Given the multiplying foreign policy emergencies in the headlines, from the advance of the Islamic State in Iraq and Syria (ISIS) to the face-off between Russia and Ukraine, the subject of Henry Kissinger’s new book, “World Order,” could not be more timely. However the reader may regard the author’s own historical baggage, the book puts the problems of today’s world and America’s role in that increasingly interconnected and increasingly riven world into useful — and often illuminating — context...

Sometimes, in this volume, Mr. Kissinger assumes the role of history professor. In that sense, “World Order” brings his career full circle, back to the doctoral dissertation about the 19th-century statesmanship of Metternich and Castlereagh that he wrote six decades ago at Harvard and that contained all the seeds of his doctrine of realpolitik, now well known.

As he’s done in earlier writings, Mr. Kissinger argues here that there are two main schools of American foreign policy: the realist school (based on national interests and geostrategic concerns, and exemplified by Theodore Roosevelt) and the idealist school (based on a sense of moral mission, and exemplified by Woodrow Wilson).

Mr. Kissinger, renowned as a practitioner of realpolitik, often sounds as if he were mouthing platitudes when he tries to articulate the importance of the idealistic strain in American diplomacy. (“There is a special character to a nation that proclaims as war aims not only to punish its enemies but to improve the lives of their people.”) He is way more persuasive when dissecting the dangers of the Wilsonian urge to “base world order on the compatibility of domestic institutions reflecting the American example” and the perils of failing to analyze “the cultural and geopolitical configuration of other regions and the dedication and resourcefulness of adversaries opposing American interests and values.”

When efforts to export democratic American ideas of order have fallen short, Mr. Kissinger argues, the country has frequently responded by abruptly retreating, resulting in a pattern that has risked “extremes of overextension and disillusioned withdrawal.” Three times in two generations — in Vietnam, Iraq and Afghanistan — he adds, “the United States abandoned wars midstream as inadequately transformative or as misconceived.” With the volatility of the world today, he writes, it is crucial for the United States to stay engaged on the world stage as a “balancer” in places like the Middle East and Asia, especially at a time when Europe seems to be turning inward.

There has always been a dark, almost Spenglerian cast to Mr. Kissinger’s thinking, and he sees ominous signs today of a descent back into a Hobbesian state of nature — in the bedlam overtaking Syria and Iraq, where “no common rules other than the law of superior force” seem to hold; in the spread of weapons of mass destruction and “the persistence of genocidal practices”; and in the Wild West of cyberspace, which has “revolutionized vulnerabilities.”

In fact, he says, we are “insistently, at times almost desperately, in pursuit of a concept of world order,” at this moment in history when “chaos threatens side by side with unprecedented interdependence.”