Thursday, September 22, 2016

An argument against pain being identical with c-fibre firing

Here's the slide I promised to make available from yesterday's talk. For X and Y substitute eg pain and c-fibre firing or red and reflects light of wavelength x. Note the argument does not work for heat and molecular motion, or water and H2O, because premise (iv) is then false. But is the argument cogent for pain and c-fibre firing?

Notice that, unusually, this conceivability argument turns not on what is conceivable (e.g. pain without c-fibre firing, zombies, etc.), but on what is inconceivable.

Why suppose (iv) is true for pain? Because it appears to be part of the concept of pain that one cannot be mistaken about whether one is experiencing it (at least in core cases). Hence there is a conceptual obstacle to imagining fool's pain (fool's pain = feels like pain but isn't really pain). But if pain were c-fibre firing, no such conceptual obstacle would exist (or indeed would exist if pain was potentially identifiable with any physical property at all; hence this conceptual truth about pain (that fool's pain is impossible) entails pain cannot be identified with any physical property at all).

This is the argument I attribute to Kripke in his Naming and Necessity. Notice it differs from that commonly attributed to Kripke by eg Brian Loar. As applied to colour, the above argument also seems to me to be presented by Colin McGinn in his The Subjective View as an argument against identifying red with a physical property such as reflecting a particular wavelength of light, and as part of his a priori, conceptual case for saying colour is a secondary quality.

For more see my paper Loar's Defence of Physicalism.



10 comments:

DanStenning said...

Here is my best stab at why this argument fails:
The brain is an elaborate network of what could be called metaphorically - "conclusion-generators" which feed, modify, affect and interact with other conclusion generators.
Certain brain-conclusion-events appear to the experiencer as a quale. A quale is the result - and results from certain brain-conclusions. A quale can be for example RED or PAIN. C-Fibre firings are NOT necessary for a pain-quale to be generated since a conclusion-event can occur simply because the appropriate conclusion generators were fired But NOT because of any C fibres having fired - ( as in phantom pain, seizures, dreams, hallucinations etc ).
-
The quale itself in nearly all cases is normally resulting from a conclusion event related to some external or internal physical event. RED represents an external light source roughly comprising certain wavelengths typically classified as RED. The qualia-conclusion-event is however at heart a brain phenomenon -and false conclusions can be fired off for all manner of reasons without an external source. The experience will be the same.
-
Although naive realism normally applies in daily life - a conclusion can occur falsely. The experience of the conclusion will always be real to the experiencer either way. But without the appropriate conclusion circuits firing there will be NO experience.
-
Putting QUALE and THE RESULT OF A BRAIN CONCLUSION into (i) and substituting "gets experienced as" instead of "appears as" yields:

" (i) Something that gets experienced as A QUALE but isn’t THE RESULT OF A BRAIN CONCLUSION is conceivable "

But this premise is wrong. False. No quale will ever occur if the relevant brain conclusion event of the appropriate kind tied to the quale has not occurred. I think neuroscience backs this up significantly.
-
So the problem with this argument is that it simply does reflect how the brain is operating. And the conceivability word here is prone to attack on many levels already discussed in many other phil papers. For example can one conceive of time travel ? maybe - is TT physically possible ? one can conceive anything but empiricism and science - or at the least - theory and mathematical calculations are needed to establish possibility. Conceivability needs to be tied down rigorously by logic maths and science. Otherwise it is merely imaginability -which is a poor arbiter or yardstick for "possibility.

Muslim Salik said...

Interesting paper Dr Law!

Playing devil's advocate here - Whatever pain is, it is identical to some property, whether physical or non-physical. Suppose it is non-physical, then couldn't we run the same conceivability argument? For example, perhaps pain is identical to the (non-physical) mind being in non-physical state xyz. Surely it is conceivable that I am in pain, but that my non-physical mind is not in xyz. However, given that pain = non-physical state xyz, then it is possible that it seems that I am in pain but am not, which is impossible.

Thanks!

Anonymous said...

Hi Dr Law,
Isn't it possible to run the same argument against the claim that pain is not physical? Conceptually, pain is different from, for example, a certain non-physical state of the non-physical mind, ergo, pain isnt a state of the non-physical mind. What would you say to that?

Stephen Law said...

Nice point. Yes, it should block any identity theory (ie where expressed by an identity claim involving two rigid designators). But 'pain is a state of the non-physical mind' is not an identity claim, is it? That's the 'is' of predication, isn't it? In which case no obstacle to it being true. But the argument will block essentially identifying pain with anything at all. Which is fine, I think?

Stephen Law said...

...so there's no problem saying pain is a non-physical state of the mind. There's just a problem with identifying it with some *other* non-physical state of the mind.

Stephen Law said...

And, incidentally, it can be identical with itself of course (because that identity claim is not epistemically contingent/conceivably false).

Muslim Salik said...

What if we reformulate the argument in terms of essential properties.

1. Pain has the property of being non-physical, therefore being non-physical is a necessary condition of pain.
2. I can conceive of the appearance of pain in the absence of anything non-physical
3. Therefore I can conceive of the appearance of pain in the absence of pain.
4. (3) is impossible, therefore (1) is false
5. Therefore pain is physical.

What do you think?

Philolinguist said...

It would be helpful to de-conflate the concept of 'pain'. There's 1) the subjective sensation of pain, 2) one's belief that one is in pain, and 3) pain behavior. Of these, only 2) is inarguably a sufficient condition for being in pain. There is no knock-down argument that 1) can happen without 2), because 1) is a first-person experience which, at least in my experience, always coincides with 2).

To argue that someone (e.g. a human baby or a cat) can have 1) without 2) is to infer that conclusion from 3), and that is not a logically valid inference. So it is logically possible that pain is nothing over and above the belief that one is in pain. Our natural response to someone else's pain does not obviously invalidate the foregoing conclusion. Our decision to help someone in pain is not premised on a complex belief like "They are showing pain behavior, therefore must be experiencing what I experience as 'pain'". Otherwise, non-human animals would be unlikely to help others who are in pain, because such animals can't form complex beliefs. But some non-human animals do respond altruistically to the pain of others. Whatever is involved in that response, it isn't premised on a belief that someone else is having 1).

Can a purely physical thing (say, a robot) believe they are in pain? Much depends on the story behind it. For example, if my best friend was gradually replaced piece-by-piece with electronics, until there was nothing organic left (but he looks and behaves the same), at what point would I cease to believe he feels pain? Quite plausibly, never. On the other hand, if I saw a robot assembled from scratch, it is unlikely I would believe it feels pain even if it looked and behaved perfectly human. These scenarios illustrate that empathy is a complex socio-psychological phenomenon that isn't entirely transparent to us, and could possibly evolve to a point where we end up empathizing with robots. Which begs the question, could we be robots, and our 'inner lives' are a story we tell ourselves?

In which case, the story would be integral to what makes us 'human'. In other words, everything of value is in the human story, and everything outside that story is beside the point, including the origin of the story itself. It doesn't matter if we're robots. The story, in other words, has a life of its own. In which case, we're not robots.

Philolinguist said...

Some may be puzzled by my remark above that only 2) is inarguably a sufficient condition for being in pain. The reason I say that is because there is no knock-down argument that 1) is anything other than 2), in which case the only real alternatives above are between 2) and 3), of which only 2) is incontrovertibly a sufficient condition for being in pain.

How can pain be equated with the mere belief that one is in pain? You can hypnotize someone into believing they are in pain, and they will show the same brain activity as someone in 'real' pain:

http://www.nature.com/nrn/journal/v14/n8/fig_tab/nrn3538_F3.html

Furthermore, in our subjective experience, 1) cannot happen without 2). BTW, the same is true of all our 'inner life', if you replace pain with smelling coffee, seeing red or touching silk. Some may object, what about non-human animals, surely they don't believe they're in pain, they just have the pain? But why can't a cat believe it's in pain? Is it too stupid? It may not be saying "I'm in pain" to itself, but neither do I when I'm in pain.

If our 'inner life' is really just a matter of believing we're 'in pain', or 'tasting coffee', etc, then it is logically possible that beliefs are all there is. That would be a form of Idealism. Some may object, what about qualia? I'll have to refer the reader to Wittgenstein's 'private language argument' and the literature on that.

Muslim Salik said...

no comments on my revised counter argument Dr Law?