Cover: The Logic Theory Machine

The Logic Theory Machine

A Complex Information Processing System

Published 1956

by Allen Newell, Herbert Alexander Simon

Download eBook for Free

FormatFile SizeNotes
PDF file 3.5 MB

Use Adobe Acrobat Reader version 10 or higher for the best experience.

In this paper, RAND researchers describe a complex information-processing system — the logic theory machine — capable of discovering proofs for theorems in symbolic logic. In contrast to the systematic algorithms ordinarily employed in computation, this system relies heavily on heuristic methods similar to those that have been observed in human problem-solving activity. The specification is written in a formal language, of the nature of a pseudo-code, that is suitable for coding for digital computers. However, the authors are concerned with specification of the system rather than its realization in a computer. The logic theory machine is part of a program of research to understand complex information-processing systems by specifying and synthesizing a substantial variety of such systems for empirical study.

This report is part of the RAND paper series. The paper was a product of RAND from 1948 to 2003 that captured speeches, memorials, and derivative research, usually prepared on authors' own time and meant to be the scholarly or scientific contribution of individual authors to their professional fields. Papers were less formal than reports and did not require rigorous peer review.

This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited; linking directly to this product page is encouraged. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial purposes. For information on reprint and reuse permissions, please visit

RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.