The study of the principles of reasoning, especially of the structure of propositions as distinguished from their content and of method and validity in deductive reasoning. A system of reasoning: Aristotle's logic. A mode of reasoning: By that logic, we should sell the company tomorrow. The formal, guiding principles of a discipline, school, or science. Valid reasoning: Your paper lacks the logic to prove your thesis. The relationship between elements and between an element and the whole in a set of objects, individuals, principles, or events: There's a certain logic to the motion of rush-hour traffic. Computer Science The nonarithmetic operations performed by a computer, such as sorting, comparing, and matching, that involve yes-no decisions. Computer Science Computer circuitry. Computer Science Graphic representation of computer circuitry.