Searle's Explanation of Consciousness
In explaining consciousness, modern philosophers and scientists have tended to reject the dualist idea that the mind, comprising such things as our perceptions and emotions, is something distinct from the body (i.e. the brain). The reason for this is that science is largely based on the idea that everything is objectively ascertainable. If you want to know what a human brain looks like, you can go look at one, and in the same way, indeed perhaps at the same time, you ought to be able to see what that person's mind looks like. The problem is, those theories seem not to explain things like qualia and intentionality, properties which it is asserted the mind has but not the body. (See the mind/body problem and Searle's Chinese Room for more).
Biological Naturalism is the name John Searle gives to his solution to the problem. Searle thinks it is a mistake to simply deny or forget about intentionality, and other characteristics of the mind that pose a problem for monists. At the same time, he denies Cartesian dualism, the idea that the mind is a separate kind of substance to the body, as this contradicts our entire understanding of physics, and unlike Descartes, he does not bring god into it. Indeed, Searle denies any kind of dualism, the traditional alternative to monism, claiming the distinction is a mistake. He shies away from the idea that because the mind is not objectively viewable, then it does not comprise part of physics: he simply says that science need not only be about the objective.
The biological naturalist view is, however, suspiciously similar to property dualism. It states that consciousness is not reducable to the physical, but is a an emergent property of the brain. That is to say, it is a property that comes from the physical, but is in a sense more than the sum of its parts. An example Searle gives to explain this is the liquidity of water. We understand it is the behaviour of H2O molecules that cause the liquidity, yet the molecules are not themselves liquid. A similar example can be given relating to electricity and the behaviour of electrons. Although Searle never uses the word, this sounds similar to what those who discuss the concept of supervenience are talking about. A supervenient property is one that is dependant on, but not the same as, a subvenient property. So in a newspaper picture, a subvenient property would be the tiny dots of ink, but arising from those is not only a large number of small dots, but a picture. And just like the dots in themselves are not the picture, the physical state of the brain is not consciousness.
John R. Searle, The Mystery of Consciousness (Granta 1997)
G. Veset and P. Foulkes, Unwin Hyman Dictionary of Philosophy (HarperCollins 1990)
Aaron Davidson, http://spaz.ca/aaron/school/bionat.html