[nickik]

The idea that libertarians don't understand negative externalities is simple wrong. Maybe you talked to some people in collage who just don't know a lot of economics.

But in actual economics people who one could describe as libertarian politically have been on the forefront of research on externalizes. In fact the most important work on that was done by Ronald Coase. And since then many people like that have worked in that space.

[ohazi]

No, the idea isn't wrong, it simply acknowledges the fact that there are a lot of libertarians who act like this:

http://libertarianpeacenik.blogspot.com/2011/12/big-mouth-li...

You're correct that there are many who are actually reasonable and pragmatic, but it's disingenuous to claim that the other kind of pseudo-intellectual libertarian doesn't exist. They do exist, and they give the reasonable ones else a bad rap.