Wednesday, July 9, 2008

Implicit Biological Naturalism

My view on the mind-body problem--a species of John Searle's Biological Naturalism--goes something like this. Brains cause minds--that is, if you knew everything about the physical structure of my brain, you could see how I couldn't but be in the mental state that I'm in--but minds are not eliminatively reducible to brain states. When I say "I believe George Bush is President," I'm saying something literally true, and I'm not just making a disguised (or confused) reference to my neuronal states. Similarly, when I (truly) say "I am in pain," I'm making a statement about a phenomenal sensation that is most certainly not true of my neurons yet most certainly is true of the system as a whole; the behavior of my neurons is the causal force directly behind my experience of pain, but that experience is not itself reducible to the neurons themselves. Consciousness, in short, is an emergent property of physical objects; it is something that the brain does in just the same way that digestion is something that the stomach does, and while we can say that my neuronal structure is causally sufficient for consciousness, it is not itself conscious.

That's a fairly brief characterization, and I'm working on cleaning it up a bit; there are problems with Searle's original formulation--mostly due to confused terminology and an unwillingness to accept certain things (like emergentism)--but I think he's basically got the right idea. Still, this isn't a position that's widely accepted in the philosophical community--most people still cling to one form of Functionalism or another.

There is, however, mounting evidence that Biological Naturalism (or something very like it) is starting to catch on in the scientific community. Today's issue of Nature contains a fascinating article about the difficulty of linking specific genotypes--that is, specific genes or specific kinds of damage to specific genes--to individual mental orders (e.g. schizophrenia or autism). The authors suggest that this might be because many psychiatric disorders might be cluster phenomena--in other words, constellations of related disorders that have radically different causes but share similar effects. A gene that sometimes seems to increase the risk factor for schizophrenia might be subtly altering some aspect of brain structure, and this alteration might in turn predispose one toward a certain behavior that might, in combination with another genetic accident, lead to psychosis; the system, in short, must be considered holistically in order to say anything meaningful about higher level features (such as thought disorders).

Vaughn over at Mind Hacks puts the issue even more explicitly in biological naturalist terms:

Genetics is a complex business, but psychiatric genetics even more so, because it attempts to find links between two completely different levels of description.

Genes are defined on the neurobiological level, while psychiatric diagnoses are defined on the phenomenological level - in other words, verbal descriptions of behaviour, or verbal descriptions of what it is like to have certain mental states.

There is no guarantee, and in many people's opinion, probably no likelihood, that these 'what it is like' descriptions actually clearly demarcate distinct processes at the biological level.

I couldn't have said it better myself. Mental illness, like conscious states in general, seems to me to me to be an emergent phenomenon: it can't be reduced to any one gene, neuronal process, or even type of brain activity, because the same phenomenal state can, given variations in the environment (in my broad sense, 'environment' includes neurobiological facts about the subject), be produced by very different physical phenomena. That's precisely why I think intentional (in the technical sense) language can't be eliminated from our "mental" vocabulary--statements about beliefs, desires, hopes, thoughts, and ideas are not reducible to statements about neurobiology, neither in a token/token sense nor in a type/type sense.



Derek James said...

Can you please clearly distinguish between Biological Naturalism and Functionalism? I don't get the difference. I thought a Functionalist basically said that the mind was what the brain did, like digestion is what a stomach does. So how are the schools of thought different?

Jon said...

I certainly can do that. Explanation forthcoming this evening!