There are plenty of reasons why conflict is at a low ebb. The main one is the evaporation of the Cold War, the historic 50-year-long struggle between Russia and America. That has left the US, like Britain at the end of the Napoleonic Wars, as the sole power that is able to exert its influence wherever and whenever it wants.
Since Immanuel Kant and Adam Smith, liberals have hoped that trade and investment would bring perpetual peace by making every state more familiar and inter-dependent with its neighbours in a family of nations. As anyone who has just spent two days locked inside with their nearest and dearest will testify, familiarity and proximity do not always help to ensure harmony. But there is some truth in this idea: the European Union and regional trading blocks around the world are removing barriers and bringing countries closer together in the pursuit of greater material wealth.
But it is at this point in the argument that the optimism pales. We do not have a single formula for perpetual peace, and (like Tolstoy's unhappy families) all wars are unalike, with widely varying causes which are not susceptible to a single answer. There are plenty of reasons to think that, viewed historically, this Christmas is about as peaceful as humanity gets. The next 12 months may well be more violent than the last. The world is less prone to war, but there is not a lot of goodwill around; as City analysts would put it, downside risks abound.
The Middle East is the main cause for concern. As in Northern Ireland, a peace process has bloomed and then wilted. It is now in great danger of fading altogether. There is little goodwill between the Palestinians and the Israelis since the election of Prime Minister Benjamin Netanyahu threatened to destroy the Oslo process.
The Gulf, too, is a volatile place with both Iraq and Iran unhappy at the status quo and eager to disrupt the US-led regional framework that emerged in an ad hoc way from the Gulf War. And the coalition behind the United States in the region is as shaky as ever, as demonstrated yesterday by France's decision to withdraw its planes from the skies over Northern Iraq.
China is the other blip on the radar. It is a country undergoing fantastically rapid economic and social change, with an unsteady political apparatus that sometimes seems barely able to contain what is going on within its borders. China's growing nationalism may be contained, and its efforts to resolve its border problems with India and Russia are laudable. Nor is the drum-banging in the US over the "Chinese threat" particularly helpful. Nevertheless, as last year's confrontation with Taiwan showed, there is always the potential for China's many disputes with its neighbours to escalate.
What the peace reminds us of, however, is that war is not an organic necessity in any part of the world. The presence of rising and falling states, border disputes, economic and environmental tension and ethnic conflict, can be handled, or contained, with hard work and ingenuity. Goodwill cannot be engineered, but peace can be held even where fraternity runs thin.
That must not stop us seeking room for improvement. Conflict prevention through diplomacy and confidence-building measures can function if it is given time, and that means giving it greater priority. It is cheap and it can be effective, which should commend it to any state that has an interest in maintaining peace. Secondly, peacemaking (something which was relatively successful in Bosnia) can work if it has the backing of the UN and the main military powers. Thirdly, rapid and effective rebuilding of infrastructure and civil society after a conflict is vital. That task is proceeding too slowly in Bosnia, but it is happening. We are learning. The last seven years have taught us a lot about war and peace.
All of these lessons apply to the main Western powers, those with the military punch, diplomatic strength and economic clout to fight wars or to stop them if they want to. But they are also lessons for one man who is doubtless enjoying the festive season a little more than most after getting just what he wanted for Christmas. Kofi Annan, the new United Nations Secretary-General, has plenty of experience of keeping the peace from his years as an international civil servant. He is well-equipped to guide the organisation principally charged with maintaining the security of the whole world at such an important time. Let's hope that he can take us through another, still more peaceful year ahead.