“ A lie can travel halfway around the world before the truth can get its boots on” has been a cliche for a hundred years. I don’t think internet social networks are a difference in kind, but they probably are a difference in degree.

Agreed but I said "apart from scale and reach". The point I was trying to make was that people have always found it fairly easy to believe non-credible sources. In this sense, social media is not qualitatively different. Only quantitatively different.

A large quantitative change is indistinguishable from a qualitative change: what's the difference between light rain and a flood, between some small waves and a tsunami?

What I meant, is that in the eyes/ears of those RECEIVING the information (and believing it uncritically), there's no difference. People have always had a predisposition to uncritically accepting information from those "in the tribe", whether that be extended family, or an internet echo chamber. Presumably this was a survival optimisation. Trust those "close", and distrust "others".