Brain in a vat

The brain in a vat (English brain in a vat) is a thought experiment in which the objective is to rethink our ideas of knowledge, reality, truth, consciousness and meaning. Is used an example of a computer, which supplies an artificial brain with electric pulses, as would a real body. There then arises the question whether the brain can determine if it is in a real environment, ie a real body, or in a simulated reality.


In many science fiction stories, the idea occurs that a mad scientist a human operated out of the brain and stored in a tank in nutrient solution and its neurons connects by wires to a computer, which supplies it with exactly the same electrical pulses as a brain normally receives. In such stories, the computer simulates a virtual reality, including appropriate responses to the output of the brain, and the person with the disembodied brain is still completely normal experiences in their consciousness, without them having to do with objects or events in the real world.

The brain - in -tank scenario is used as an argument for skepticism and solipsism. A simple version of the argument is this: Since the brain in a vat exactly sends the same signal and receives, as if it were in a head, and since these are his only link to the outside world, it is from the perspective of the brain impossible to say whether it is located in a header or in a tank. In the first case, most of the ideas of the person may be true, for example, if the person thinks that she walks the street or eating ice cream. In the second case, but the ideas are wrong. Since you now but can not determine whether you are a brain in a vat, one can not know if not most things that one believes are completely wrong. Since one can not in principle exclude the possibility that one is a brain in a vat, there can be no good reason to believe anything of what you believe, and you can definitely know nothing about it.

This argument is today's version of the argument that Descartes in Meditations on First Philosophy for it ( but ultimately rejects ) that he could not believe his perceptions, because an evil spirit may be controlling all his experiences. Distant cousins ​​she is also to Descartes ' argument that he could not trust his perceptions because he may only dreaming - the concern is omitted, that he would actively misled.

Philosophical considerations

In recent decades, philosophers have dealt in various ways with questions of this kind. Some, such as Barry Stroud, say that here there would be a peremptory objection to any knowledge claim. Other wise this back, best known thereof Hilary Putnam. In the first chapter of his book Reason, Truth and History claims Putnam, the thought experiment is inconsistent in that a brain in a tank, the kind of story and interaction with the world would not have that would allow him on the tank in which it is to think or say anything. Putnam uses the thought experiment as an argument for his ( controversial ) internal realism. In addition, there must be at least one intelligence -controlled body that built the apparatus and the brain has connected to it.

The brain - in -tank design in popular culture

Many films rely on similar ideas, such as Vanilla Sky and matrix. The idea that the brain - or more abstract: his consciousness - is removed from the body, immersed in some of the novels of Stanisław Lem on, as is the related idea that an artificial consciousness by a mad scientist who has created it, with artificial stimuli is fed. In the novel " Ubik " by Philip K. Dick recently deceased live a telepathic simulation further, while their brains to rest in a nutrient solution. Benjamin Stein into his novel Replay ( 2012) model of a brain -computer interface through which also includes the manipulation of real experienced as memories, a subject that has already been created in the film Strange Days (1995).