header photo

The Laws of Thought

A Thematic Compilation by Avi Sion


The Laws of Thought is an exploration of the deductive and inductive foundations of rational thought. The author here clarifies and defends Aristotle’s Three Laws of Thought, called the Laws of Identity, Non-contradiction and Exclusion of the Middle – and introduces two more, which are implicit in and crucial to them: the Fourth Law of Thought, called the Principle of Induction, and the Fifth Law of Thought, called the Principle of Deduction. This book is a thematic compilation drawn from past works by the author over a period of twenty-three years (1990-2013).


The Laws of Thought can be purchased at and other sales channels.


Please note well: All texts published here are copyrighted (1990-2017), under International and Pan-American conventions. All rights are reserved by the author and publisher, Avi Sion. No text may be reproduced or republished, in any manner whatsoever, without written permission of the author-publisher. Brief quotations are permitted provided they include due acknowledgement of the author-publisher.

© Avi Sion, 1996