What Does 'Realism' Mean in Foreign Policy?

There was a good debate on this subject earlier this week between Jonah Goldberg and Peter Beinart:

watch video

Here's my own attempt to untangle the thicket of confused definitions which surrounds this issue:

Realist (capital R) politics is not the same thing as realistic politics.

Realism is a specific worldview and resultant foreign policy which holds that nations act purely in their own self-interest and can be deterred, and balanced off against each other, on that basis for our own self-interest (as in the architypical Realist view of co-operative dictators: 'he may be a bastard but he's our bastard').

This Realism defines itself in opposition to Idealism, seen as a worldview which is utopian and unrealistic, i.e. idealistic in the pejorative sense

but Idealists believe they're idealistic in a realistic sense of having achievable ideals, and think Realists are cynical and unrealistic insofar as their philosophy denies progressive improvements in the international order are achievable (though not in the sense that what they wish to achieve with crude power plays can't actually be achieved).

..which is why it's not oxymoronic for Idealists to counter by speaking of realistic Idealism, or even of idealistic Realism insofar as there are areas where they believe over-confident Realists don't in fact have realistic analyses, goals or strategies.

But given the above, what is contradictory is for idealistic liberals to adopt the label Realist, as some have recently done, rather than merely proclaim themselves realistic.

Similarly there are problems with conservatives adopting Realism, because conservatives generally see international relations as more complex than people acting purely to gain, hold onto, and extend their power base, although that's naturally a common motivation among those who tend to rise to positions of power..

but conservatives also recognise the important motivating roles played by such things as culture, sense of national honor, and ideology (how to explain the Nazis otherwise?) as a consequence of their rich understanding of human nature and the many factors which bring out its best and worst tendencies. (also, how to explain the very Idealism you're vigorously defining yourself against without also acknowledging it as a viable foreign policy postition not based in crude self-interest when you deny the possibility of such foreign policy positions being held by other nations?)

but it would still be reasonable to describe such conservatives as Realists of a kind because they likewise believe that nations act in their own self-interest and in the folly of idealistic solutions to international strife; they just have a broader understanding of the many different facets which comprise 'national interest'.

related: Anatole Levin and Anne-Marie Slaughter debate 'ethical realism'