So why do people leave? How do they change their minds? Different ways, I think. There is the lightning conversion, the stunning realisation that everything you’d previously thought is wrong, and everything you’d thought is wrong is right. Today that sometimes seems to happen to individuals who are raised in restrictive religious environments and who find themselves exposed, accidentally or otherwise, to the scepticism and relativism of the secular world — though obviously the road to Damascus can lead in the other direction, the direction of faith. There is the opposite experience: the feeling not that you have changed but that your tribe has — something that many are feeling with respect to one or other of the major political formations. There is the slow accretion of countervailing information that eventually leads (gradually, then suddenly, like Hemingway’s bankrupt) to a change in one’s view of reality, the way a scientist changes their mind.

But for me the most important way, and not just because it is the one I find most salient for me, is this. You change your mind when you consent to stop ignoring things you know full well but do not want to think about — things that you push to the edges of consciousness, or all the way out. Few of us are scientists. We do not gather facts through careful, ordered processes; we aren’t compelled to make our arguments in formal terms in front of expert referees. Our thinking is less about finding the truth than about making ourselves feel good. And so when we encounter a countervailing piece of information, an uncomfortable truth, we dismiss it as an anomaly, or as not undermining the general point, forgetting the previous “anomalies” and not regarding how they might together utterly destroy the point.

To overcome such a block, to look in the face an unwelcome reality, is first consternation, then liberation. Anyone who’s been in therapy will understand this. The truth always feels good, on a certain level, just because it is the truth. It relieves us of the psychic stress it costs us to resist it.