The death of Fidel Castro brings a tide of anti-travelogues, memories of a crumbling Havana and a degraded people from holidays that realistically can’t have been that bad, otherwise any reasonable person would have cut them short. Prostitution was rife among women and men; there was nothing to buy except black beans and odd socks; and voting, assembling, entering the lobby of a tourist hotel and being homosexual were all proscribed. The life of this 90-year-old is nothing to celebrate; the fact of his death makes it all the more urgent to speak ill of him. And the litany of his abuses is laid down, not really in the service of historical accuracy, but more as a challenge to the left: a dare to lefties, especially those in the baby-boomer generation, to mourn Castro as their hero.

It is a challenge they are unable to pass up. Jeremy Corbyn spoke rather obliquely of Castro as a “massive figure in the history of the whole planet”. It was a fudge and a tautology – anyone whom history remembers is a massive figure in history – but he chose a side eventually, praising Castro’s “heroism”, “for all his flaws”. Ken Livingstone sailed straight for the choppiest waters. Livingstone approaches history like a toddler with a cattle prod, and one can only brace for the needless shock of insult. He delivered: “Initially he wasn’t very good on lesbian and gay rights, but the key things that mattered was that people had a good education, good healthcare and wealth was evenly distributed.” By “initially”, he means “for the first two decades of his rule”; by “not very good”, he means “incarcerated homosexuals in labour camps”; but sure, let’s not get aerated about it. It’s not as if it were a key thing that mattered.

I went to Cuba in the 90s, and the poverty – or, to put it more precisely from the observable data of the tourist, the abject lack of stuff – was unignorable. The museum proudly displaying the shirt in which Che Guevara was fatally shot didn’t look terribly different from the window of Havana’s largest clothes shop, a couple of threadbare shirts stapled to the wall at jaunty angles.

I found the monotony of the tat less depressing than somewhere like Jakarta or even Hong Kong, where vast spires of wealth are flung up right next to a shanty town of shipping containers, or a de facto serf class meets to pray under a flyover. But just because one thing is worse doesn’t make the other OK. Livingstone would doubtless argue that it was because of American sanctions, and not Castro, that Cuba was poor; he would point to the healthcare, the internationalism, the Cuban medics trained and exported to countries poorer still. Critics would come back with the charge that ordinary Cubans couldn’t afford healthcare; and the pharmacies, while elegantly appointed, were empty.

This crotchety back-and-forth misses the point. Castro was an authoritarian. As JFK said of the revolutionaries: “They promised individual liberty and free elections. They promised an end to harsh police-state tactics. They promised a better life for a people long oppressed by both economic and political tyranny. But in the two years since that revolution swept Fidel Castro into power, those promises have all been broken.”

That was 1960; the 50-odd years ensuing, even though they brought a softening on matters like homosexuals and microwaves, didn’t alter the key thing that really mattered; Castro was a dictator.

You can say the principles that drove him were superior to, say, those driving Saddam Hussein; that it’s hard, having won by command and control, to shake the idea that those are the only tactics by which you win; that he’s had a bad rap from western governments that are perfectly happy to turn a blind eye to other, more self-serving dictators. But you cannot make a defence of strongman politics, even if he’s your strongman. You cannot fete Castro as a noble failure while deriding Tony Blair as irredeemable. Principles are like relationships; they don’t mean anything if you won’t put them in order of importance.

Pluralism, democracy and universal rights are the foundations of progressive politics. One man, even if he’s a woman, does not get to govern by force and decree. One oppressed group, even if it’s dentists, is an oppression of everybody. One nation, even if it’s tiny and exports a lot of doctors, is as great an insult to the principles of the left as one dictatorial superpower.

Were it not for the current developments in global politics, this could be left unsaid: leftwing politics could spend happy hours and days in a cloud of whataboutery, like a cartoon of cats fighting. Yet the return of strongman politics to the US, with Vladimir Putin emboldened and Nigel Farage on his way to America to ask for “forgiveness” for the mean things British people have said about Trump, requires a response that is pointed, plain and coherent.

The problem with dictators lies not in what they do: some make trains run on time, and some start wars, and some do neither and some do both, but it would be fruitless to rank them on this basis. The problem is not which groups they victimise – though it is a problem that it will always be somebody, the cornerstone of control being to divide and scapegoat. The problem is not even that strongmen can’t get on with each other, for all the anxiety it brings, waiting for the inevitable confrontation as one immovable, volatile autocrat comes head to head with another.

No, the problem is that the power annexed by one big daddy hasn’t come from nowhere: it is power surrendered by everyone else, whose human destiny is then smothered by their political impotence. Whether you are explicitly denied the vote or simply rendered irrelevant by a winner-takes-all authoritarianism, you are left infantilised and directionless.

The powerlessness of a populace is hard to articulate, and we often describe it by synecdoche: people travelling in the USSR in the 80s would talk about the scarcity of Levi’s, or the fact that East Berliners couldn’t visit the west; we use “women can’t drive” as a shorthand for life in Saudi Arabia. These were or are demonstrable facts, and yet, it’s not the end of the world, is it, denim? What we were really trying to convey was the drabness, the rigidity, the sense of enclosure.

There is no such thing as a modern autocracy, since there can be no positive vision of a future if you have no hand in building it. That’s why life under authoritarian communism always looked so tired; not because the clothes were secondhand but because civic identity was trapped in an inescapable present.

During the first world war the Scottish War Savings Committee produced a poster: Self-Indulgence AT THIS TIME is HELPING THE ENEMY. It’s my new motto: we cannot afford to argue the toss about dictators, parse the difference between the really bad ones and the less bad ones who looked cute in a beret. Refusing to decry dictatorship is a self-indulgence: it is helping the enemy.