Find the exception
"Is there a case where that isn't true?"
Recorded by Plato · Laches 190e–191c; Republic I 331c
Words like 'always', 'never' and 'everyone' break with a single good exception. One clear counterexample tells you the rule needs fixing.
Laches: courage is to 'stay at his post and face the enemy, and not run away' (190e). Socrates: what of the Scythians, who fight 'as much fleeing as pursuing', and the Spartans at Plataea? (191a–c). In the Republic: 'Suppose that a friend when in his right mind has deposited arms with me and he asks for them when he is not in his right mind, ought I to give them back to him?' (331c, Jowett)