reason
nounThe basis or motive for an action, decision, or conviction.
nounA declaration made to explain or justify action, decision, or conviction.
nounA fact or cause that explains why something exists or has occurred.
nounA premise, usually the minor premise, of an argument.
nounThe capacity for logical, rational, and analytic thought; intelligence.
nounGood judgment; sound sense.
nounA normal mental state; sanity.
intransitive verbTo determine or conclude by logical thinking.