Exhibit a
> Nagel begins by assuming that "conscious experience is a widespread phenomenon" present in many animals (particularly mammals), even though it is "difficult to say [...] what provides evidence of it".
Physicalism is an ontological assertion that is almost certainly true, and is adhered to by nearly all scientists and most philosophers of mind. Solipsism is an ontological assertion that could only possibly be true for one person, and is generally dismissed. They are at opposite ends of the plausibility scale.
It's like describing the inside of a house in very great detail, and then using this to argue that there's nothing outside the house. The method is explicitly limiting its scope to the inside of the house, so can say nothing about what's outside, for or against. Same with physicalism: most arguments in its favor limit their method to looking at the physical, so in practice say nothing about whether this is all there is.
> Same with physicalism: most arguments in its favor limit their method to looking at the physical, so in practice say nothing about whether this is all there is.
This is simply wrong ... there are very strong arguments that, when we're looking at mental events, we are looking at the physical. To say that arguments for physicalism are limited to looking at the physical is a circular argument that presupposes that physicalism is wrong. The arguments for physicalism absolutely are not based at looking at a limited set of things, they are logical arguments that there's no way to escape being physical ... certainly Descartes' dualism is long dead due to the interaction problem -- mental states must be physical in order to be acted upon or act upon the physical. The alternatives are ad hoc nonsense like Chalmers' "bridging laws" that posit that there's a mental world that is kept in tight sync with the physical world by these "bridging laws" that have no description or explanation or reason to believe exist.
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 :-)
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.
I don't believe any of that to be true, but I think that's kind of the point of that argument. I do think we start from that Cartesian starting place, but once we know enough about the external world to know that we're a part of it, and can explain our mind in terms of it, it effectively shifts the foundation, so that our mental states are grounded in empirical reality rather than the other way around.
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.)
> a pain or a thought is (is identical with) some state of the brain or central nervous system
or
> ‘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?
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
or
> ‘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?
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.
> Physicalism says the word "thought" and the phrase "a particular stimulation of neural fibers" refer to the same thing (from document above)
Here is what it actually says:
> The identity-thesis is a version of physicalism: it holds that all mental states and events are in fact physical states and events. But it is not, of course, a thesis about meaning: it does not claim that words such as ‘pain’ and ‘after-image’ may be analyzed or defined in terms of descriptions of brain-processes. (That would be absurd.) Rather, it is an empirical thesis about the things in the world to which our words refer: it holds that the ways of thinking represented by our terms for conscious states, and the ways of thinking represented by some of our terms for brain-states, are in fact different ways of thinking of the very same (physical) states and events. So ‘pain’ doesn’t mean ‘such-and-such a stimulation of the neural fibers’ (just as ‘lightning’ doesn’t mean ‘such-and-such a discharge of electricity’); yet, for all that, the two terms in fact refer to the very same thing.
And yet the sort of analysis that points out as absurd is exactly the sort of analysis you are attempting.
> 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.
Says who? Of course we don't currently don't have such technology, but at some time in the future we may be able to analyze a brain scan and determine that the subject is thinking of a tiger. (This may well turn out not to be feasible if only token-identity holds but not type-identity ... thoughts about similar things need not correspond to similar brain states.)
Saying that we only see a bunch of chemical and electrical states is the most absurd naive reductivist denial of inference possible. When we look at a spectrogram, all we see is colored lines, yet we are able to infer what substances produced them. When we look at an oscilloscope, we will see a bunch of curves. etc. Or take the examples at the beginning of the paper ... "a particular cloud is, as a matter of fact, a great many water droplets suspended close together in the atmosphere; and just as a flash of lightning is, as a matter of fact, a certain sort of discharge of electrical energy" -- these are different levels and frameworks of description. Look at a photograph or a computer screen up close and you will see pixels or chemical arrangements. To say that you will see "nothing more" is to deny the entirety of science and rational thought. One can just as well talk about windows, titles, bar charts, this comment on a computer screen as referring to things but the pixel states of the screens that are coincident with them don't and thereby foolishly, absurdly, think that one has defeated physicalism
Enough with the terrible arguments and shoddy thinking. You're welcome to them ... I reject them.
Over and out.
It is not a question of "different levels and frameworks" of description in this case, or at least not solely. The examples of clouds and lightning given in the paper are not valid parallels (I know the paper doesn't offer them as parallels, but your comment did), because they do not need relations with other things to be water droplets and discharges of electricity. But a word needs a relation with something else (its referent) to be a word, otherwise it is just meaningless squiggles, sounds or pixels. And the word does not have this relation in and of itself: only a mind can give it this relation.
(You can take relation and reference as largely synonymous for the purposes of this comment.)
You can analyze the squiggles as closely as you like, but you will still not find any relation to a tiger, unless you have something else (a mind) giving it that relation. And again, the same is true for the other examples you give. Extrinsic relations exist between word and thing or oscilliscope and wave, but not intrinsic ones.
In the same way, the brain's state when it thinks of a tiger is, in and of itself, a bunch of chemical and electric states that bear no intrisic relation to a tiger. No amount of analysis of the brain's state will change this. As I stated somewhere else, a tiger and a brain state, like a tiger and the word "tiger", are two entirely different things, and are not intrinsically related to each other. You can analyze either the tiger or the brain state with whatever sophisticated technology you want, but that will not change this fact. Analyzing a bunch of squiggles will produce information about the ink, but not information about a tiger: you are still looking at ink. Analyzing chemical and electric states will produce interesting and very valuable information about the brain, but not information about a tiger: you are still looking at chemical and electric states. No amount of searching will find intrinsic relation between brain-state and thing. [I think this is also a good argument against Cartesian dualism, but that's beside the point right now.]
The relation between thought and its object must be intrinsic (assuming our thoughts are about, or can be about, reality). It cannot be extrinsic like a word or oscilliscope, because our thoughts are not given their meaning by something outside our minds. (I assume we agree on this last point after "because", and it doesn't need arguing.) Our thoughts' relations to their objects must be intrinsic to the thoughts. But they can't be intrinsic if our thoughts are our brain states, for the reason just given.
(The UMD paper responds to this objection in section 3.8: briefly, my response is that we might get the illusion of intentionality in a physical system like a computer, but no more than that.)