R. G. Collingwood’s declaration that belief in “eternal questions” in philosophy is “merely a vulgar error, consequent on a kind of historical myopia which, deceived by superficial resemblances, failed to detect profound differences” has been vigorously discussed over the last sixty years, thanks partly to its resurrection by Quentin Skinner. But another of Collingwood’s provocative claims has been relatively neglected. If the claims and arguments of classic authors in the history of philosophy provide answers to questions that are not ours, but that are in fact limited to the context of their own time; and if the purpose of history is to illuminate those answers in light of their historical contexts, should historians ask – as Collingwood claimed they “must” – not only “what was So-and-so’s theory on such and such a matter?”, but also “was he right?”? Should the historian of ideas in a world of changing questions nevertheless describe a theory as “false” or “true”, as Collingwood does, or is truth assessment no proper part of the history of philosophy? This essay draws on the full range of Collingwood’s writings, and presents his strongest case for the claim that historians “must” ask “the truth question” about old philosophy.