Friday, 31 July 2015

Patricia Churchland vs. the Functionalists


 
Patricia Churchland has a problem with the fact that many functionalists have “ignored neuroscience”. Indeed they've also “rejected reductionism” (1986). However, I suspect that this is much less true today than it was when Churchland wrote this in 1986.

Not only do many functionalists ignore neuroscience, they also take some pride in doing so. Or, as Churchland surmises, functionalists may think that

the less known about the actual pumps and pulleys of the embodiment of mental life, the better, for the less there is to clutter up one's functionally oriented research” (1986).

I would say that the primary reason for this functionalist ignorance of all things neuroscientific is that functionalists believe that “computational (functional) psychology” can only then be seen as an “autonomous science”. They may believe that if neuroscience had the last word on these matters (or if it were all a question of reduction in the end), then such functionalists wouldn't really have any territory they could call their own.

Of course one can be this kind of functionalist and still be a physicalist. Though can functionalists also be reductionists? Yes, in principle; though primarily because of the multiple realizability argument (which is tackled later), that would rarely be the case. In principle a functionalist could also know lots of neuroscience and still not find his mind “cluttered up” (as Churchland puts it). Indeed he may know loads of neuroscience and argue that all the cognitive sciences should still be seen as autonomous.

According to Churchland, Zenon Pylyshyn puts the case for this neat division of labour. Thus:

i) “... cognitive scientists will figure out the functional/cognitive...”

ii) “... neuroscientists can untangle the underlying physical devices that instantiate the cognitive 'program'...” (1986)

At first glance it simply seems to be counter-productive to argue that these two departments should never interact (or clutter each other up). It depends, though, on whether that separation is complete or not. And Churchland herself says that it's “doubtful” that “anyone really holds that extreme version of the research ideology” (1986). Nonetheless, Churchland does go on to say that “certainly milder versions [of this approach] have won considerable sympathy”. And she too says that the “autonomy of psychology is the rationale” behind that.

Reductionism

Just as Churchland thinks it's a bad idea for functionalists or psychologists to ignore neuroscience, so she also thinks it's an equally bad idea for neuroscientists (or eliminative materialists) to ignore functionalism or psychology. She writes:

Neuroscientists would be silly to make a point of ignoring psychological data... just as psychologists would be silly to make a point of ignoring all neurobiological data.” (1994)

Indeed if pressed (or looking from the outside looking in) it would seem almost impossible for either neuroscientists to ignore psychology or for psychologists to ignore neuroscience. Though, when one looks at the history, one quickly sees that this was indeed the case. Perhaps the most obvious example was the “black box” position adopted by behaviourists from the 1920s to the 1960s. (This was the position in which the mind-brain was simply seen as a receptacle for stimulations or the locus of various inputs and outputs.)

Churchland continues by mollifying psychologists about that scareword - “reductionism”. She tells psychologists or functionalists not to worry. She says that by “reductionist research strategy” she

does not mean that there is something disreputable, unscientific or otherwise unsavoury about high-level descriptions or capacities per se.” (1994)

Churchland says something that may even surprise some philosophers. She argues that reductionism can exist side-by-side with what she calls “high-level descriptions or capacities”.

In any case, reduction is vitally important in many sciences and it comes up with many important results. Nonetheless, it doesn't follow from this that all forms of reductionism have no room for “higher-level descriptions”. Indeed E.O. Wilson put a similar point (though about another area) when he wrote:

Major science always deals with reduction and resynthesis of complex systems, across two or three levels of complexity at a step. For example, from quantum physics to the principles of atomic physics, thence reagent chemistry, macromolecular chemistry, molecular biology, and so on – comprising, in general, complexity and reduction, and reduction to resynthesis of complexity, in repeated sweeps.”

Churchland herself says that

research techniques reveal structural organisation at many strata: the biochemical level; then the level of the membrane, the single cell, and the circuit; and perhaps yet other levels, such as brain subsystems, brain systems, brain maps, and the whole central nervous system” (1989).

Nonetheless, E.O. Wilson is of course well aware that the “very word 'reductionism'” has a “sterile and invasive ring, like a scalpel or catheter”. He goes on to say that the

[c]ritics of science sometimes portray reductionism as an obsessional disorder, declining towards a terminal stage one writer recently dubbed 'reductive megalomania'” (1998).

Multiple Realisability

The main argument against reduction in the philosophy of mind is the multiple realisability argument, as first advanced by Hilary Putnam in 1967 in his 'The Nature of Mental States'.

Churchland tackles this subject and makes a distinction between type-type and token-token reductions. The gist of the argument is that just as various 'types' of mental function or state can be multiply realised, so can various types in physics. Basically, that doesn't make the reduction either problematic or unscientific.

Take the scientific type temperature. Churchland writes:

Notice that what was reduced [in thermodynamics] was not temperature tout court, but temperature of gas. The temperature of a gas is mean kinetic energy of the constituent molecules, but the temperature of a solid is something else again...” (1986)

Thus reduction in this and in other cases is domain-specific. Or as Churchland puts it:

The initial reduction in thermodynamics was relative to a certain domain of phenomena, to wit, gases...”

However, this domain-specificity, according to Churchland, still means that “it was a bona fide reduction for all that”. As a result, did it make thermodynamics a special science (as psychology, economics., etc. are seen as special sciences)? Not according to Churchland. She says that that thermodynamics isn't “independent and separate from physics”.

Does that means that the special sciences aren't “independent and separate from physics” either? Surely it does.

In fact Churchland deals with the case of psychological functionalism and multiple realisability herself. She says that

if human brains and electronic brains both enjoy a certain type of cognitive organisation, we may get two distinct domain-relative reductions” (1986).

Churchland concludes by saying that the “domain-relative” reductions just discussed aren't thereby “phony reductions or reductions manqué”. And it “certainly does not mean that psychology can justify [its] methodological isolation from neuroscience” (1986).

However, just to backtrack a little, it isn't correct to say that Churchland's examples are token-token reductions because, for example, the temperature of a gas (as opposed to that of a solid or of plasma) is still dealing in types. It's just a lower-level type of a higher-level type. That is, we have the lower-level type [the temperature of a gas] and the higher-level type [temperature]. Indeed there will even be subtypes within the type [temperatures of gases] which would include different kinds of gases (though they too would still be type-reductions, not token-reductions).

All this can clearly be distinguished from, say, the attempt to reduce a single person's mental state (qua token) to its physiological and physical reduction-base. Then again, mental types are also problematic, as we will now see.

Some philosophers (i.e., not psychologists or cognitive scientists) do say that such reductions are unscientific – at least the reductions of mental types or functions. This may all depend on whether mental functions can be distinguished form the category of mental states. That is, reductions of mental functions may be less problematic than reductions of mental states. After all, mental functions can be seen as abstracta; whereas that's not the case with all – or any - mental states.

For example, Jaegwon Kim's solution to all this seems to be old-style reductionism. Or at least he puts the reductionist position when he says that the “reductionist identifies pain with neural state N”. The question is whether or not pain can be seen functionally. And even if it isn't seen that way, is it still problematic from a scientific point of view?

Kim does argue that pain as a "scientific kind... must go” and that elimination or reduction is the answer. That's primarily because - in Kim's case at least - of the problems associated with what's just been discussed: the multiple realisability of mental kinds in many and various physical substrates.

This is what Kim himself writes on this subject:

.... the frank acknowledgement that MR [multiple realisability] leads to the conclusion that pain as a property or kind must go. Local reduction after all is reduction, and to be reduced is to be eliminated as an independent entity.” (1992)

Kim accepts that pain and mental states/qualities exist: it's just that he doesn't deem them to be scientific kinds or properties.

Functionalist Dualism: Biology & Brains Matter

It's ironic that many of the functionalists and cognitive scientists who accuse all and sundry of being “dualists” should themselves be categorised in this way.

For example, many call John Searle a dualist and he, in return, says that those who stress function and ignore biology are effectively creating a non-material Cartesian reality populated with functions or computations rather than with “ideas” or “thoughts”. Patricia Churchland, on the other hand, doesn't use the word “dualist”, though she does say the following:

Many philosophers who are materialists to the extent that they doubt the existence of soul-stuff nonetheless believe that psychology ought to be essentially autonomous from neuroscience, and that neuroscience will not contribute significantly to our understanding of perception, language use, thinking, problem solving, and (more generally) cognition.” (1989)

Put that way, it seems like an extreme position. Basically, how could materialists (when it comes to the mind) possibly ignore the brain? It's one thing to say that “psychology is distinct from neuroscience”: it's another thing to say that psychology is “autonomous from neuroscience” and that “neuroscience will not contribute significantly to our understanding” of cognition and whatnot. Sure, the division of labour idea is a good idea. Though to see the “autonomous” in “autonomous science” as being about complete and total independence is surely a bad idea. In fact it's almost like a physicist stressing the independence of physics from mathematics.

Churchland thinks that biology matters. In this, she has the support of many others.

For example, the Nobel laureate Gerald Edelman says that the mind

can only be understood from a biological standpoint, not through physics or computer science or other approaches that ignore the structure of the brain” (1996).

In addition, you perhaps wouldn't ordinarily see Patricia Churchland and John Searle as being bedfellows; though they are on this issue. So it's worth quoting a long passage from Searle which neatly sums up some of the problems with non-biological theories of mind. Searle writes:

I believe we are now at a point where we can address this problem as a biological problem [of consciousness] like any other. For decades research has been impeded by two mistaken views: first, that consciousness is just a special sort of computer program, a special software in the hardware of the brain; and second that consciousness was just a matter of information processing. The right sort of information processing -- or on some views any sort of information processing --- would be sufficient to guarantee consciousness..... it is important to remind ourselves how profoundly anti-biological these views are. On these views brains do not really matter. We just happen to be implemented in brains, but any hardware that could carry the program or process the information would do just as well. I believe, on the contrary, that understanding the nature of consciousness crucially requires understanding how brain processes cause and realize consciousness.. ” (1999)

In a sense, then, if one says that biology matters, one is also saying that functions aren't everything (though not that functions are nothing). Indeed Churchland takes this position to its logical conclusion when she more or less argues that in order to build an artificial brain one would not only need to replicate its functions, but also everything (physical) about it.

Here again she has the backup of Searle. He writes:

Perhaps when we understand how brains do that, we can build conscious artefacts using some nonbiological materials that duplicate, and not merely simulate, the causal powers that brains have. But first we need to understand how brains do it.”

Of course you can say that you can have an artificial mind without having an artificial brain. Though isn't that precisely this that many dispute (perhaps Churchland does too)?

In any case, to use Churchland's own words on this subject, she says that

it may be that if we had a complete cognitive neurobiology we would find that to build a computer with the same capacities as the human brain, we had to use as structural elements things that behaved very like neuron” (1986).

Churchland continues by saying that

the artificial units would have to have both action potentials and graded potentials, and a full repertoire of synaptic modifiability, dendritic growth, and so forth”.

It gets even less promising for functionalism when Churchland says that

for all we know now, to mimic nervous plasticity efficiently, we might have to mimic very closely even certain subcellular structures”.

Put that way, Churchland makes it sound as if an artificial mind (if not artificial intelligence) is still a pipe-dream.

Readers may also have noted that Churchland was only talking about the biology of neurons, not the biology of the brain as a whole. However, wouldn't the replication of the brain (as a whole) make this whole artificial-mind endeavour even more complex and difficult?

In any case, Churchland sums up this immense problem by saying that

we simply do not know at what level of organisation one can assume that the physical implementation can vary but the capacities will remain the same”.

That's an argument which says that it's wrong to accept the implementation-function “binary opposition” (to use a phrase from Derrida) in the first place. Though that's not to say - and Churchland doesn't say - that it's wrong to concentrate on functions or cognition generally. It's just wrong to completely ignore the “physical implementation”. Or, as Churchland says at the beginning of one paper, it's wrong to “ignore neuroscience” and focus entirely on function.

Churchland puts the icing on the cake herself by stressing function. Or, more correctly, she stresses the functional levels which are often ignored by functionalists.

Take the cell or neurone. Churchland writes that

even at the level of cellular research, one can view the cell as being the functional unit with a certain input-output profile, as having a specifiable dynamics, and as having a structural implementation in certain proteins and other subcellular structures” (1986).

Basically, what's being said here is that in many ways what happens at the macro level of the mind-brain (in terms of inputs and outputs) also has an analogue at the cellular level. In other words, functionalists are concentrating on the higher levels at the expense of the lower levels.

Another way of putting this is to say what Churchland herself says: that neuroscientists aren't ignoring functions at all. They are, instead, tackling biological functions, rather than abstract cognitive functions.

References

- 'Reductionism and Antireductionism in Functionalist Theories of Mind' (1986), in The Philosophy of Mind: Classical Problems/Contemporary Issues (1992/1997), edited by Brian Beakley and Peter Ludlow.
- 'Neural Representation and Neural Computation' (1989)
Edelman, Gerald, quoted in John Horgan's The End Of Science (1996)
Kim, Jaegwon, 'Multiple realization and the metaphysics of reduction' (1992)
- 'Mental Causation' (chapter 6) in his Philosophy of Mind (1996)
Searle, John, 'Consciousness' (1999)
Wilson, E.O., quoted in What Philosophers Think (2003), edited by Julian Baggini and Jeremy Stangroom.
- Consilience: The Unity of Knowledge (1998)


3 comments:

  1. Paul, I wonder if you might be interested in starting up a discussion group on Facebook? If you do could you let me know because I don't want to lose touch with you. I'm following your blog but I'm much more regularly on Facebook.

    Best

    Jim

    ReplyDelete
    Replies
    1. Jim, it would be easier if you gave me with your email. I know that you have a programme on your own blog in which you click a link and you're taken straight to your email. However, it doesn't work for my computer. I tried to rectify it and in the process buggered-up my computer.

      Delete
  2. j.hamlyn at rgu.ac.uk

    BTW James Ragsdale has just started a group on Facebook that you might want to join called "Ethics and Moral Philosophy." It's not my area of interest really but it would be great to see you there.

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