Why Brains?

Big Brain

Originally uploaded by Pete Mandik.

It seems to be an open question whether distinctively neural properties are essential to the instantiation of mental properties. One can buy into reductive physicalism and reject neural reduction bases in favor of chemical or thermodynamic reduction bases, just to name a few. Perhaps, then, systems that have no distinctively neural properties—no brains and no neurons—nonetheless have certain chemical or thermodynamic profiles that suffice for mentality. Perhaps. But I doubt it. I hope that I may be forgiven for being so brief about this, but I think there are three reasons (at least) for thinking that the physical reduction of the mental should be a neural reduction.

The first reason for believing in neural reduction is that no non-controversial examples of entities that implement consciousness or cognition exist without brains, or at least, neural networks. It is uncontroversial that alert human adults have mental states. It is also uncontroversial that they have brains. Things are much more contested for the brainless. While it is arguable that my laptop has mental properties, it is also arguable that it does not. It is also arguable, by the way, whether or not my laptop has neural properties. I do, after all, run neural network simulations on it (Mandik 2003). How many properties are literally shared by the simulation and the simulated? We need not settle this now. What is clear is that there’s controversy about the mental prowess of the brainless. And while some brain-havers may lack mentality (who knows what to say about the vegetative patients? (Begely 2006) ), there are no uncontroversial confirmations of mind-havers lacking brains. Let’s talk about the mind-having brain-havers a bit more under the heading of “reason #2 for thinking that the physical reduction bases of mentality will be neural.�

The second reason for believing in neural reduction is that there is no reason to doubt that that it is in virtue of their brains (or their brains plus something else) that creatures like us implement consciousness or cognition. Putting the parenthetical “plus something else� to the side for the moment, let us entertain briefly how unpromising non-neurocentric theories have been. Mental properties are had by organisms either in virtue of the whole organism or part and it is easy to see that it can’t be the whole organism. Amputees retain their mentality, and while my appendectomy doesn’t exactly count as an amputation, comparing its relative effect to one’s mentality to the potential effects of a lobotomy is like comparing nothing to something. That the seat of our soul is some proper part of us is old news, but the appendix never had a chance and the Aristotelian coronary hypothesis was rejected long ago. So much of what we know about where drugs need to go to go to work and what brain injuries impair what mental functions has tipped the scales pretty clearly in favor of neruo-centrism. But, must it be merely neuro-centric? Can’t it be exhaustively neural? Here we have to pause to consider various embodied, embedded, and externalist proposals for including the body and even chunks of the environment of the organism as part of the supervenience base of the organism’s mental properties. There are a couple of things to say about this. The first is that none of it removes the brain from the center of the story. The second is to echo Fodor’s (1989) suggestion that we individuate neural properties widely.

The third reason for believing in neural reduction is that no reductive research program has been as productive as neurocentric ones. One might even be so bold as to suggest that non-neurocentric reductionists have no research program at all. There have been, in recent decades, three major proposals that have been physicalistic without reducing mentality, a la behaviorism, to the behavior of whole organisms: classic computationalism, connectionism, and (certain versions of) dynamic systems theory. Classicism got wedded, in many people’s minds, to non-reductive physicalism, largely due to the influence of Fodor (1974) and Putnam (1967). Dynamic systems theory included proposals of a specifically neural character, (e.g. Freeman 1991) while others looked like warmed-over behaviorism (van Gelder, 1995). Either way, dynamic systems theory was confronted with some devastating objections (see Glymour (1997), Grush, (1997) and Eliasmith (2001) for a taste). The main point here, though, is not any knock-down refutations of non-neurocentric research programs. The point here is that neurocentric research programs have been massively productive both in theory and in application.

[From "Supervenience and Neuroscience"]

Update: Futher discussion of this post on Paul Baxter’s blog [link].

4 Responses to “Why Brains?”

  1. I still need to parse this article a little further, but I think I’m in general agreement. There’s a scale/level of analysis thing that still bugs me when becoming neurocentric… so I have to think.

    Also- in case you don’t regularly read comments on your old flickr photos, I have laid out a challenge for TMS - Bowling on your ‘take the neuroscientists bowling’ photo.

  2. Pete Mandik says:

    I accept the TMS Bowling challenge. Also, it’s too brilliant to be buried in a flickr comments thread.

  3. Ignacio Prado says:

    Hi Pete,

    This is an interesting way of arguing for reductionism, though it seems like a largely empirical and inductive argument for a metaphysical conclusion, which is tough to pull off in any context.

    The inductive-empirical argument is (to oversimplify)

    1. Everything that we’ve encountered with mental properties of a certain type has had a neural organization of a certain type (inductive factor 1).
    2. Assuming that mental properties are essentially dependent on a neural orgnaization of a certain type has been the most empirically fruitful assumption for the scientific study of cognition and experience (inductive factor 2).
    Given inductive factors 1 and 2, the most reasonable belief is that mental properties of a certain type are essentially dependent on and/or constituted by and/or realized in a neural organization of a certain type.

    The problem with (1) is that it is hard to establish without loading the inductive dice against a lot of alternative hypotheses. Everything we’ve encountered with a mind has either descended from mitochondrial Eve or been designed by something that has descended from mitochondrial Eve. Does that mean we should accept some kind of origins essentialism for having mental properties of a certain type, if we want to use these inductive arguments? Likewise, everything we’ve encountered with a mind has been from Earth. Should we be essentialists about earthly origins and discount the possibility of Martian minds that have the right neural organization? How do you sideline these noisy facts (in a principled way) as irrelevant to having mental properties of a certain type when making an inductive argument for neural reductionism?

    The challenge to (2) would be less philosophical. A lot of what goes on in linguistics is, for better or worse, independent of worries about neural realization. Is that a reason to be suspicious of linguistics as curently practiced as a discipline for telling us something important about the mind, or is it a reason to be suspicious of neural reductionism?

  4. Pete Mandik says:

    Hi Ignacio,

    Thank you for your thoughtful comment. Please forgive the delayed reply. I got married on Jan 20 and have only recently returned from my honeymoon in Prague.

    Before responding to your main points, I wanted to briefly comment on your remark regarding drawing metaphysical conclusions from inductive and empirical premises. Your remark seems to suggest that it is easier to draw metaphysical conclusions from non-inductive and non-empirical premises. If “conclusions” is supposed to suggest something like “established results” then I would say that there are no premises from which metaphysical conclusions follow easily, if at all. Metaphysics has had a pretty poor track record in the established results business.

    On to your main points.:

    You summarize my argument as having two main pieces, but I intended it to have three. Sticking with your numbering scheme, let’s call the one you left out the explanatory factor or factor 3:

    (3) there is no serious doubt that minded creatures with brains have their minds in virtue of their brains.

    I think the challenge you raise for (1) is correct, but this sort of challenge can be raised for any straight induction, which is why straight inductions by themselves don’t do very much work in science. However, this is not to say that such inductions are entirely useless. When coupled with an explanatory story, as in the kinds of explanations alluded to in (3), inductive considerations like those in (1) carry more weight. So, for example, while it is both true that all minded creatures have brains and all minded creatures are sons and daughters of Mitochondrial Eve, the descent from Eve does no explanatory work regarding cognition whereas the nervous system does.

    Regarding the challenge you raise for (2) regarding contemporary linguistics, I’m skeptical that it pulls much weight. All current linguistic theory is based on the linguistic behavior of creatures with brains (point (1) again) and there’s no serious doubt that linguistic competence is accomplished in virtue of brains (point (3) again). These points stand regardless of whether contemporary linguistic theory makes explicit mention of brains and things brainy as such. In other words, the ontology of linguistic theory may have a neural reduction base regardless of whether current theory employs an explicitly neural vocabulary. Regarding your final question of whether this is a problem for either reductionism or linguistics, I’d say it’s a problem for linguistics insofar as something remains unexplained.