Social Constructivists are right.

Theoretical debates in International Relations are interesting, but too often the so-called "great debates" are pathetic spectacles in which each sides advances differing views of human nature. As much as it pains the idealists, the in-group/out-group dichotomy (identity) is a necessary insight into how human in fact behave.

However, getting to these valuable insights requires an inter-disciplinary approach, and a certain adventurousness of the mind. And IR scholars are simply going back to the same material.

I stumbled across this nugget in a neuro-science journal. It establishes that empathic feelings (of pain) are stronger within the same ethnic group, and much weaker across groups. It perhaps provides the best explaination as why a liberal, democratic country such as America would remain in Vietnam, and perhaps now Iraq, for so much longer than expected .

To whit, ethnic out-group apathy in International Relations theory. Social Constructivists got it right.