Biological naturalism
Biological naturalism is a theory about, among other things, the relationship between consciousness and body (i.e. brain), and hence an approach to the mind–body problem. It was first proposed by the philosopher John Searle in 1980 and is defined by two main theses: 1) all mental phenomena, ranging from pains, tickles, and itches to the most abstruse thoughts, are caused by lower-level neurobiological processes in the brain; and 2) mental phenomena are higher-level features of the brain.
This entails that the brain has the right causal powers to produce intentionality. However, Searle's biological naturalism does not entail that brains and only brains can cause consciousness. Searle is careful to point out that while it appears to be the case that certain brain functions are sufficient for producing conscious states, our current state of neurobiological knowledge prevents us from concluding that they are necessary for producing consciousness. In his own words:
Criticism[edit]
There have been several criticisms of Searle's idea of biological naturalism.
Jerry Fodor suggests that Searle gives us no account at all of exactly why he believes that a biochemistry like, or similar to, that of the human brain is indispensable for intentionality. Fodor thinks that it seems much more plausible to suppose that it is the way in which an organism (or any other system for that matter) is connected to its environment that is indispensable in the explanation of intentionality. It is easier to see "how the fact that my thought is causally connected to a tree might bear on its being a thought about a tree. But it's hard to imagine how the fact that (to put it crudely) my thought is made out of hydrocarbons could matter, except on the unlikely hypothesis that only hydrocarbons can be causally connected to trees in the way that brains are."[2]
John Haugeland takes on the central notion of some set of special "right causal powers" that Searle attributes to the biochemistry of the human brain. He asks us to imagine a concrete situation in which the "right" causal powers are those that our neurons have to reciprocally stimulate one another. In this case, silicon-based alien life forms can be intelligent just in case they have these "right" causal powers; i.e. they possess neurons with synaptics connections that have the power to reciprocally stimulate each other. Then we can take any speaker of the Chinese language and cover his neurons in some sort of wrapper which prevents them from being influenced by neurotransmitters and, hence, from having the right causal powers. At this point, "Searle's demon" (an English speaking nanobot, perhaps) sees what is happening and intervenes: he sees through the covering and determines which neurons would have been stimulated and which not and proceeds to stimulate the appropriate neurons and shut down the others himself. The experimental subject's behavior is unaffected. He continues to speak perfect Chinese as before the operation but now the causal powers of his neurotransmitters have been replaced by someone who does not understand the Chinese language. The point is generalizable: for any causal powers, it will always be possible to hypothetically replace them with some sort of Searlian demon which will carry out the operations mechanically. His conclusion is that Searle's is necessarily a dualistic view of the nature of causal powers, "not intrinsically connected with the actual powers of physical objects."[3]
Searle himself does not rule out the possibility for alternate arrangements of matter bringing forth consciousness other than biological brains. He also disputes that Biological naturalism is dualistic in nature in a brief essay entitled "Why I Am Not a Property Dualist".