John Gray is an academic British political philosopher who has gone through several political mutations before emerging as a dedicated environmentalist, a self-styled saver of the planet. His new book, “Black Mass” (Farrar, Straus and Giroux, 210 pages, $24), is an unsatisfying hybrid: a study of how the complex history of political messianism can mimic some of the mythic patterns and processes of transcendental faiths, mixed with leftist polemics against neoconservatism so crude that they might have strayed from the “mind” of film maker Michael Moore. Even the conceit that the hawks would be better described as “neo-Jacobins” is derivative, since this reviewer employed it in a comment in the Guardian during the 2003 Iraq invasion.

Since Mr. Gray has undertaken no original research in the historical fields he alights on, he is unable to interrogate any of the major methodological assumptions he has lifted from the scholarship of others. As with other interlopers from different disciplines, who think it is enough to read half a dozen history books on Communism or Nazism before pontificating about the “moral history of humanity,” one’s first reaction as a professional historian is to ask, why bother with the middle man? Since Mr. Gray is not a professional foreign correspondent either, his thoughts on, say, the Middle East, lack any sense of human immediacy. An air of academic dessication dogs the whole enterprise, despite some pithy provocations. Without exploring how polyglot scholars — from Eric Voegelin to Raymond Aron to Jacob Talmon — have used actual research to explain the survival of religiosity, now camouflaged, in our post-secular age, the monoglot Mr. Gray simply assumes this insight is correct. He then gives reduced — in the sense of sauce — versions of how Communism and Nazism sought to achieve heaven on earth by consigning millions to their respective versions of hell. His own contribution is to insist that western economic and political liberalism is just another delusional attempt to bring about a utopian “End-Time” — based on democracy, free markets, and human rights — in the teeth of mounting resistance from China, Russia, and Afghani or Iraqi insurgents. The dangerous virus of progressive interventionism, he writes, has spread from American neo-conservatives, often with Trotskyite backgrounds, to tough liberal-leftists, of whom Britain’s Tony Blair is the most prominent, and a major villain in Mr. Gray’s view. He writes “Liberalism has been as utopian as other philosophies in positing a kind of ultimate harmony as an achievable goal.” This view was expressed much more cogently by the late Maurice Cowling, one of many great scholars missing from Mr. Gray’s notes and bibliography. When he sticks to writing about Plato, Hobbes, or Spinoza, each of whom he knows about as a professor of political science at the London School of Economics, Mr. Gray is on familiar ground, but as soon as he strays into contemporary international affairs, his opinions — for that is all they are — have no greater value than those of a bricklayer or plasterer. He manages to be categorical about events that shift from week to week. Some of his verdicts already seem stale since he continually speaks about coalition “defeat” in Iraq, a view that is by no means self-evident during the current American surge.

No difficulty or doubt affects Mr. Gray as he asserts that, say, the economic turbulence of Weimar Germany, or the existential shock of the attacks of September 11, 2001, in America, led to the totalitarian/authoritarian reconstruction of their political systems. According to Mr. Gray — and New Yorkers may wish to steady your spoons over the boiled eggs — “the US has suffered a loss of freedom that has no parallel in any mature democracy.” Crassly, the Methodism of President George W. Bush is compared with the messianic mania of Iran’s Mahmoud Ahmadinejad, the strange wee Holocaust denier who wants to eradicate Israel. Mr. Gray also absurdly accuses America of operating a “concentration camp” at Guantanamo, a line I last heard from leftist German supporters of the Provisional IRA who compared Britain’s Maze internment camp with Dachau.

“Black Mass” might have been an interesting essay on the stubborn intractability of the wider illiberal world in the face of the bumptious optimism of proconsuls such as John Bolton or Ken Adelman. Instead, the book is a rehashing of every single leftist “take” on the war in Iraq — from the role of Big Oil to the influence of the long deceased Chicago thinker Leo Strauss. His conclusions consist of a series of Jeremiah-like lamentations on the effects of overheating and overpopulation on our planet, intertwined with a vaguely-expressed plea for greater realism in foreign relations. (He begins this anomalous appeal by acknowledging the fact that most people do not live in democracies and may even welcome the existential security of tyrannies.) This is in turn overlaid with further pretentious guff about how we should free ourselves from “narratives” of progress by learning from Buddhists and Hindus. Unfortunately, the people who have guidance of states in dangerous times cannot luxuriate like Proust over his tea and petites madeleines. Somehow, one cannot see “Black Mass” as required reading in the State Department.

Mr. Burleigh’s books include “Earthly Powers” and “Sacred Causes,” both published by Harper Collins.