Part of an ongoing, possibly endless, conversation. My apologies to those whose patience with this is not superhuman.

A reader of the philosophical materialist persuasion named Andreassen offers me the following axiom, which I call the panphysicalist axiom:

All atomic motions without exception, including those in the bodies of free-willed beings, are exactly described by the laws of physics.

I asked him, if this axiom is true, how he knows it to be true? Explained the question in the following terms:

Specifically I was attempting to discover from you whether the axiom (1) applies to this and every logically conceivable version of the cosmos (2) happens to apply to this cosmos but conceivably might not (3) applies only to local conditions within the cosmos, such as at or near the earth’s surface.

His answer:

Your second option is true: Materialism is a conditional universal.

My reply is below

If materialism were a universal conditional, like the speed of light, then in order to show that we are in the panphysicalist universe rather than in the universe described by Descartes, or Aquinas, or Bishop Berkley, or Plato, or Aristotle, there would have to be an experiment, a measurement, akin to that measurement we take to determine what the speed of light is.

What is that measurement?

If there is no measurement, then I humbly suggest that you have miscategorized your answer. You are not speaking of a conditional universal.

The speed of light is a conditional because, for all we know, in the conditions of the early universe or the end of the universe, the speed of light might change. It may be growing slower as the universe ages. It is conditional because it depends on conditions.

But your argument is that a non-panphysical universe is unimaginable, too complex to be a good theory. This sounds like you are trying to say that it is based on a fundamental axiom, first that reality must be logically consistent, and second that reality must be elegant, that is, that the simpler explanation is the truer one.

Do you believe reality must be logically consistent?