Maybe Aristotle was the first philosopher to say that, sometimes, the truth will set you free only if it pisses you off. Indignation at injustice, anger at exploitation, outrage when the innocent are defiled and victims are insulted: there are times when boiling blood is a sign of good health.

Anger was everywhere in classical Greece. Volcanic anger moved hero and anti-hero alike. In epic poetry and on the stage, anger was explored. It was cathartic and could help politics turn a new page. But it could also be tragic, self-destructive, a form of madness that could lead a mother to kill her own children.

Anger in politics is all around us today. From India to Turkey, from Poland and Hungary to Brussels, from Brexit to Trump. In Malta, there’s fury at corruption, rage against the people who expose corruption, and internecine rage within the opposition and civil society, with anathemas flying in every direction.

Aristotle said anyone can get angry but few get it right. It takes skill to know when to get angry, with whom and how much. Yes, skill. A political skill, given that, for Aristotle, if you got your ethics right you were on the way to getting the politics right, too.

We badly need more of that skill in Malta, right now. Our predicament can be summed up in two paradoxes, two sides of the same coin.

Ordinary people are being robbed blind but the majority’s anger is turned against those who denounce the pillaging. How come? In part, because many of those denouncing the corruption —how it destroys ordinary people’s aspirations — allow themselves to be plausibly portrayed as elitist.

Some of this misplaced, misdirected and badly expressed anger is a result of our forms of communication. Troll armies are easier to organise on Facebook and it’s tempting to return insult and verbal violence with like fire.

The business model of blogging makes outrage attractive, and besides, if you’re an effective political blogger you’re probably someone else’s target, under fire much of the week, and it’s easy to feel justified in giving as good as you get.

To be clear and avoid all misunderstanding: Some truly scandalous things are being said and done by the government, which dominates the means of communication. Its narrative is difficult enough to combat. It will paint its opponents as elitist, and itself as a victim, no matter what civil society says and does.

Corruption and intimidation deserve to be addressed with anger. But there are ways and ways, and some fall into the trap of the demagogues in charge.

Political struggle is partly about the power to define the opponent and make that definition stick.

Demagogues thrive under two conditions: when they can portray anger as hate, and when they can divide society into Us vs Them.

If cronies in charge can make civil society’s anger at corruption seem like hate, the cronies win. If they can portray liberals as elitist snobs, against real upward mobility, they win.

The record around the world is clear. What demagogic populists everywhere strive for, strategically, is to transform their liberal opponents into the populists’ mirror image: to treat the liberal opposition as so foreign and so other, that the opposition replies in kind, excommunicating anyone who doesn’t pass the most stringent purity tests.

The record from around the world is also clear that the way to defeat demagogues is to hold your nerve, and continue to occupy the moderate centre. Moderate doesn’t mean weak. It means standing firm for the rule of law and standing firm in embodying the values of liberal respect.

How can we tell if we’re angry or descending into something closer to contempt or hate? Anger is indignation at scandalous behaviour. If it’s expressed as disdain for someone’s essential identity — their accent, their tastes, their family or class — then it can plausibly be portrayed as hate.

In principle you can argue for respect for someone’s fundamental human rights, while mocking their culture and status. In practice, no one will believe you mean it, because they associate respect with civility, and they’ll be afraid of what you’ll do if you ever have power over them.

Civil society — people power — will never succeed against a corrupt ruling class if that regime can persuade the majority that its opponents are a sect, who divide the world into black and white, who’s with them and who’s against them. Right now, in Malta, that strategy is succeeding, with parts of civil society accepting the Us vs Them division promoted, for propaganda purposes, by Joseph Muscat and, now, Robert Abela.

Liberals always lose at the name-calling game. Even if they win elections, they will sabotage their own political ideals. The liberal ideal is one where political difference doesn’t create victims. Liberal ideals are sabotaged by demagogic rhetoric.

It’s one thing to argue — as I, for one, often have — that a liberal society is one where there is great latitude for offensive speech. Of course it is, and the right to free speech includes the right to be offensive.

But if your aim is to bring about that society, then you go about it the wrong way by insulting the very people you need to support that aim.

That’s the problem with the wrong kind of political anger. It plays into the hands of those who truly deserve your anger. It blinds you and drives you mad. It sabotages your better self. Instead of energising a new politics, it consumes your movement.