Deduction is defined as the method of reasoning by which conclusions must follow from certain assumptions , principles, or concepts. If there are five people in a room, for example, one can deduce that there are also four; or if it is assumed that everything in nature exists for a purpose, then one can conclude that humans, too, exist for a purpose. Deductive reasoning proceeds from the general to the particular. It is the use of a general statement as the basis for reaching a conclusion about specific examples. Deduction is also known as Deductive reasoning.