argument argument by analogy argumentum ad baculum argumentum ad captandum argumentum ad hominem assailability bad case bad habit begging the question besetting sin blemish bug catch chink circular argument claptrap crack crowd-pleasing argument defect defection deficiency drawback empty words failing failure fallacy fault faute feet of clay flaw foible formal fallacy frailty heel of Achilles hole hysteron proteron imperfection inadequacy infirmity insincere argument kink little problem logical fallacy material fallacy mere rhetoric moonshine moral flaw non sequitur paralogism penetrability petitio principii philosophism pregnability problem pseudosyllogism rift shortcoming snag soft spot solecism something missing sophism sophistry taint verbal fallacy vice vincibility vulnerability vulnerable place vulnerable point weak link weak side weakness