Brain in the tank

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Reality imagined in the brain and actual reality do not match in this thought experiment .

The brain in the tank (English brain in a vat ) is an argument that is used in a variety of philosophical thought experiments . It is designed to question concepts such as knowledge , reality , truth , spirit , awareness and meaning .

A brain that is artificially kept alive in a tank is presented, which is stimulated by a computer with electrical impulses, just as the nerve lines of a real body would do, so that a (simulated) reality emerges from the perspective of the brain. The question then arises as to whether the brain can determine whether it is in a real environment, i.e. a real body, or in a simulated reality , and whether this is ethically and epistemologically relevant.

Hillary Putnam has presented a much debated attempt to refute the argument.

Skeptical argument

The brain-in-tank is used as an argument for skepticism and solipsism . The argument presupposes the principle of the unity of knowledge . This means: if I know a proposition p, then I also know what follows logically from p. In other words: If I don't know what follows logically from p, then I don't know p either. Let p be any proposition about the world, e.g. B. that water is H 2 O.

A simple form of the argument is:

(I) If I know that p, then I also know that I am not a brain in the tank.

(Ii) I can't know if I'm a brain in the tank.

(III) Therefore I do not know that p.

This argument is today's version of the considerations that Descartes makes in Meditationes de prima philosophia . After he has established that he alone cannot doubt that he exists as a subject of knowledge, he states that he cannot trust his perceptions because it is conceivable that an evil spirit may control all of his experiences.

Philosophical considerations

In the last few decades representatives of analytical philosophy in particular have dealt with questions of this kind in a variety of ways. The starting point was Gilbert Ryle's metaphor for the relationship between body and mind in Descartes' philosophy, which he described as "Ghost in the Machine". Based on this, several thought experiments were developed, such as the Chinese Room by John Searle and the Brain in the Tank by Hilary Putnam , to take a stand in the debate on the philosophy of mind between behaviorism , theories, traditional dualism and functionalism. Some, like Barry Stroud , say that there is an irrefutable objection to any claim to knowledge here.

Putnam's attempt at refutation

Hillary Putnam tried to refute the brain in the tank scenario. He argues for a semantic externalism . This states that there are a number of singular and general terms that depend on the speaker's external environment. Accordingly, the brain in the tank scenario cannot be true. If it were true, then the words "brain" and "tank" would not refer to anything. The phrase "I'm a brain in a tank." would necessarily be wrong.

The brain-in-a-tank motif in popular culture

Braininvat.jpg

Many science fiction stories have come up with the idea that a mad scientist will operate on a person's brain and store it in a tank in nutrient solution, and connect his neurons by wires to a computer that will provide it with exactly the same electrical impulses as a Brain receives them normally. In such stories, the computer simulates a virtual reality , including appropriate responses to the brain's output, and the person with the disembodied brain continues to have perfectly normal experiences in their consciousness, unrelated to objects or events in the real world.

Many films take up similar ideas, such as Vanilla Sky , Matrix and its sequels. The idea that the brain - or, more abstractly, its consciousness - is taken out of the body emerges in some of Stanisław Lem's novels , as well as the related idea that an artificial consciousness is created by a mad scientist who created it with artificial Stimulating is fed. In the novel, Ubik by Philip K. Dick deceased live in a recent telepathic simulation further, while their brains rest in a nutrient solution. In his novel Replay (2012) Benjamin Stein carried out the model of a brain-computer interface that also contained the manipulation of memories that were experienced as real , a motif that was already laid out in the film Strange Days (1995).

literature

  • Georg Kamp, Brain in the Tank , in: Jürgen Mittelstraß (Hrsg.), Encyclopedia Philosophy and Philosophy of Science , 2nd Edition, Vol. 3. Metzler, Stuttgart, Weimar 2008 (with detailed references)
  • Olaf L. Müller, Reality Without Illusion I: Hilary Putnam and Farewell to Skepticism or Why the World Cannot Be a Computer Simulation, Vol. 1, mentis, Paderborn: 2003.
  • Olaf L. Müller, Reality without Illusion II: Metaphysics and Semantic Stability or What It Means to Ask about Higher Realities, Vol. 2, mentis, Paderborn: 2003.

Web links

Commons : Brain in a vat  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f Michael McKinsey: Skepticism and Content Externalism . In: The Stanford Encyclopedia of Philosophy . Summer 2018 edition. Metaphysics Research Lab, Stanford University, 2018 ( stanford.edu [accessed August 9, 2020]).
  2. ↑ a b Putnam, Hilary .: Reason, truth, and history . Cambridge University Press, Cambridge [Cambridgeshire] 1981, ISBN 978-0-511-62539-8 , pp. 1-21 .
  3. ↑ Brain in a Vat Argument, The | Internet Encyclopedia of Philosophy. Retrieved August 9, 2020 (American English).