German philosopher Jürgen Habermas has accused Angela Merkel of undermining the European Union and its common currency by putting investor interests above democratic concerns and thus prolonging the Greek crisis.

European leaders had degraded themselves in the crisis, he said.

Rather than correcting euro shortcomings exposed in the crisis by launching a push for full political and economic union, he said they were now acting like “zombie” creditors.

“The currency union will remain instable as long as it is not complemented with a banking, fiscal and economics union,” wrote Prof Habermas in the Süddeutsche Zeitung.

“If we don’t want to declare democracy as mere show, this means expanding the currency union to a political union.”

The Bavarian-based philosopher, a long-term critic of Germany's bailout strategy, said Berlin's failure of political courage to complete the single currency's structural deficits had forced German and European courts, as well as the European Central Bank, to bend their mandates to breaking point to save the euro.

That Europe was once more facing an existential crisis, he said, was "because already in May 2010, investor interests were more important for the German chancellor than debt relief to reform the Greek economy".

As a result the hard-left Syriza government and its European creditors were now “blathering like parrots” that they each had a - contradictory - democratic mandate.

It was, Prof Habermas wrote, like an arrogant novice locked in a “grotesque exchange” with a derogatory superior.

The “unintended comic quality” of their respective nationalist perspectives made clear to all what is lacking in Europe, he said: a central European forum where citizens can agree on decisions about issues of far-reaching consequence.

Talks in Brussels were at the brink, he argued, because each side blamed “not the deficits of the processes and institutions, but rather the erroneous behaviour of their partner”.

Similarly, the Greek crisis had come to a dead end because of a conscious failure of all sides to see the political wood for the economic trees.

In particular, Chancellor Angela Merkel was clinging to the fiction that Greece would require no further debt relief, he said, because of an uncertain Bundestag majority for further Greek aid.

“But wrong-headed politics must, in light of its counterproductive consequences, be revised one way or the other,” he wrote.

Prof Habermas didn't just blame Germany for pursuing "fantastical" Greek debt demands, he reminded his German readers of their country's role in Greek history.

Or, to be precise, he pointed to the legacy of King Otto of Greece, born into Bavaria’s Wittelsbach royal family and installed as a 16 year-old monarch in 1832 to modernise the country -- but deposed three decades later.

“It’s clear the Wittelsbachers didn’t build up a functioning state,” suggested Prof Habermas, “however such difficult circumstances cannot explain why the Greek government makes it difficult even for their sympathisers to recognise the line of logic in their erratic behaviour.”

To balance out his attack on Berlin, Prof Habermas took issue with the Syriza government, saying it wasn’t clear whether “ignorance or lack of experience” was to blame for their failure to present a Keynesian alternative programme to the “Merkellian medicine” of “neoliberal impositions”.

Instead of promising far-reaching plans to address institutional reform, corruption and tax evasion, he accused Syriza of falling back into a “moralising ... blame game”.

The weak performance of the Greek government did nothing to justify the “degradation of politics to market conformity” in the Merkel era.

It did, however, go some way to explaining "the chuzpah with which German government members ... deny their political co-responsibility for the appalling social consequences of neoliberal austerity programmes they accepted as influential European Council members".

He traced this cause-and-effect disconnect back to Merkel’s insistence that the IMF join Europe’s bailout programmes.

This, he said, had allowed EU politicians to ape the fund’s “rule-bound actor” approach in dealings with Athens.

Germany had not just disowned the consequences of the demands it made of Greece - an explosion in social misery. Berlin had forgotten the far-sighted decision of its own creditors in 1953 to forgive about a half of its war debts.

That this was “morally embarrassing” was, Prof Habermas argued, now beside the point.

The time had come for politicians to stop hiding from their voters and back a new effort to complete the struggling, incomplete currency union.

“It is citizens, not banks, who must have the last word in questions of far-reaching European significance,” he wrote.

Amended on June 23rd. An earlier version of this text suggested Prof Habermas saw a link between Bavarian-born King Otto of Greece and the strategy of today’s Greek government in the eurocrisis. This is not the case and has been corrected.