Both moralists and prudentialists indulge in dreams of a single world. Moralists often think of this in terms of a new world order, a world united by a common set of principles or "norms". Prudentialists typically think of the world growing together through commerce, the movement of peoples, the gradual encroachment of ideas.
The moralist perspective leads naturally to world government; prudentialists are strongly suspicious of Utopian projects, and they have biblical support. As Jesus Christ said: "The children of this world are wiser in their generation than the children of light".
This division of outlook helps explain why it is possible to have two views of Nato's war in Yugoslavia. As you may have gathered, I am a prudentialist. This does not mean I have a partiality for Milosevic. It does mean that I believe that the Balkans, and the world, would be better off if this war had never taken place.
At the moment, the moralists are in the ascendant. Nato's resolve has been vindicated; Milosevic has capitulated. Would-be tyrants have been shown that crime does not pay. Air power works!
But look again: Kosovo has been "cleansed" of 850,000 extra Albanian Kosovars since the start of a war intended to prevent a humanitarian disaster. They will have to be returned to a devastated territory or resettled. The bills for military occupation and reconstruction will be vast.
"Globalisation," says the Prime Minister, "is not just economic. It is also a political and security phenomenon. We live in a world where isolationism has ceased to have a reason to exist. We are all internationalists now. We cannot turn our backs on conflicts and the violation of human rights in other countries if we still want to be secure."
The New Doctrine, Mr Blair said, requires an `important qualification" to the principle of "non-interference in the internal affairs of other countries". Implicitly recognising that the Nato action would not have gained Security Council authorisation, Mr Blair says that "we must find a new way to make the UN and its Security Council work".
He also implicitly endorsed the notion of establishing protectorates in countries that are incapable of civilised self-government. To the historically minded, the New Doctrine bears an uncanny resemblance to the Old Doctrine of ethical imperialism, in the name of which "civilised" countries imposed their "values" on "barbarous" ones.
Mr Blair insists that the New Doctrine is based on "values" not on "territorial ambitions". However, values and interests, he adds, cannot be separated.
The New Doctrine assumes a world that does not exist. It may be the world we would like to exist, and which will come to exist, given time. But right now the "international community" is merely a project - a Western or American project. Insofar as an "international community" can be said to exist, it is clearly not synonymous with Nato. The attempt to convert a defensive alliance into an agent of ethical imperialism is fraught with danger. The New Doctrine unashamedly identifies the good of the world with Anglo-American "values". It has to be stressed that there is no world government responsible for enforcing human rights, nor does Nato have any general mandate to act as policeman.
What we have in the UN Charter are rules designed to maximise the chances of peaceful co-existence - no more and no less.
I do not deny that the international system needs to be revised. But in trying to revise it unilaterally, in terms of universalist principles not universally shared, we - Clinton and Blair particularly - have taken immense risks with international relations, without securing the long- term future of the Kosovars themselves. These risks may turn out well, but we shouldn't count on it.