I propose that a candidate for this second theory would be a
neurological theory, possibly examining the connections between
activity in (for example)
the Broca's and Wernicke's areas of the temporal lobe that seem to
be heavily involved in linguistic manipulations and "logical rigor"
and
the regions in the brainstem (and limbic system?) involved in
territoriality and aggressiveness.
Carefully distinguishing between the future fortunes of a meme and
the future fortunes of oneself is a hallmark of civilized behavior,
but I think it takes time for us to become civilized (people aren't
born civilized), and formalized argumentativeness may be a form of
physically-nonrisky display combat (common among animal species)
that helps us learn how to use language and how to pick apart and
analyze ideas.
Obviously, since the second theory you are requesting is a
neuropsychological one (or at the least the best candidate I
can come up with right now is) the matter will be open to
dispute for at least another few years. ;)
-- Eric Watt Forste ++ arkuat@pobox.com ++ expectation foils perception -pcd