>People who like thinking seem to overestimate the power of ideas in shaping the world. My interpretation is that it's probably the typical arrogance of the intellectual letting itself through.

This was not about ideas -- it's was about viewpoint, which has enormous impact in shaping the world.

>For example, there are arguments that the renaissance was a result of the social and economic conditions created by the black death, not the intention of any human actor.

Well, there were other periods similar to the renaissance throughout history, periods not affected by the black death. E.g. the rise of ancient Greece city states (from the so-called "middle ages" of pre-historic antiquity), or the rise of the islamic culture.

And even if the black death was a major factor of change, the way the change took shape is all ideas and viewpoints.

In fact a common argument is that the renaissance was indeed a response to the conditions created by the black death, but the mechanism of change was a change in viewpoints ("let's celebrate life", etc).