LONDON — The euro zone was crumbling, just as he had long predicted, yet Bernard Connolly, Europe’s most persistent prophet of doom, still faced a skeptical audience.

“The current policy of lending plus austerity will lead to social unrest,” Mr. Connolly told investors and policy makers at a conference held this spring in Los Angeles by the Milken Institute, arguing the case that Greece, Italy, Portugal and Spain could not simply cut their way to recovery.

“And one should not forget that of the four countries we are talking about, all have had civil wars, fascist dictatorships and revolutions. That is history,” he concluded, his voice rising above the chortles and gasps coming from the audience and the Europeans on his panel. “And that is the future if this malignant lunacy of monetary union is pursued and crushes these countries into the ground.”

Mr. Connolly has been warning for years that Europe was heading for disaster. As a European Union economist in the early 1990s, he helped design the common currency’s framework, but then he was dismissed after he expressed turncoat views. In 1998, just months before the euro’s introduction, he predicted that at least one of Europe’s weakest countries would face a rising budget deficit, a shrinking economy and a “downward spiral from which there is no escape unaided. When that happens, the country concerned will be faced with a risk of sovereign default.”