From an interview with Tyler Cowen:
The thing about Twitter — is Twitter an engine or a camera? This prevailing view is that . . . I say social media broadly, but Twitter specifically because it’s where the elites are — the intellectual elites, the social elites. The prevailing wisdom on Twitter is that it’s primarily an engine. It’s changing behavior for better or worse. I actually tend to think it’s at least as much a camera. It’s like a giant X-ray machine.
via this interview