Such is the terrifying gravitational power of the European Union that it has pulled even Nigel Farage into its orbit. The anti-EU campaigner, who is almost always angry about something or other, made a speech in the European Parliament last week in which he raged at the Brussels authorities for their silence over the repression of the independence referendum in Catalonia. "It is quite extraordinary to realize that this [European] Union is prepared to turn a blind eye," he told fellow MEPs.

Catalan leaders are saying the same thing, of course, but there's a difference. Almost all Catalan political parties support a politically integrated Europe. It is natural for them to look to Brussels, which they see as a sort of supranational capital. Farage, by contrast, has spent his whole career arguing that Brussels should keep its nose out of the internal affairs of its member states.

Listening to him, I marveled at what I think of (borrowing a phrase from one of C.S. Lewis' novels) as the EU's hideous strength. It is now so widely accepted that it is a political union rather than an association of nations that even Farage takes it for granted that it should intervene on the question of Catalan statehood.

In truth, the EU will never side with independentistas. Catalan nationalism, like most nationalisms, is based on the idea that decisions should be taken more closely to the people they affect, and that multilingual and multinational states don't work as democracies. The EU, by contrast, is based on precisely the opposite idea, namely that self-determination is both irrational and dangerous. The very first line of its foundational treaty commits it to form "an ever-closer union."

The tide of history is flowing with the separatists, not with the amalgamators. When the EU was formed in the 1950s, there were 80 countries in the world. Now, there are 200, most recently South Sudan. There are independence movements in every part of the globe — Aceh, Biafra, Cyrenaica, Dagestan, Euskadi, Flanders — but few movements for greater union.

The EU, in short, has every reason to feel threatened by Catalan separatism, as by all separatisms. Once you accept that people are better off living under their own laws, the intellectual case for European integration collapses.

Quite apart from this general objection, the EU has an immediate reason to fear events in Catalonia. At the time of writing, it seems inevitable that the Catalan administration, the Generalitat, will declare independence. Until last week, public support for a complete break from Spain — as opposed to greater devolution of power — was inconstant. Since the deployment of Spanish riot police, it has solidified.

The Generalitat couldn't now back away from independence, even if it wanted to. Public opinion in Catalonia is becoming irresistible. Nor could the Madrid authorities compromise even if they wanted to. Public opinion in the rest of Spain is immovable. What happens when an irresistible force meets an immovable object? One consequence is that Spain's economy, which had been nosing its way up again, will tank. Catalonia can't realistically declare independence unilaterally without taking over its tax collection. Madrid can hardly respond other than by withholding that part of the revenue that Catalonia gets from national taxation. The resulting downturn will reignite fears about the euro crisis, which is the last thing Brussels needs.

From both ideological and practical motives, then, the EU will back Spain, and put pressure on the Catalans to back down — even if that means supporting the troopers with visors and batons as they drag women away from polling stations by the hair. Supra-nationalism will always trump self-rule.

And that is the EU's problem. Modern technology favors smaller units. The Internet, cheap flights, and global rules on technical standards mean that we no longer need to worry about having large domestic markets. The nations in the world with the highest wealth per capita are Monaco, Qatar, and Liechtenstein. Indeed, the only big country to get anywhere near the top of the league is the U.S., which is uniquely ready to devolve power to its constituent states and municipalities.

Is there, even at this late stage, room for compromise? That's what the Prime Minister, Santiago Casares Quiroga, asked General Emilio Mola in a desperate phone call when the Spanish Civil War began in 1936. The answer he got is eerily apt to the present dispute: "You have your supporters and I mine. If you and I were to reach a deal, we should both be betraying our men."

Dan Hannan is a British Conservative MEP.