Aristotle made a discovery fundamental to all logic by introducing variables. Thus, it was shown that logic is not just a specific doctrine of specific things or terms, but the science of the laws of syllogisms, such as modus ponens or modus tollens, expressed in variables. Studying various judgments, formal logic abstracts from their specific content, revealing a structure common to objects of different content.
Syllogism is the discovery of Aristotle and is the main and most original part of his logic. In the theory of syllogisms, Aristotle defined syllogism and distinguished its types, defined working and non-working types of syllogisms, and established three figures of syllogism. I find it particularly interesting that Aristotle was the first to make reasoning methods the subject of scientific research. He introduced the methods of reasoning as integral formations and not just certain reasoning components. Everything that was done in logic before Aristotle just attempted to understand individual methods and principles without any systematization and unification into a single coherent system. Thus, such concepts as Modus ponens and Modus tollens laid the foundation for understanding the definition of the truth of thinking. Thus, I am amazed at how accurately Aristotle introduced the concepts of conclusions that approach science by the rules of inference, the laws of contradiction, and the exclusion of the third.
Modern logic as an independent field of knowledge arose from such different sciences as philosophy and mathematics. Being indeed a highly advanced concept, modern logic, however, lacks some characteristic philosophical features – it is more straightforward and technical. Modern logic is often called mathematical logic, thereby emphasizing the originality of its new methods compared to those used previously. In this sense, it is of less interest for discussion because it relies on exact sciences and computer technologists and avoids ambiguity. Thus, modern logic is built on artificial language and intelligence, which in itself is rather boring compared to traditional concepts.