Identity Theory (Philosophy of Mind)

from Wikipedia, the free encyclopedia

The identity theory is one of the classic positions of the philosophy of mind . It is a naturalistic theory whose central thesis is that mental states are identical to neural states .

From behaviorism to identity theory

Representation of the identity theory: All mental states m1-m5 belong to the same mental type (such as “blue perception”). They are identical to neural states n1-n5, which in turn belong to the same neural type. The types are therefore also identical.

Identity theory was formulated by Ullin Place and John Smart in the 1950s . The two philosophers made two assumptions:

  1. Philosophical behaviorism , which attempted to completely replace mental terms with physicalistic terms (having the same meaning), is incomplete. Not all mental expressions can be defined in physicalistic language: for example, sensations (such as color perception or pain) cannot be fully analyzed as behavioral dispositions.
  2. The dualism of spiritual and physical is wrong - the incompleteness of philosophical behaviorism does not mean that materialism has failed .

Place and Smart, on the other hand, propose that consciousness or mental states such as sensations are identical to brain states . This identity is therefore not a question of the meaning of mental expressions, as was assumed in philosophical behaviorism , but simply an empirical discovery.

The systematic development of identity theory is an achievement of the 20th century. Even before Smart and Place it was discussed in the Viennese circle, it was conceived by Moritz Schlick and, in the course of the 1950s, continued and specified by Feigl in particular.

After philosophical behaviorism had proven to be practical and theoretically impracticable in the course of the 1950s and 1960s, identity theory, following Place and Smart, was extended beyond the narrower domain of consciousness and sensations to the domain of propositional attitudes . Today the identity theory is mostly connected with the thesis that all mental states are identical to brain states.

The identity theory can be explained with the help of simple examples - for example the identity of water and H 2 O. If we find that water is identical to H 2 O, then we have scientifically explained the phenomenon "water". Analogous to this: If we have established that a mental state is identical to a brain state, we have scientifically explained the phenomenon of "mental state". It should be noted that water has a different meaning than H 2 O. The meaning of H 2 O includes being a molecule . That does not belong to the meaning of water. Nevertheless, one could say that water is identical to H 2 O. Two entities can be identical without having the same meaning. Analogous to this: expressions for mental states and expressions for brain states have different meanings , but can still refer to the same phenomenon and thus denote identical things. This enables a materialistic position beyond philosophical behaviorism .

Identity theory briefly became the most important position in the analytical philosophy of mind ; it has significantly shaped this part of philosophy in its present form. As early as the late 1960s, however, this concept was rejected again by many philosophers.

Objections to Identity Theory

Identity theory faced many objections from the start. Two are mentioned here:

1. Identity theory was generally understood as a reductionist theory that seeks to reduce the mental to the physical. Identity , however, is a symmetrical relation . It was therefore argued that identity theory not only materializes the mental, but also "spiritualizes" the material: mental properties are ascribed to the states of the brain.

For clarification, the above mentioned. Example of the identity of water and H 2 O serve. For example, water has the properties of being liquid and transparent. But if water and H 2 O are in reality identical, they must have the same properties: Water is nothing else than H 2 O. So H 2 O is also liquid and transparent. Does this example also apply to the identity of mental state and brain state? Does it make sense to say of a neural condition that it is painful or stabbing?

2. The decisive objection, however, relates to the multiple realization : A mental state can be realized in different beings through very different brain states. So pain cannot be the same as a specific brain state.

Humans can be in pain, including cats and (probably) amphibians. Now it is unlikely that all beings are in the same neuronal state when they are in pain. The brains are too different. Let's call the neuronal states M (in humans), K (in cats) and L (in amphibians). If the different neuronal states M, K and L now all realize pain, then pain simply cannot be identical to one of these states.

From identity theory to functionalism - and back?

In particular, the objection of multiple realizations contributed to the rapid decline in popularity of identity theory. Hilary Putnam , who brought the objection into play in 1967, also offered an alternative: functionalism . The different brain states should all realize a functional state, which is then identical to the mental state. The construction plan of a clock can be used as an example: The construction plan specifies functional states. The clock can be built from various materials, all of which realize the functional states. Functionalism became the "orthodox doctrine" in the philosophy of mind for the following decades.

Recently, however, there have been increasing numbers of voices calling for a return to identity theory. It should be noted that functionalism could not solve the problem of qualia . In addition, considerations by Jaegwon Kim about multiple implementation play a major role here.

literature

See also

Web links