Aristotle and the Principle of Non-Contradiction

The principle of non-contradiction (PNC) is both a law of being and a law of thought. Based on the text of Aristotle, the aim of this book is to open a new discussion around the possibility of knowing the PNC by way of intuitive understanding, by recognising its indemonstrability and unhypothetical character and through its fundamentally being the basis of all demonstrative sciences.

Through analysis of contradictory terms and confutational proof, it is possible to find in Aristotle's Metaphysics, book IV the fundamental points by which the PNC emanates from being and protects the unity of thought from contradiction.


The PNC emanates from being because it defines it, and protects the unity of thought because the non-contradictory nature of being is the content of one's thought. Therefore, to deny it, does not mean that reality itself is contradictory by nature, but merely shows lack of education on the part of the person who denies the principle. In fact, the PNC is the highest criterion of significance in its ontological formulation.