On Leibniz’s Two Principles Of Reasoning

Hailed as an "encyclopedic" scholar,Leibniz introduced two principles of reasoning,the principle of contradiction and the principle of sufficient reason,in his book "The Monadism",and regarded the two principles of reasoning as the basis for the construction of his philosophical logical system of thought.The ideological origin of the two major reasoning principles can be traced back to the ancient Greek period,the idea of the contradiction principle originated from the predecessors,especially Aristotle’s thought on the laws of logic,and the idea of the principle of sufficient reason originated from the law of cause and effect.The principle of contradiction includes the law of contradiction,the law of identity and the law of exclusion in traditional logic,and the law of sufficient reason in traditional logic is a derivation of the principle of sufficient reason,indicating that the premise and conclusion have the general meaning of logical necessity.Leibniz found that in reasoning,it is not enough to rely on the principle of contradiction,which applies only to partial truths,and that knowledge acquired according to the principle of contradiction,while reliable,is not necessarily meaningful.He therefore proposed the principle of sufficient reason to supplement the inadequacy of the principle of contradiction.Furthermore,Leibniz formed a unique theory of truth by analyzing propositions and dividing truths according to two major principles of reasoning.Then,in order to fully explore and refine the theory of truth,Leibniz proposed the theory of possible worlds.In realizing the idea of a universal language for the first time,Leibniz initiated the logical mathematization on the basis of the principles of contradiction and sufficient reason.Leibniz did not clearly elaborate on the relationship between the two principles of reasoning,which also triggered a great discussion in the academic circles,and the study of the two principles of reasoning either severed the connection between the two to a large extent,or focused on the analysis from a philosophical point of view.The principle of sufficient reason is ostensibly intended to compensate for the inadequacy of the principle of contradiction,but in fact Leibniz regarded it as an important principle of reasoning alongside the principle of contradiction.Through the method of disproof,it can be shown that the two principles of reasoning are both independent and mutually influencing each other in Leibniz’s logical thought,and the two are closely related.The two principles of reasoning have a profound impact on the development of logic and philosophy,and promote the development of subcompatible logic,mathematical logic and inductive logic.At the same time,the two principles of reasoning provided new methods for the study of later philosophies,and had an important impact on analytic philosophy and humanistic philosophy.In addition,the two major reasoning principles have important methodological significance in people’s daily life and scientific thinking research.