defining "national interest"

Recently, a reader noted,

I am having a lot of trouble defining "national interest". I feel like definitions are going to be extremely important for this resolution.

I agree that it's difficult to precisely define "national interest"--and that a good definition is critical for the universal human rights resolution.

Here's my brief attempt to un-muddy the waters.

National interest is usually defined in terms of the actions or policies that advance a nation's economic, cultural, or political standing. In the introduction to Michael Roskin's incisive analysis of the phrase, Col. John Mountcastle offers a decent summary:

The "national interest" is a composite declaration derived from those values that a nation prizes most--liberty, freedom, security. Interests are usually expressed in terms of physical survival, economic prosperity, and political sovereignty. The list invariably expands, and is ultimately shaped by subjective preferences and political debate. As an object of political debate, the concept of national interest serves to propose, justify, or denounce policies.

Roskin himself begins,

The student new to international relations is often at first intoxicated by the concept of "national interest." It seems crisp, clear, objective: what's good for the nation as a whole in international affairs. (What's good for the nation as a whole in domestic affairs is the public interest.) National interest lies at the very heart of the military and diplomatic professions and leads to the formulation of a national strategy and of the calculation of the power necessary to support that strategy. Upon reflection, however, one realizes how hard it is to turn concepts of national interest into working strategy.

The boundary between international and domestic concerns can be fuzzy, since the two are often (or always?) intertwined. Also, it's possible that national interest-seeking is a zero sum game--that one nation's interest rises only as another's falls, or, in other words, we have to define a nation's interest relative to other nations' interests.

Roskin traces the history of the phrase from Machiavelli to Morgenthau and beyond, summing them up in the overall concept that a nation's sole interest (from a practical and empirical perspective) is in preserving its own power. Roskin also notes the difference between vital and secondary interests, which could be important to clarify the debate.

For the LDer interested in this resolution, Roskin's essay is quite useful. Check it out.