Identity Thesis

Over the course of history, different theories have been formulated to help explain the complex relationship between the mind and the body. One of the theories elucidating the mind-body relation is dualism—the view that mental states are independent from physical states. Mental states are ones of thinking, feeling, and believing whereas physical states are those outlined by physical and biological sciences. In contrast to dualism, physicalism insists that mental states are somehow physical states. The most straightforward version of physicalism is the identity thesis—the theory that every type of mental state is identical to some type of physical state (Reasons and Responsibility, 285-286). Dualists and physicalists have disputed over the validity of the identity thesis; dualists denying its claim and physicalists defending it. The biggest problem facing physicalists and the identity thesis is the concept of qualia, the phenomenal quality of a mental state (Reasons and Responsibility, 281). Philosopher Frank Jackson offers what he calls the “Knowledge Argument” for qualia. Jackson’s knowledge argument presents that nonphysical facts can be devised from facts about phenomenal quality. Through the concept of qualia, Jackson’s knowledge argument shows that the identity thesis is false.
The identity thesis holds that mental events are simply identical with brain processes—identical in the same manner that sounds are identical with density waves in the air. The thesis bases on the idea that mental states of thought, sensation, and awareness are alike those of physical states (such as those of the brain and central nervous system). An example of identity thesis is that lightning and an electric charge are two of the same thing. In other words, lightning is an electric charge. An advocate of the identity thesis is materialist Peter Carruthers. Carruthers argues that everything (including mental states) exists through physical causes. Carruthers’ argument for the