Physical symbol system

A physical symbol system (also called a formal system) takes physical patterns (symbols), combining them into structures (expressions) and manipulating them (using processes) to produce new expressions.

The physical symbol system hypothesis (PSSH) is a position in the philosophy of artificial intelligence formulated by Allen Newell and Herbert A. Simon. They wrote:

"A physical symbol system has the necessary and sufficient means for general intelligent action."^[1]

This claim implies both that human thinking is a kind of symbol manipulation (because a symbol system is necessary for intelligence) and that machines can be intelligent (because a symbol system is sufficient for intelligence).^[2]

The idea has philosophical roots in Thomas Hobbes (who claimed reasoning was "nothing more than reckoning"), Gottfried Wilhelm Leibniz (who attempted to create a logical calculus of all human ideas), David Hume (who thought perception could be reduced to "atomic impressions") and even Immanuel Kant (who analyzed all experience as controlled by formal rules).^[3] The latest version is called the computational theory of mind, associated with philosophers Hilary Putnam and Jerry Fodor.^[4]

^ Newell & Simon 1976, p. 116 and Russell & Norvig 2003, p. 18
^ Nilsson 2007, p. 1.
^ Dreyfus 1979, p. 156, Haugeland 1985, pp. 15–44
^ Horst 2005

[NS-1] Newell & Simon 1976, p. 116 and Russell & Norvig 2003, p. 18

[FOOTNOTENilsson20071-2] Nilsson 2007, p. 1.

[:0-3] Dreyfus 1979, p. 156, Haugeland 1985, pp. 15–44

[4] Horst 2005

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