Logic is the study of the methods and principles used to distinguish correct from incorrect reasoning.

“All our lives,” as Edith Watson Schipper wrote, “we are giving and accepting reasons. Reasons are the coin we pay for the beliefs we hold.” Yes; but reasons given are not always good reasons. With reasoning we produce arguments, some good, some bad. That can be formulated in writing or speech. Every argument confronted raises this question: Does the conclusion reached follow from the premises used or assumed? There are objective criteria with which the question can be answered; in the study of logic we seek to discover and apply those criteria.

We examine arguments of many varieties, in many spheres arguments in science and religion, ethics and law, politics and medicine, commerce and sports, and arguments arising in everday life. Whatever the subject or content of an argument, the logician is interested in its form and its quality. Does the argument do what it purports to do? If asserting the premises of some argument to be true does warrant asserting the conclusion also to be true–then the reasoning is correct; otherwise it is incorrect.