Abstract

The principle of identity is one of the three basic principles of reason on which classical logic rests. The other two basic principles of reason are principle of noncontradiction and of the excluded middle. These principles were accepted almost unquestionably until the beginning of the twentieth century. Therefore, classical logic, which adhered to these principles, continued to prevail. Today, however, one of the most interesting debates in the field of science is whether these fundamental principles on which classical logic rests can be seen as necessary and invariable truths. With this discussion, a logic emerged in the twentieth century, rejecting the basic principles of reason. In this study, we will examine the logics -non-reflexive logics- that rejects or limits the principle of identity, from which the other two principles of classical logic are derived. First of all, we will talk about the origins of non-reflexive logic. Next, the basic assumptions of the identity principle of classical logic will be discussed. Finally, we will discuss the reasons for which non-reflexive logic rejects or limits the principle of identity, in other words, which assumptions of the identity principle are considered problematic.