"They convince socially, not rhetorically." is an interesting take on the well-known idea of peer-group pressure. Humans have a need to belong, and we'll do it using whatever means are available. It's not just reddit memes, but also even the kind of language scientists use (so their "dominant paradigms" are partly social paradigms). When you laugh at a clever xkcd comic, it's partly a social laugh.

I hadn't thought of it in terms of convincing people - of having arguments and assumptions accepted, often without any opposition, because the conscious barriers are circumvented. Advertising uses this (especially sports-star endorsement). It's not just a sense of "getting it" and belonging/being accepted - it's also values and beliefs being changed.

Incidentally, peer pressure was experimentally confirmed in the famous http://en.wikipedia.org/wiki/Asch_conformity_experiments

EDIT the problem with sacrificing objectivity for a sense of belonging is that you don't see things quite as they are, so you have less ability to make a difference. You can't hack "magic" (there's my in-group reference). But in any group, people will try to conform unconsciously - the stubbornness of Establishment scientists (putatively truth-seekers) is a well-known trope; even here, HackerNews has some cult-like qualities (the "pg cult").

The problem of going the other way is that you sacrifice a sense of belonging for the sake of objectivity - an inhumanly cold choice. And you can't do it fully, anyway.