It's become trendy to support Catalan independence, as was shown by a manifesto released this week by separatist civic group Omnium Cultural. Calling for renewed dialogue between Madrid and the region's pro-independence government, it carries the signatures of fifty international figures, including five Nobel Laureates, Trainspotting author Irvine Welsh and artist Yoko Ono. One wonders whether these signatories genuinely think that they'll command the attention of a government that's already ignored the UN's advice about Catalonia; nevertheless, it's a fashionable "cause célèbre" with which to associate one's name.

Whatever their motivations, these apparently concerned onlookers are right to object to the incarceration of nine Catalan politicians, who in October 2019 received sentences of up to thirteen years for organising the 2017 independence referendum. Yes, they broke the law in holding a vote declared illegal in advance by Spain's Constitutional Court; but a hefty fine or a lengthy expulsion from politics would have been more in proportion to their crime than over a decade behind bars. After all, former Catalan president Artur Mas, who in 2014 also orchestrated an illegal independence referendum, was fined 36,500 euros and banned from public office for two years, not thrown in a cell.

In posing a series of complex questions, the manifesto also makes you consider both sides of the Catalonia argument. It says, for example, that Madrid denies "the right to self-determination" of Catalonia. Is this a "right"? It is according to the second section of Spain's 1978 Constitution, but anti-separatists point to the same sentence of that document, which also asserts the "indissoluble unity of the Spanish Nation".

The right to "self determination" is not the same thing as the right to independence, and Catalonia already has a great deal of the former. Along with the Basque Country, Spain's wealthiest region enjoys substantial powers of self-governance and autonomy. Furthermore, in his recent budget deal with the pro-independence Catalan Republican Left, Pedro Sánchez enhanced Catalonia's privileged status even further, giving it more money and tweaking Madrid's tax laws in Barcelona's favour. The Socialist leader has also signalled his openness to the dialogue for which the manifesto calls, although always with the "Constitution in hand". Talks started in February, but were halted by the outbreak of Covid-19.

The signatories want Catalans to have a legal vote on divorcing Spain, and cite the precedents of Scotland and Quebec, which held independence referendums in 2014 and 1995 respectively (both narrowly returned "No" votes). But neither of those plebiscites, it is crucial to remember, required fundamental constitutional reform in order to be held. In other words, it's a lot more complicated than the supporters of the pro-independence manifesto - keen to lend their name to a trendy cause - would have you believe.