Post-truth: a guide for the perplexed

he 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 US 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. Post-truth refers to blatant lies being routine across society, and it means that politicians can lie without condemnation. This is different from the cliché that all politicians lie and make promises they have no intention of keeping — this still expects honesty to be the default position. In a post-truth world, this expectation no longer holds. This can explain the current political situation in the United States and elsewhere. Public tolerance of inaccurate and undefended allegations, non sequiturs in response to hard questions and outright denials of facts is shockingly high. Repetition of talking points passes for political discussion, and serious interest in issues and options is treated as the idiosyncrasy of wonks. The lack of public indignation when political figures claim disbelief in response to scientific consensus on climate change is part of this larger pattern. 'Don't bother me with facts' is no longer a punchline. It has become a political stance. It's worth remembering that it has not always been this way: the exposure of former US president Richard Nixon's lies was greeted with outrage. One might be tempted to blame philosophy for post-truth. Some of us write about epistemic relativism, the view that truth can vary depending on the context. Yet relativism is itself relative. An extreme relativist might hold that the truth varies from person to person, a position that does not leave much room for debate. But more rational positions can also involve at least a modicum of relativism. In a sense, even eighteenth-century philosopher Immanuel Kant's quite sensible contention that we can never know what things are like 'in themselves' — independent of how our minds format what we perceive — is a relativistic position. It implies that what is true of the world for humans is probably different from what is true for a fly. Entomologists would surely agree. More radical forms of relativism …