Physical Symbol System

The basic properties laid out in these mathematical theories of computation define what is now known as a physical symbol system (Newell, 1980; Newell & Simon, 1976). The concept “physical symbol system” defines “a broad class of systems that is capable of having and manipulating symbols, yet is also realizable within our physical universe” (Newell, 1980, p. 136). A physical symbol system operates on a finite set of physical tokens called symbols.  These are components of a larger physical entity called a symbol structure or a symbolic expression.  It also consists of a set of operators that can create, modify, duplicate, or destroy symbols; some sort of control is also required to select at any given time some operation to apply.  A physical symbol system produces, over time, an evolving or changing collection of expressions. These expressions represent content, so a physical symbol system defines how meanings can be manipulated using formal processes.

References:

1. Newell, A. (1980). Physical symbol systems. Cognitive Science, 4, 135-183.
2. Newell, A., & Simon, H. A. (1976). Computer science as empirical inquiry - Symbols and search. Communications of the ACM, 19(3), 113-126.

(Added September, 2010)