logical system, system of logic, reasoning, logical, illogic, metalogic, rationality, rationale, argument, syllogistic, more...

illogic, irrationality, absurdity, unreasonableness, folly

inductive, deductive, abductive, formal, informal, critical, dialectic, more...

formal, same, own, fuzzy, mathematical, symbolic, internal, classical, modal, order, deductive

sound reasoning,   rational thinking,   the reasoning,   reason; rationally,   reasoned thought,   reason by deduction,   assigning logically,   proper reasoning,   good reasoning,   mode of reasoning