Functionalism: Basics and Benefits

Today’s lecture was all about functionalism.  Sven tried to explain what functionalism is and what the benefits of functionalism are by comparing it and contrasting it with two other theories: philosophical behaviorism and type-type identity theory.

First, let‘s think about functional terms. “Key” is a functional term because it is defined by the function that it serves.  The definition does not give the kind of matter, shape or size of the object.  Rather, the definition is given entirely in terms of the function that it has.

“Flask” is also a functional term because it is defined by the function that it serves: to hold liquid.  A flask can be made of plastic, stainless steel or deerskin.  These details are not part of the definition.  Flasks are defined merely in terms of the function that they have.  This makes “flask” a functional term.

In order to understand functionalism by comparing and contrasting it to philosophical behaviorism and type-type identity theory, let’s remember what these theories are and note what some problems or limitations of these theories are.


Logical, or Philosophical Behaviorism is the view that Sam has mental state, M, if and only if Sam would behave in certain ways when faced with the appropriate circumstances. One problem with behaviorism is that one cannot explain behavior by talking about emotions or other mental states.  This is because  behaviorists think that emotions just are behaviors.  They cannot use emotions to explain behaviors!  This is the problem of mental causation.

Type-Type Identity Theory is the view that Sam has a mental state, M, if and only if Sam is in a particular brain state.  This view rules out the possibility that organisms with different brains are able to have the same brain states as us.  In other words, identity theorists must deny that there is the possibility of multiple realizability.  For example, a monkey cannot be sad because a monkey has a very different brain.  Or a dog cannot be in pain like humans because dogs have different brains than humans.  This consequence makes some people reject Identity theory.  This is called the problem of multiple realizability.

Functionalism is the view that there is a tight connection between behavior and mental states.  Sam has a mental state, M, if Sam has some kind of internal condition (such as a mental state or an experience that causes Sam to exhibit certain behaviors in the right circumstances.  In other words, mental states are functional states.  Pain is the kind of mental state that serves a function.  When Sam gets punched in the face, for example, pain may serve the function of making him cry out, run away and put ice on his face.

In other words, pain is a functional term of functionalists.  Pain is defined by the function or purpose that it serves.

Functionalism is like a blend of identity theory and of behaviorism, because functionalism is the view that mental states are closely connected with behaviors; it defines mental states via the behaviors but the mental states are not identified as behaviors  There is a major difference: behaviorism and identity theory are both forms of physicalism.  Functionalism is not a form of physicalism.  Functionalism leaves it open what kind of internal state is causing behaviors.  Therefore, functionalism is not vulnerable to the possibility that physicalism could be disproven.  Philosophers have been concerned that if physicalism were disproven, then behaviorism and identity theory would also be disproven.

Another benefit to functionalism is that it allows for the possibility of multiple realizability of emotions.  In other words, the possibility that different kinds of organisms (like humans, puppies and crows) are capable of having the same mental states such as pain, fear, thirst or calm. Putnam notes that an identity theorist cannot say that an animal or alien is in pain unless we have identified the physical-chemical brain state that is associated with brains.

One more benefit to functionalism is that functionalism can explain mental causation.  Because a functionalist does not identify mental states as behaviors, they can explain behaviors in terms of mental states and emotions, which is an option not open to the behaviorists.