Symbol Systems

A symbol is a pattern (of physical marks, electromagnetic energy, etc.) which denotes, designates, or otherwise has meaning. The notion that intelligence requires the use and manipulation of symbols, and that humans are therefore symbol systems, has been extremely in uential in arti cial intelligence. keywords: symbol, reasoning, intelligence, representation, logic This article has two parts. We begin with a presentation and discussion of the idea of a physical symbol system (PSS), as formulated by Newell and Simon. This notion, and the associated physical symbol system hypothesis (PSSH), were rst presented|under somewhat di erent names|in (Newell and Simon 1972), with later fuller formulations (Newell and Simon 1976, Newell 1980) and still later elaborations (Newell 1990). The second part consists of a discussion of various objections to PSS/PSSH and replies, especially with reference to the themes of symbol grounding, situated cognition, embodiment, and situated robotics.