The identity theory of the mind (ITM) is an extension of the more basic identity thesis (IT) which states that every property is a physical property. ITM is therefore the claim that every mental property is identitical to some physical property.
The ITM was well received in the middle part of the 20th century due to ontological simplicity: there was no longer a need to develop a separate ontology of the mind. The ITM allowed for one to say that the property of being in pain and the property of one's C-fibers firing are identitical (not distinct) properties.
However, the ITM faced several critiques in the latter half of the century, most from which it still has not recovered. The most important critique was the theory of multiple realizability which states that there are multiple physical states that can realize a single mental states and thus the identity fails.
Because of various critiques, several new derivations of the identity theory have surfaced. One of the most widley accepted of these versions is hardly an identity theory in that it accomodates functionalism and the multiple realizability argument. It can be stated as follows:
Every mental property is identical with a physical property or is realized on every occasion by a physical property.
Web Resources On Identity Theory
Book Resources On Identity Theory
Sensations and Brain Processes by J.J.C. Smart by
Supervenience and Mind by Jaegwon Kim by
Editor(s): Micah Sparacio