Neal Gabler, over a year ago, in the NYT:

The post-idea world has been a long time coming, and many factors have contributed to it. There is the retreat in universities from the real world, and an encouragement of and reward for the narrowest specialization rather than for daring — for tending potted plants rather than planting forests.

There is the eclipse of the public intellectual in the general media by the pundit who substitutes outrageousness for thoughtfulness, and the concomitant decline of the essay in general-interest magazines. And there is the rise of an increasingly visual culture, especially among the young — a form in which ideas are more difficult to express.

But these factors, which began decades ago, were more likely harbingers of an approaching post-idea world than the chief causes of it. The real cause may be information itself. It may seem counterintuitive that at a time when we know more than we have ever known, we think about it less.