Concept · Cognitive Bias: Informal fallacies of ambiguity
Etymological fallacy
Origin: Modern linguistics/logic
Biological Parallel
'Altruism' derives from Latin 'alter' (other)—so helping oneself can't be altruism. This is the etymological fallacy: assuming current meaning must match historical roots. But evolutionary biology redefined altruism as 'behavior that reduces actor fitness while increasing recipient fitness'—regardless of etymology or intention. The term's scientific meaning diverged from linguistic origin. Concepts evolve like organisms: descent doesn't determine current function. Etymology is history, not definition.