To varying degrees, we all rely on what the people around us say, as well as how they respond to what we say, to assess not only what are acceptable utterances, but what is actually true.  This propensity has had its pluses and its minuses.

When we lived in small tribal groups, listening to what other people said about, say, where it was dangerous to go because crocodiles lurked there, this technique enabled us to adapt to our environment far more successfully than we might have based purely on individual trial and error.  But what if you were Galileo, and your extensive observations led you to conclude that the earth moves around the sun?  Having to deal with the generally-accepted belief that the sun is what’s moving could make your life quite a bit more difficult than it needed to be.

Most of us strike some sort of balance between being confident in what we’ve seen with our own eyes and wanting to check whether other people have seen it, too.  This may impede the sharing of novel observations somewhat, but it also limits the extent to which we descend into outright crackpotitude.

With the advent of the Internet, though, we have a new option:  choose to spend the most personally meaningful share of our time and energy in a cyber-world where everyone has the same basic perceptions and beliefs we do.  By making this choice, we get the reassurance of lots of people agreeing with us (so how crazy could we be?), without any of the social corrections that would normally accompany group feedback.  In fact, such groups have a tendency to favor the most extreme statements over the most carefully considered ones.  Socially-cued apprehension of truth has thus flipped from playing a moderating role to one of instigation and flame-fanning.