> And it's a far cry from "there's no proof of x" to "x is invalid".

Oh this is undoubtedly true, and my argument was limited to the statement that the most common argument for physicalism is invalid. I was not launching an attack on physicalism itself.

> No metaphysical stance can be proved.

That's an interesting metaphysical stance, but again, I'm not trying to prove any metaphysics, just pointing out the main weakness that I see in the physicalist argument. I'm pointing out that any pro-physicalist argument that is a variant of "neuroscience says X" is invalid for the reason I gave: by limiting your scope to S, you can say nothing about anything outside S. This is true regardless of whether there is actually anything outside S, so there is no assumption in my argument that physicalism is wrong.

One argument against physicalism is that if thought or knowledge can be reduced to particles bouncing around, then there is no thought or knowledge. My knowledge that 2+2=4 is about something other than, or different from, the particles in my brain. Knowledge is about the content of the mind, which is different from the associated physical state of the brain. If content is neurons, then content as something my mind considers doesn't exist. If my thought "2+2=4" just is a bunch of particles in my brain doing stuff, then my belief that my thought is true is not even wrong, as the saying goes: just absurd.

I'm no Cartesian dualist though -- the interaction problem is just one problem with his dualism. I think Aristotle and Aquinas basically got the picture of reality right, and their metaphysics can shed yuuuuge amounts of light on the mind-body problem but obviously that's a grossly unfashionable worldview these days :-)

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jibal 6 days ago | parent [-]

> I'm not trying to prove any metaphysics

You attacked physicalism for not being proven.

I disagree with your arguments and I think they are hopelessly confused. Since our views are conceptually incommensurate, there's no point in continuing.

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geye1234 6 days ago | parent [-]

I'm afraid the physicalist position is absolutely impossible. When I think about something, I'm thinking about something different from the brain state that represents it. There is nothing difficult or subtle about this: if I think about a tiger, I am not thinking about a brain state that is associated therewith.

The physicalist position wants to reduce the mental to the physical. My thought cannot be reduced from the mental to the physical, because my thought is about a tiger, and a tiger cannot be reduced to a brain state.

If physicalism is true, I can't really be thinking about a tiger, because the tiger in my thought has no physical existence-as-a-tiger, and therefore can't have any existence-as-a-tiger at all. But then I'm not really thinking about a tiger. And the same applies to all our thoughts: physicalism would imply that all our thoughts are delusional, and not about reality at all. A non-physicalist view allows my thought to be actually about a tiger, without that tiger-thought having physical existence.

(Note that I have no problem with the view that the mental and the physical co-incide, or have some kind of causal relationship -- this is obviously true -- only with the view that the mental is reducible to the physical.)

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GoblinSlayer 5 days ago | parent [-]

You aren't even wrong, thoughts are fantasy indeed, and imaginary tiger doesn't have a literal physical existence, because it's, well, imaginary, it only has existence in imagination. And this theory matches observation.

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geye1234 5 days ago | parent [-]

Here's what I just posted to the other person. Perhaps you can tell me where I'm going wrong, because it seems to me that physicalism is impossible.

The UMD paper you link to elsewhere describes the central proposition of mind-brain identity physicalism as follows:

> a pain or a thought is (is identical with) some state of the brain or central nervous system

> ‘pain’ doesn’t mean ‘such-and-such a stimulation of the neural fibers’... yet, for all that, the two terms in fact refer to the very same thing." [emphasis in original]

(If you search for this second sentence and see it in context, you will see that substituting 'thought' for 'pain' is a fair reflection of the document's position.)

But this is problematic. Consider the following:

1. Thoughts are, at least sometimes, about reality.

2. My thought in some way refers to the object of that thought. Otherwise, I am not thinking about the thing I purport to be thinking about, and (1) is false.

3. That reference is not limited to my subjective, conscious experience of that thought, but is an inherent property of the thought itself. Otherwise, again, (1) is false.

4. Physicalism says the word "thought" and the phrase "a particular stimulation of neural fibers" refer to the same thing (from document above).

5. "A particular stimulation of neural fibers" does not refer to any object outside itself. Suppose I'm thinking about a tiger. You cannot analyze a neural state with a brain scan and find a reference to a tiger. You will see a bunch of chemical and electrical states, nothing more. You will not see the object of the thought.

6. But a thought must refer to its object, given 2 and 3. So "thought" and "particular stimulation of neural fibers" cannot refer to the same thing. (I will grant, and it is my position, that the latter is part of the former, but physicalism identifies the two.)

This seems to imply physicalism is false.

What step am I going wrong on?

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GoblinSlayer 5 days ago | parent [-]

5. If the reference exists, it doesn't disappear if you don't see it. You should see better. Reference has a corresponding material fact too.

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geye1234 4 days ago | parent [-]

Point 5 is sound, and it's actually impossible for a configuration of neural fibers to refer to something outside itself (and therefore, if physicalism is true and thought = neural fibers, it's impossible for a thought to refer to something outside itself, which would falsify point 2). Here's why:

The reference can't exist in the thought if "thought" and "a particular stimulation of neural fibers" refer to the same thing. There is no reference in the fibers. You can't "encode" a reference to something else in the physical brain (or any part of the body).

This is because a reference must in some way refer to its object (obviously). But a reference can only be referred to its object by something else. The word "tiger", or a picture of a tiger, refer to an actual tiger only when there is a mind to give them that meaning. But "a particular stimulation of neural fibers" cannot refer to any object, because there is nothing that can give it that meaning. A word or a picture or anything extra-mental can be given meaning by a mind, but when we are talking about the mind itself, this is impossible.

	▲	GoblinSlayer 3 days ago \| parent [-]
		If meaning is given, it's a structural property of mind and is encoded in brain like any other structural property.