Deduction is a method of thinking in which a new position is derived in a purely logical way from the previous ones, a conclusion according to the rules of logic; a chain of inferences (reasoning), the links of which (statements) are connected by a relation of logical consequence. The beginning (premises) of deduction are axioms, postulates, or simply hypotheses that have the character of general statements (“general”), and the end is consequences from premises, theorems (“special”). If the premises of the deduction are true, then so are its consequences. Deduction is the main means of proof. The opposite of induction.
Sherlock Holmes, the hero of Conan Doyle’s novels, used the deductive method in his reasoning, based precisely on logical thinking and logical conclusions.