Functionalism is a philosophical thesis about the nature of mental states. According to functionalists, mental states are identified by what they do rather than by what they are made of. The core idea of functionalism is that what makes something a mental state is more a matter of what it does, not what it is made of. Functionalism is the view that each and every mental state is constituted solely by its functional role, which means its causal relation to other mental states, sensory inputs, and behavioral outputs). It is a theoretical level between the physical implementation and behavioral output). Functionalism is different from its predecessors of Cartesian dualism (advocating independent mental and physical substances) and Skinnerian behaviorism and physicalism (declaring only physical substances) because it is only concerned with the effective functions of the brain, through its organization or its "software programs").
Functionalism is fundamentally what Ned Block has called a broadly functionalist family of views). There are different types of functionalist theories, and they take the identity of a mental state to be determined by its causal relations to sensory stimulations, other mental states, and behavior. Functionalism is the most familiar or “received” view among philosophers of mind and cognitive science.
