In “Sensations and Brain Processes” by J.J. Smart, Smart argues that sensations are brain processes. This thesis claims “that in so far as a sensation statement is a report of something, that something is a brain process” (Smart 145). The use of the word “is,” in this particular case, refers to strict identity. This does not mean that the two entities are simply continuous in time and space, this “is” also means it “is identical with” in the strict sense, which must be clearly distinguished from the other kind of “is” that labels things that are identical to each other only in that they are time slices of the same four-dimensional object.
In order to support his thesis, Smart presents multiple objections to his thesis and then goes on to reply to these objections in order to strengthen his thesis. For example, the fourth objection is, “The after-image is not in physical space. The brain process is. So the after-image is not a brain-process” (Smart 150). His answer to this objection is that the experience of having an after-image is a brain process because it is reported in the introspective report. Smart thinks of retorts such as this to dismiss any possible objection to this theory and he does this pretty successfully. I, personally, could not think of another question or objection to his theory that he had not already answered. In fact, I believe that Smart’s theory is correct for reasons that are more scientific than philosophical.
Scientifically, Smart is correct. Any sensation that one could experience is a brain process. From sight to touch to pain to hearing, all sensations must be processed by the brain in order to be perceived. And as Smart says, the brain process itself is not a “yellowy-orange” something, but it is the experience of having that “yellowy-orange” something, and “there is such a thing as the experience of having an image, and this experience is described indirectly in material object language, not in phenomenal language, for there is no such thing” (151).
For example, in terms of vision, when you perceive that you are seeing something, light rays are reflected off objects and enter the eye through the cornea, which is the transparent front part of the eye that does most of the focusing by bending the light that passes through the pupil. This leads the light to the retina, which is the layer of tissue at the back of the eye containing photoreceptors and neural circuitry. There are two main types of photoreceptors in the retina: rods and cones. Both rods and cones turn the light into electrical signals, which the optic nerve sends directly to the brain. The primary visual cortex in the occipital lobe of the brain then perceives these signals into images. I learned this process in my neuroscience class and it applies to Smart’s theory because it scientifically shows that sensations are brain processes.
My question for the class is, is there a way you think that science could undermine Smart’s theory? If not, is there another challenge you would like to make to his theory?