logic; reasoning; line of argument
Refers to the method or structure of reasoning, often in debate or discussion. Can be neutral or slightly formal.
彼の論法には矛盾がある。
There is a contradiction in his reasoning.
その論法では説得力が足りない。
That line of argument lacks persuasiveness.
syllogism
evasive debating tactic by quibbling over definitions
dilemma
circular reasoning; circular logic
Compound of 論 (argument, theory) and 法 (method, law). The exact historical derivation is uncertain, but the combination naturally yields 'method of argument'.