Functionalism (philosophy)

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The functionalism is one of the classic positions of the philosophy of mind . Your central thesis is that mental states are functional states.

Functionalism and Functional States

The core theme of the philosophy of mind is the mind-body problem. It arises from the question of the nature of mental states. Can they be integrated into a materialistic worldview or can they only be explained by an immaterial spirit ? Functionalism advocates the thesis that mental states are functional states. Since functional states can be realized by material systems , functionalism is generally understood as a materialistic position. However, it should be remembered that functionalism initially takes an ontologically neutral position: There is nothing in principle against the fact that immaterial systems - if there are any - can be functionally characterized.

A functional state is defined by the fact that it reacts to a certain input with a certain output and changes to another functional state. One can discuss the concept of a functional state using simple examples. The example of a coke machine comes from the philosopher Ned Block : Given a machine that dispenses a coke can after inserting one euro. He accepts 1 euro and 50 cent pieces. In order to be functional, the machine must have various internal states. There has to be a state in which the machine demands one euro to dispense a can, but there must also be a state in which the machine only demands 50 cents. The functional architecture of such a machine can be illustrated by the following simple table:

Current state Input output New condition
Z1 1 cola Z1
Z1 0.50 / Z2
Z2 1 Cola, 0.50 Z1
Z2 0.50 cola Z1

The machine has two different states, each of which reacts to two different inputs and can either remain in the same state or change to the other state. The functional states are defined by this table . The decisive factor in such a functional characterization of a system is that it is independent of the specific physical implementation of the system: It is completely irrelevant whether the machine is made of plastic or steel.

The thesis of functionalism is that mental states can also be defined in such a way. Anyone who is in a mental state (e.g. has a headache or thinks that today is Monday) will react to a certain input in a certain way and transition into another mental (functional) state. It is clear to all functionalists that the description of the mental inner workings must be much more complex than the description of a soda machine. The decisive factor in this thesis is that with it, the control over mental states is independent of the physical realization. So one could computer or robot mental states have when he realized only the same functional states like a living being with consciousness .

The evolution of functionalism

The development of functionalism is closely related to the problems of identity theory and the emergence of cognitive science . The identity theory was formulated by John Smart and Ullin Place in the 1950s . It says that a mental state - such as a headache - is identical to a certain neuronal state .

However, the objection to this theory was that it was empirically plausible that different beings can be in the same mental state even if they are in different neuronal states. For example, it can be assumed that humans and cats can have headaches. However, the brains are so different that it is implausible that they are in the same neuronal state. One speaks here in philosophy of multiple realization . So one cannot generally identify a headache with a particular neural condition.

One-band Turing machine

In addition, Artificial Intelligence (AI) and cognitive science emerged in the 1950s and 1960s . Identity theory, however, seemed to rule out a priori that a robot could ever have consciousness because it has no neural states.

In this situation, the functionalism first formulated by Hilary Putnam in 1960 appeared to be a clear improvement, since it describes functional states as independent of their concrete realization. So this functionalism has no problem with multiple realization. Nor does he rule out the possibility that systems without biological brains can have mental states. Even a Turing machine can theoretically realize any functional state. These advantages led functionalism to become the common philosophy of artificial intelligence and cognitive science. Due to the problems of functionalism, this status is now being called into question again.

Objections to functionalism

Despite its popularity, functionalism faces weighty objections.

Strange realizations

One of the classic objections to functionalism comes from the philosopher Ned Block . Block makes use of the fact that functional states can be implemented in different systems. Using a thought experiment, Block tries to imagine a situation in which a system has the same functional architecture as a conscious person, but still no consciousness. If such a system could exist, then functional states cannot be identical to mental states.

In the Troubles with Functionalism article, Block envisions that the Chinese government is conducting a large-scale functionalism experiment. Each of the 1.3 billion Chinese gets a radio with which they can contact other Chinese. The whole thing is coordinated by huge headlights that project commands onto the cloud cover. Such a system consisting of people, radios and headlights could, according to Block, realize any functional state that a person can realize, at least for a short time. Still, according to Block, it would be completely absurd to assume that such a system would have mental states. Therefore, functional states and mental states cannot be identical. Block's objection has come to be known as the "Strange Realizations" objection.

Qualia

John Searle - one of the most influential critics of functionalism (Berkeley 2002)

Functionalism also has to contend with a problem that even many proponents - such as Jerry Fodor - consider unsolved. If all mental states are functional states, then experiences such as pain must also be functional states. It is undoubtedly plausible that pain can also be described functionally: Those who are in pain will usually tend to behave in a certain way - e.g. B. lying in bed but not dancing - and also having certain other mental states - such as sadness, but not euphoria.

The decisive question, however, is whether the functional description already fully covers the phenomenon of pain. And this raises serious doubts: Sure, functional characterization is an important part of pain, but another element seems much more important: experiencing pain . However, the fact that we experience pain - that is, have pain qualia - does not seem to be taken into account in any way by the functional description. The accusation against functionalism is therefore that it cannot explain the qualia or experience content of mental states. It is therefore unclear whether a certain functional architecture is sufficient for experience. It therefore seems implausible to equate mental states with functional states. To illustrate this, think of a computer that has the same functional structure as a person in severe pain. Does the computer actually experience pain?

Daniel Dennett now claims to have solved the qualia problem .

Externalism

Hilary Putnam , who himself was one of the founders of functionalism, is now considered one of the most influential critics of this position. His best-known arguments against functionalism are related to the externalist slogan: " Thoughts are not in the head". Putnam tries to show that a thought is not an internal state, but is co-constituted by the community and the environment. But since functional states are internal states, an identification of mental and functional states is not possible. Putnam offers two arguments:

1) Elms and beeches: Putnam explains that all he knows about elms and beeches is that they are trees. This means that the internal functional structure of these thoughts can be the same. However, the thoughts “the elm is a tree” and “the beech is a tree” are different because they refer to different things. But if thoughts can be different even though the functional structure is the same, then thoughts and functional states cannot be identical.

2) Twin Earth : Putnam's second argument is based on a thought experiment : He imagines a planet that resembles our world in every detail. There is only one difference: what is H 2 0 for us is a substance XYZ on twin earth, but it has the same macro properties as water. So it is liquid, transparent, odorless etc. Now a person A on earth has the same functional structure as his twin B on twin earth. However, they have a few different thoughts: A with the thought “water is liquid” refers to the substance H 2 O , B with the same thought refers to XYZ. The result: Since people with the same functional organization can have different thoughts, thoughts are not identical to functional states.

Variants of functionalism

Within functionalism, a distinction is made between two different currents, depending on whether the mental states are determined by everyday psychology or scientific psychology . According to the first alternative, our everyday terms such as “pain”, “joy” or “anger” are functionally determined. This position is also called common sense functionalism . According to the second position, it is rather a question of states that have been determined in psychological research. Accordingly, one speaks of "psychofunctionalism".

David Lewis' theory is compatible with the thesis that mental states are identical to brain states.

David Lewis combined common sense functionalism with elements of identity theory: while everyday psychological terms are only functionally characterized, the mental states of an individual are in turn identical with their neural states and can be reduced to them.

See also

  • For functionalism in the context of other positions , see: Philosophy of Mind
  • For the connection between empirical research and functionalism, see: Cognitive Science .
  • For the formal background to the definition of functional states, see: Automat

literature

Introductory texts

Basic texts of functionalism

  • Hilary Putnam : Minds and Machines , Hook: Dimensions of Mind, New York, Collier Books, 1960
  • Jerry Fodor Psychological Explanation , New York, Random House, 1968
  • David Lewis : Mad Pain and Martian Pain , in: David Lewis: Philosophical Papers Vol.1, Oxford, Oxford University Press, 1983
  • Daniel Dennett , Consciousness Explained , 1991, Boston: Little, Brown (German philosophy of human consciousness ; translated by Franz M. Wuketits )
  • Daniel Dennett , Sweet Dreams. Philosophical Obstacles To A Science Of Consciousness , MIT Press, Bradford Book, 2005 ( sweet dreams, 2007 )

Critique of Functionalism

Web links

This version was added to the list of articles worth reading on November 17, 2005 .