On Rasmussen's "Against non-reductive physicalism"

After presenting his thesis in the first section, that mental properties are not physical properties, nor are they grounded in physical properties, he carefully defines what he means by physical properties. Broadly, a physical property is something that can be measured. But nowhere does he define what a mental property is. This will turn out to be important, since mental property could mean something not physical that we think about, or it could mean how we think about something. I will use mental property for something non-physical that we think about and mental state to refer to the act of thinking, whether thinking about physical or mental properties.

It should be without controversy that there are more non-physical things than physical things. By some estimates there are 10^80 atoms in the universe. There are an unlimited number of numbers. We can't measure all of those numbers, since we can't put them in one-to-one correspondence with the "stuff" of the universe.

The first thing to note is that if the number of things argues against the physicality of mental states, then mental properties aren't needed, because there are more atoms in the universe than there are in the brain. If the sheer number of things argues against physical mental states then this would be sufficient to prove the claim. But as anyone who plays the piano knows, 88 keys can produce a conceptually infinite amount of music. And one need not postulate non-physicality to do so. Just hook a piano up to random number sources that vary the notes, tempo, and volume. The resulting music may not be melodious, but it will be unique.

Rasmussen presents a "construction principle" which states "for
any properties, the xs, there is a mental property of thinking that the xs are physical." Here the confusion between mental property and mental state happens. The argument sneaks in the desired conclusion. After all, if this principle were true, then the counting argument wouldn't be needed. Clearly, there is a mental state when I think "my HomePod is playing Cat Stevens". But whether that mental state is physical or immaterial is what has to be shown. By saying it's a mental property then the assertion is mental states are non-physical and the rest of the proof isn't necessary. It's just proof by assertion.

Rasmussen then gives what he calls "a principle of uniformity" which says, "The divide between any two mental properties is narrower than the divide between physicality and non-physicality." To demonstrate this difference between physical and non-physical, he gives the example of a tower of Lego blocks. His claim is that as Lego block is stacked on Lego block, that both the Lego tower, and the shape of the Lego tower, remains physical. He asserts, "if (say)
being a stack of n Lego blocks is a physical property, then clearly so is being a stack of n+1 Lego blocks, for any n." This is clearly false. A Lego tower of 10^90 pieces is non-physical. There aren't enough physical particles in the universe for constructing such a tower. Does the shape of the Lego tower remain physical? This is a more interesting question. A shape is a description of an arrangement of stuff. The shape of an imaginary rectangle and the shape of a physical rectangle are the same. Are descriptions physical or non-physical? To assert one or the other is to beg the question of the nature of mental states.

So we have a counting argument that isn't needed, a construction principle that begs the question, and a principle of uniformity that doesn't match experience.

Having failed to show that mental states are non-physical, in section 3 Rasmussen tries to show that mental states aren't grounded in physicality. The bulk of the proof is in his step B2: "if no member of M
PROPERTIES entails any other, then some mental properties lack a physical grounding." He turns the counting argument around to claim that there is a problem of too few physical grounds for mental states. This claim is easily dismissed. First, consider words. The estimated vocabulary of an average adult speaker of English is 35,000 words. There is plenty of storage in the human brain for this. But if we don't know a word, we go to the dictionary to get a new definition and place that definition in short term reusable storage. If we use it enough so that it goes into long term storage, we may forget something to make room for it.

In the case of "infinite" things, we think of them in terms of a short fixed description of behavior, so we don't need a lot of storage for infinite things. The computer statement

10 goto 10

is a short description of an endless process. We don't actually think of the entire infinite thing, but rather finite descriptions of the behavior behind the process. [1]

Rasmussen's proof fails because the claim that there needs to be a unique physical property for each mental state doesn't stand. Much of our physical memory is reusable and we have access to external storage (books, videos, other people). In fact, as I wrote in 2015, "man is the animal that uses external storage". [2]

Since the final sections 4 and 5 aren't supported by 1, 2, and 3, they will be skipped over.

[1] See "
Lazy Evaluation" for some ways to deal with infinite sequences with limited storage.
"Man is the Animal...". Almost seven years later, this statement is still unique to me. Don't know why. It's obvious "to the most casual observer."

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