Use stream of consciousness to answer the following. In philosophy, the brain in a vat (alternately known as brain in a jar) is a scenario used in a variety of thought experiments intended to draw out certain features of human conceptions of knowledge, reality, truth, mind, consciousness and meaning. It is an updated version of Rene Descartes' Evil Demon thought experiment originated by Gilbert Harman. Common to many science fiction stories, it outlines a scenario in which a mad scientist, machine, or other entity might remove a person's brain from the body, suspend it in a vat of life-sustaining liquid, and connect its neurons by wires to a supercomputer which would provide it with electrical impulses identical to those the brain normally receives. According to such stories, the computer would then be simulating reality (including appropriate responses to the brain's own output) and the "disembodied" brain would continue to have perfectly normal conscious experiences, such as those of a person with an embodied brain, without these being related to objects or events in the real world.

Answer this question based on the passage: who came up with the brain in a vat theory?
This is the relevant information: It is an updated version of Rene Descartes' Evil Demon thought experiment originated by Gilbert Harman. Final answer: Gilbert Harman.