious (and subconscious) that I am hopeful most of my readers will say, “Yes, that’s him, that’s the culprit! ”

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1. A basic assumption of physicalism is that there is a reality (perhaps hidden) that we can probe by the use of our senses, reason, and mathematics. That is, there is a basic structure to the universe, a story we can tell about it, that can be brought to light by use of these instruments (senses, reason, and mathematics).

2. It also tends to be assumed that this structure runs upward from basic, fundamental things to the more interesting ones. This is, if you will, reductionism.

That is, quarks and fields get together to make electrons and protons and atoms, and these join to make molecules, and eventually we work our way to stars and brains and galaxies. There is a chain of explanation and causation (perhaps in a probabilistic, nondeterministic way) that runs from simple to complex, and the description of this chain is provided by mathematics. Things such as cats, roses, and the way our heart flutters at a baby’s smile are simply the working out of that chain. But it is the atoms and laws of physics that are the basic reality.

3. A third assumption is that whatever we can know about the universe can be found only by the aforementioned instruments—our senses, reason, and mathematics. There is no other way to knowledge. It seems to me that this should be called the Imperial Assumption.

4. An assumption which is closely tied up with the faith in mathematics is that the only things we can really know are measurements. This is the only way in which we have direct contact with nature.

To be sure, our first response may be that this is nonsense, that there are many things in our direct experience that have nothing to do with measurement. We may, for example, think we really know the look of red in a blooming rose. The sensation of red is clear and immediate in our minds; it has nothing to do with rulers or timers.

However a closer examination of the process leads us to see that the cells of our eyes are responding to photons of a certain frequency. But this only happens if a sufficient number of the proper photons turn up. Assuming they do, this results in a signal that is sent to our brains. This in turn is processed and lights up other brain cells in a way that causes us to say, “Red! ”

“You see! ” I imagine physicalism crowing triumphantly. “Everything is measurements! ”

Incidentally, this particular faith tends to be accompanied by a feeling that a measurement made by some sort of instrument—a gadget—is more real than an impression that registers in a human mind. (“I don’t care if you do think the milk smells funny. We’ve run the lab tests and it meets all the FDA standards. Drink it! ”)

5. Another basic assumption of physicalism (or perhaps it should be regarded as a deduction from the previous assumptions) is that the underlying structure of reality does not depend on us. Planck’s constant is the same for Daleks as for humans. More broadly, the assumption is that the laws of the universe do not depend on intention, desire, or consciousness. They are independent of anything that looks like mind or spirit. They just are.

A classic anecdote illustrates this idea: One of the most famous works of the French mathematician Laplace was Mécanique céleste, a volume meant to illuminate the workings of the solar system. When Napoleon took the mathematician to task for failing to mention God, Laplace replied, “Sire, I had no need of that hypothesis.”

Another noteworthy expression of this sentiment is the short story The Cold Equations by Tom Godwin. The point it makes is very clear: The universe does not care.

6. It seems a natural consequence of all the above that there is no room for God in the universe nor for gods or half-gods or spirits. Atheism is a comfortable fit with physicalism.

7. But the next thing physicalism may lead us to discard is consciousness.

If we look at the electrons and protons and oscillating probability amplitudes that presumably make up reality, it is hard to spot anything that looks like consciousness. To be sure, we can claim that consciousness is just something like a standing wave or algorithm generated by these more elementary entities hooked up to form a brain. And if we believe in physicalism, then at some point we may even be able to write down equations describing consciousness!

But if we compare the sensation we have of our individual consciousness with a list of equations, we may well have a bewildered feeling that we see no connection between the two. To say that the equations describe the bright point of awareness which is our consciousness begins to look uncomfortably like an act of faith. Indeed there are philosophers and scientists who use the words “consciousness” and “illusion” in the same sentence a great deal of the time.

The unpleasant possibility arises that not only does physicalism have no room for God, it has none for Man either.

8. In line with the points above, it is easy to feel there something “contradictory” about physicalism. Now I do not mean “contradictory” in the sense of a logical contradiction. I have in mind something more like an emotional or psychological contradiction. Perhaps it is more aptly called a “dissonance.”

This is sharply brought out in Bertrand Russell’s essay A Free Man’s Worship . On the one hand, Russell gives full weight to the idea that the universe does indeed not care: “Blind to good and evil, reckless of destruction, omnipotent matter rolls on its relentless way.” Yet the heart of the essay is a resounding cry to defiance of this conclusion, a call to rise above the fact that we exist in a universe that will not only destroy us but that is, at base, meaningless. There is, in this cry, something of the spirit of the gods of Norse legend facing Ragnarok, the Twilight of the Gods, the end of the world.

Yet though there is something magnificent in Russell’s stand, how can it—on his own assumption of the nature of reality—amount to anything more than a puppet twitching through the motions of an act in which it pretends to have no strings? How can we believe in a universe lacking in significance yet claim significance for our own lives? Or even for the belief just expressed?

To put our “dissonance” in different words—can it be that to dwell on the Mount of Truth, we must live in air so thin that we cannot breathe it?

9. We come now to the end of our interview. Let us, in parting, look at why it might be that physicalism is an idea adopted by so many with scarcely a question.

We are taught from early on that science is an important source of profound truths. Now when we think of the great triumphs of science, we usually have in mind the accomplishments of very particular sciences. For example, relativity theory and quantum mechanics in physics. Or genetics and Darwinian evolution in biology.

All these disciplines are “sciences,” so we easily assume there is something called science (or, better yet, Science, with a capital S) of which physics, chemistry, astronomy, etc. are all examples. Now physicalism is not the same as physics; one is a philosophy, an outlook on the nature of reality, while the other is a particular and limited discipline. Nor is physicalism the same as chemistry or astronomy or biology or any other science But I suspect that for most people the word science is almost synonymous with the idea physicalism.

Now if this is so, then it is easily seen that the impressive array of scientific discoveries of the last few centuries stands as a “proof” of the correctness of physicalism. We deduce this via the popular and widely used logical principle, “I have such a marvelous hammer that surely every problem must be a nail! ”

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So now the tea cups have been emptied and turned over and the interview ended. I hope you found it of interest.

There may be traits of physicalism that I overlooked. Or that I distorted. Or some that I discussed that you feel should really not be on the list. If so, feel free to conduct your own interview and correct the shortcomings of this one.