The Position of Logic in Aristotle's Divisions of Sciences

One of the subject-matters that Aristotle had raised in his works is the division of sciences. He divides sciences, in different positions of his works, into parts and branches. Aristotle is the first one who articulated logical issues and introduced logic as a science. But in his divisions of sciences seems no name of logic. The question of this article is that where is the position of logic in Aristotle`s divisions of sciences. In this paper, referring to Aristotle works, we attempted to show that logic,by attention to discussions and topics that entails, is one of the parts or branches of the first philosophy and we must consider it as a theoretical science. In Aristotle`s viewpoint, the subject matter of the first philosophy is "being" qua being. But the term "Being" has several meanings; one of them is "being in the sense of true". Aristotle holds that, since all of these senses are synonymous, investigation of them, including the investigation of "true", belong to one science; namely first philosophy. On the other hand logic is the science that is investigating about "true". Therefore logic would be a part or branch of the first philosophy. From viewpoint of Aristotle, logic, at the same time, is an instrumental science. But this instrumentality of logic has no contradictory with the fact that it is a theoretical science. Since what makes a science a theoretical one is the fact that in that science there would be no purpose other than "knowledge"; but what makes a science a non-instrumental one is the fact that in that science there would be no purpose other than "knowledge about the subject matter of that science". Therefore the criterion of "being theoretical" is different from criterion of "being noninstrumental"; and for this reason a science can be a theoretical one, and at the same time be instrumental.