In 1956, three researchers from the RAND Corporation and the Carnegie Institute of Technology unveiled a remarkable invention: a computer program that could prove mathematical theorems and suggest new ones. The program, called the Logic Theorist (LT), was the first of its kind to demonstrate the possibility of artificial intelligence, or the ability of machines to perform tasks that normally require human intelligence.
The Logic Theorist was the brainchild of Allen Newell, Herbert Simon, and Cliff Shaw, who shared a common interest in the nature of human problem solving and decision making. They wanted to create a program that could mimic the reasoning skills of human mathematicians, especially those used in the field of logic. They chose to test their program on the theorems from Principia Mathematica, a monumental work by Alfred North Whitehead and Bertrand Russell that attempted to establish the foundations of mathematics using symbolic logic.
The Logic Theorist used a programming language called Information Processing Language (IPL), which was designed by Shaw specifically for the project. IPL allowed the program to manipulate symbols and expressions, as well as store and retrieve information from memory. The program also used a technique called heuristic search, which enabled it to explore different paths of reasoning and select the most promising ones. The program could apply various rules of logic, such as modus ponens and substitution, to generate and test possible proofs.
The Logic Theorist was able to prove 38 of the first 52 theorems in the second chapter of Principia Mathematica, and found new and shorter proofs for some of them. The program also discovered a new theorem that was not in the original book, which it called Theorem 2.85a. The program’s proofs were so elegant and concise that Newell, Simon, and Shaw submitted one of them to the Journal of Symbolic Logic, where it was accepted for publication. The program’s achievement was hailed as a breakthrough in the field of artificial intelligence, which was just emerging at the time.
The Logic Theorist was not only a scientific innovation, but also a philosophical challenge. It raised questions about the nature and limits of human intelligence, and the possibility of creating machines that could surpass it. It also inspired further research and development in artificial intelligence, such as the General Problem Solver, another program by Newell and Simon that could solve a wide range of problems using heuristic methods. The Logic Theorist was the first step in a long and fascinating journey of exploring the potential and implications of artificial intelligence.