A: Hanover, New Hampshire, United States, B: Santa Monica, California, United States

1955 to 7/1956

During 1955 and 1956 computer scientist and cognitive psychologist Allen Newell, political scientist, economist and sociologist Herbert A. Simon, and systems programmer John Clifford Shaw, all working at the Rand Corporation in Santa Monica, California, developed the Logic Theorist, the first program deliberately engineered to mimic the problem solving skills of a human being. They decided to write a program that could prove theorems in the propositional calculus like those in *Principia Mathematica* by Alfred North Whitehead and Bertrand Russell. As Simon later wrote,

"LT was based on the system of *Principia mathematica,* largely because a copy of that work happened to sit in my bookshelf. There was no intention of making a contribution to symbolic logic, and the system of *Principia* was sufficiently outmoded by that time as to be inappropriate for that purpose. For us, the important consideration was not the precise task, but its suitability for demonstrating that a computer could discover problem solutions in a complex nonnumerical domain by heuristic search that used humanoid heuristics" (Simon,"Allen Newell: 1927-1992," *Annals of the History of Computing* **20** [1998] 68).

The collaborators wrote the first version of the program by hand on 3 x 5 inch cards. As Simon recalled:

"In January 1956, we assembled my wife and three children together with some graduate students. To each member of the group, we gave one of the cards, so that each one became, in effect, a component of the computer program ... Here was nature imitating art imitating nature" (quoted in the Wikipedia article Logic Theorist, accessed 01-02-2013).

The team showed that the program could prove theorems as well as a talented mathematician. Eventually Shaw was able to run the program on the computer at RAND's Santa Monica facility. It proved 38 of the first 52 theorems in *Principia Mathematica*. For Theorem 2.85 the *Logic Theorist* surpassed its inventors’ expectations by finding a new and better proof. This was the “the first foray by artificial intelligence research into high-order intellectual processes” (Feigenbaum and Feldman, *Computers and Thought* [1963]).

Newell and Simon first described the Logic Theorist in Rand Corporation report P-868 issued on June 15, 1956, entitled *The Logic Theory Machine. A Complex Information Processing System*. (For some reason the only online version of this report available in January 2014 began on p. 25; however, the text available included the complete program.) The report was first officially published in September, 1956 under the same title in *IRE Transactions on Information Theory IT-2, *61-79.

Newell and Simon demonstrated the program at the Dartmouth Summer Session on Artificial Intelligence held during the summer of 1956.

Hook & Norman, *Origins of Cyberspace* (2002) no. 815.