reason
noun
°A cause:.
°# That which causes something: an efficient cause, a proximate cause.
verb
°To exercise the rational faculty; to deduce inferences from premises; to perform the process of deduction or of induction; to ratiocinate; to reach conclusions by a systematic comparison of facts.
°Hence: To carry on a process of deduction or of induction, in order to convince or to confute; to formulate and set forth propositions and the inferences from them; to argue.
synonyms: cause, rationale, motive, excuse