Deductive method is a way of drawing conclusions by reasoning from general statements using rules of logic. The process of reasoning is called deduction, and the statements from which the process begins are known as premises. The conclusions of deductive reasoning are referred to as valid, rather than true, because there may be a difference between that which follows logically from the premises and that which really is the case. For example, if we apply deductive reasoning to the premises that “All Greeks have beards” and that “Zeno is a Greek,” we may validly conclude that “Zeno has a beard.” But it is not necessarily the case that Zeno has a beard because at least one of the premises—that all Greeks have beards—is not really the case.
Mathematics and logic make extensive use of the deductive method. Thinkers combine deduction with induction to make many scientific discoveries and other contributions to knowledge. Induction is the reasoning process by which a person starts from particular experiences and proceeds to generalizations (see Inductive method).
See also Logic; Science (Mathematics and logic).
