The Oxford dictionaries named “post-truth” as their 2016 Word of the Year. It must sound alien to scientists. Science’s quest for knowledge about reality presupposes the importance of truth, both as an end in itself and as a means of resolving problems. How could truth become passé? For philosophers like me, post-truth also goes against the grain. But in the wake of the 2016 U.S. presidential election and the seemingly endless campaigns preceding it, author Ralph Keyes’s 2004 declaration that we have arrived in a post-truth era seems distressingly plausible.