What explains the ad hominem rampant in online discourse?
anamax: Many people live in like-minded tribes.  One of the tribal activities is slagging "the other".  In fact, there's often a competition along those lines.  However, since said other isn't present, they're really engaging a caricature that they invented.  As a result, their arguments are weak.When they run into said other online, they're basically cued up for battle.  However the reality doesn't behave like the caricature, so all of winning arguments fall flat.  Rather than acknowledge that they're lame, they lash out.