Garvan Walshe is a former national and international security policy adviser to the Conservative Party. He now runs Brexit Analytica.

Fidel Castro was one of the 20th Century’s most successful practitioners of “post-truth” politics. What other dictator can inspire a Chelsea nightclub where recordings of his interminable speeches are played in the loos?

Perhaps Mao, the Communist who gave his name to the Dublin Chinese restaurant chain that even boasts a take-away offshoot called “Mao at home” (55 Main Street, Donnybrook, since you ask). What next? A Cambodian place called the Pol Pot? Pinot Che’s, a uniquely bipartisan South American wine bar?

There’s a cheap point to be made here about hypocrisy, but that’s a sin of which we’re all guilty enough, and accusations of it form the first refuge of the lazy political opponent who can´t be bothered to attack their antagonist’s position on its merits.

Worse, the quick resort to accusations of hypocrisy debases political debate and creates conditions where it’s easy to imagine that they’re all as bad as each other. False moral equivalence — between the United States and Soviet Union, Israel and Hamas, Russia and Ukraine, Trump and Clinton, Castro and Kennedy — corrupts our judgement.

And judgement, involving experience and feelings as well as rational deduction is far more important to public life than it has in recent times been fashionable to admit. During the period of liberal hegemony that began in 1989, the sheer dominance of liberal ideas made their defenders susceptible to thinking they were, if not quite objectively superior, at least able to set the boundaries of reasonable discussion of political and social matters. Reflection upon the values and impulses that produced these conclusions was thought superfluous by all except post-modernist academics (who usually substituted an unacknowledged Marxist structure for a liberal one) and a tiny number of ex-leftist intellectuals who wrote angry pieces in small-circulation conservative journals in the United States.

They both objected to the consensus of “evidence-based policy” or “political correctness” that they correctly saw substituted for real argument about values and principles. They shared a sense that the liberal consensus had grown complacent and unable to defend itself except through banalities — reinforced by small-l liberal politicians’ tendency to defend their views in terms of “the issues that matter to hardworking families” or “what works”. What works for whom? What does it mean to say that it works? Why should certain things matter and not others?

These questions begged have answers about which we are fated to disagree and our motivations for choosing one answer over another are obscure to our own introspection. How much economic equality is desirable isn’t for instance a question to which there is a single objective answer. It’s the reasons we come to disagree that illuminate more about why we take political positions.

Two seemingly related questions: why do you believe in something, and how did you come to believe it, produce very different sorts of reply. The first is designed to elicit a conventional rational argument (too much redistribution of wealth dulls incentives to innovate). But the second will produce a story (my aunt told me how she and her husband would never have started their business had taxes been higher…). Other people will tell different stories (if it hadn’t been for the health service, my son would have died…) and end up with different political commitments and, crucially, different political identities.

Political beliefs aren’t just arguments, they reflect who we are, and how we want to be seen. Most of us don’t want to be the only gadfly who challenges (though we like to imagine ourselves gadflies in a group of like-minded pseudo-rebels). Nor do we like being reminded of how we gave someone our support when we ought to have known of his crimes. We’d rather hold a false belief than admit we didn’t choose our heroes properly.

Post-truth politics, whether Castro’s or Trump’s, appeals directly to identity. Castro’s apologists find it too painful to admit they’ve raised a feeling of belonging above moral principle.

Expect Trump steakhouses to thrive.