In your editorial about Spain’s general election (30 April), your optimism about the capacity of social democratic parties to win elections based on “socially inclusive improvements to the status quo” is based on somewhat dubious premises which might lead to equally dubious conclusions. For example, the Socialist party in Portugal did not win an election in 2015. Indeed, they obtained their second worst election result in 25 years, and were more than four percentage points behind the main rightwing governing party. Instead, they were catapulted into government by the strong showing of two left parties and obliged to govern on a much more radical programme than the one they had campaigned on. And, mirabile visu, they shot up in opinion polls.

The socialists’ partial recovery in Spain and Finland, to which you refer, is prompted by a similar alignment. The indications are that socialist parties can prosper when they run and deliver a more radical programme, against austerity economics and for an enabling state. However, the strong indications are also that they will only do so when pushed or pulled in that direction by strong parties to their left (Corbyn’s Labour may be an exception).

This matters to all of us because if centre-left parties get another opportunity and the best they aim for are some improvements to the post-Reagan status quo, what follows is likely to be very ugly.

James O’Donnell

Sligo, Ireland

• You are right to highlight the trend-bucking success of progressive politics in Spain, but your line about Catalonia having “notably failed” to get behind exiled independence leader Carles Puigdemont could also do with a bit of rebalancing.

The “failure” you cite was due to voters getting behind the other jailed (not exiled) independence leader, Oriol Junqueras, instead, and delivering the first ever general election victory in Catalonia for his party, Esquerra Republicana.

Esquerra have long advocated republicanism, progressive politics and independence from Spain, right back to their beginnings in 1931. This historic result and the reasons for it go to the heart of what happened across Spain on Sunday.

Puigdemont’s party did not poll badly given the circumstances under which he was forced to campaign, but it is a right-of-centre group whose role in what you call the “Catalan separatist crisis” only began in 2013. What happened to his party on Sunday was in line with results nationwide where a huge turnout basically said “no” to the right, extreme or otherwise.

Michael Turner

Barcelona, Spain

• Join the debate – email guardian.letters@theguardian.com

• Read more Guardian letters – click here to visit gu.com/letters

• Do you have a photo you’d like to share with Guardian readers? Click here to upload it and we’ll publish the best submissions in the letters spread of our print edition