Thursday, December 4, 2008

Externalist Non-Reductive Materialism vs. Internalist Non-Reductive Materialism

Non-reductive materialism is the view that mental states are multiply realizable. As humans, dolphins, Martians and androids might all come under the intentional predicate of "believing that the fish are in the bucket," say, it follows that type-to-type identity fails: the type of intentional state we call "believing that the fish are in the bucket" cannot be identified with any specific type of neural state (some human neural state for example). The "materialism" part of non-reductive materialism is token-to-token identity: every token intentional state is identical, on this view, to some token physical state. This is a basic premise of functionalism: functional descriptions must replace physical descriptions because functions are multiply realizable (or, functions supervene on physical systems).
We can think about the difference between externalist non-reductive materialism and internalist non-reductive materialism. The internalist thinks that intentional predicates pick out states that are in the head (or body anyway, if you wish to be more careful). To say that "He believes that the fish are in the bucket" is to say that there is a particular state of affairs in his head, presumably some neural one. On the internalist view, what is multiply realizable is this internal process that in humans is essentially neural. We can see that this view is closely tied to representational models of nervous system function: if believing that the fish are in the bucket is a state of affairs (or a process) that is happening entirely in the subject's head this may entail that "fish," "the bucket" and so forth are somehow (images? formal symbols?) represented in the head.
But there is also the option of externalist non-reductive materialism. On this view intentional predicates apply to whole, embodied persons interacting with their environment. This looks to me to be right. Brains don't think any more than stomachs eat lunch: stomachs digest, persons eat lunch. Persons think, brains do...what? Seeing this question feels like progress. The externalist view is that mental predicates do not refer to brain states. That insight is interesting on the mental side, but it also washes back onto the question of what it is that neural processes in fact accomplish.


  1. As a Kantian, I take the view of transcendental idealism (math) in accordance with material realism (physics).

    (Empty) space, time, and numbers falsify the actual physcial world of objects, motion, and change, but we're only human.

  2. This is one of the most interesting and informative blog posts on the blogosphere.

    Thank you so much, Dr. Brown. Please, keep it up, for we keen and eager physicalists and naturalists out there!!

  3. How can a "token-to-token identity" be accomplished without either abandoning the "non-reductive" part of the view (by finding a physical means to achieve it), or abandoning "materialism" (by accepting a dualism)?

  4. Matt, Yes, the question is is anyone entitled to "nonreductive materialism" or must we choose between dualism and reductive materialism? In classical philosophy these positions are represented by Aristotle, Plato and Democritus respectively. Aristotle is understood as a nonreductive materialist variety of functionalist because he thinks that primary being is physical particulars, "substances," by which he means unions of form and matter. Thus he rejects the Platonic dualism of formal properties that exist whether or not they happen to be instantiated by physical particulars.
    My current view is that Plato might be right, that the existence of formal properties must be recognized as justifying metaphysical dualism. However viz-a-viz the mind/body problem I would then point out that the form/matter distinction is a general metaphysical problem, and that there is no metaphysical issue here, at least in so far as formal properties go, that is specific to the mind/body distinction.

  5. I'm only just getting to grips with a few contemporary philosophers, but it looks like it's time to do some more reading starting with the classics!

    Thanks for the reply, for the original post, and for the blog in general, all of which are Good Stuff!