Undismal scientist.

John Kenneth Galbraith: His Life, His Politics, His Economics, by Richard Parker (Farrar, Straus and Giroux, 832 pp., $35)

MIDWAY through this doorstop of a biography, the narrative is interrupted by a raft of photographs. There is John Kenneth Galbraith stooping--always stooping, as if his great beak of a nose were dragging him down from Olympian heights to a more mortal level--to speak with Jackie Kennedy and JFK; with Jawaharlal Nehru and George McGovern; with Jimmy Carter and Julia Child; with Bill and Hillary Clinton. The world has changed, these photographs seem to suggest, but Galbraith has been a hawk-nosed constant, casting a lengthy patrician shadow over the decades-long waning of the American liberal establishment.

Except that Galbraith is not really a patrician, by birth or breeding. Raised a Scottish-Canadian farmboy in rural Ontario, he spent his undergraduate years at an obscure agricultural college and found his way into the New Deal brain trust and the Ivy League half by accident. And the strangeness of this fate, in which his older identity as a rural nobody was subsumed into a variety of unexpected roles--bestselling public intellectual, ambassador to India, confidant to presidents and presidential candidates--would seem to have the makings of an acute and distinctly American psychological drama, rich in mystery and contradiction.

Unfortunately, though Richard Parker's biography runs for over 800 pages, it's only in the photographs that the contradictions, public and private, of Galbraith's unusual life come into focus. What Parker has given us, as his title suggests, is an intellectual biography, not an intimate portrait: Galbraith's relationship with his wife and children, his famous friendships (with this magazine's founder, among others), and his affinity for celebrity and power are all touched on but rarely analyzed. Parker is more interested in his subject's books and times, you might say, than his life and times, and while the books are interesting and the times fascinating, there is an absence at the center of the biography, a place where Galbraith withdraws from his biographer's gaze, or where Parker fears to tread.

Instead of intimacy, Parker favors broad sweeps and wide canvases, in which Galbraith's life opens out into the story of the American century, and particularly the nation's various political and ideological conflicts. This approach has its advantages: Parker writes cleanly and fluidly, and his subject--an idiosyncratic Keynesian who became FDR's price czar, worked for Henry Luce's Fortune, took part in the Strategic Bombing Survey, wrote speeches for Adlai Stevenson in the early 1950s and bestselling books throughout that decade--is no bad protagonist to follow through the tumult of mid-century America.

Even when Galbraith found himself far from the action--as ambassador to India, for instance, during the height of the Kennedy-Khrushchev staredown--Parker has an opportunity to shed some light into the era's obscurer corners. So we watch the Cuban missile crisis both from the Kennedy White House and from the vantage point of the Indian subcontinent, where Galbraith was forced to improvise an American diplomatic strategy to cope with the outbreak of the Sino-Indian War--a fascinating and almost-forgotten moment in Cold War history.

The book's intellectual narrative is less engaging, unfortunately, though this isn't entirely Parker's fault. Like any biographer of a talented writer, he's forced to offer brief and workmanlike summaries of famous books like The Affluent Society, which feel particularly plodding when contrasted with the often-sparkling excerpts of Galbraith's own prose that dot the biography's pages. And while Parker has taken as a subject one of the last economists who wrote for a general audience, a reader who lacks an abiding interest in economic theory is likely to find his eyes glazing over at times, amid detailed explanations of yet another slight Galbraithian revision of Keynesian theory.

That is, if he hasn't thrown the book away in annoyance, as some conservative readers will be tempted to do. Like many biographers, Parker is a partisan of his subject, and much of the book feels like a vindication, rather than a description, of Galbraith's work and arguments. In debate after debate, controversy after controversy, Parker insists or at least strongly implies that Galbraith was right and almost everyone else wrong. Sometimes this is persuasive (as in Galbraith's insistence that the Strategic Bombing Survey pointed to the limits of air power) and sometimes it is at least plausible (as in Galbraith's early proclamations of the folly of Vietnam). But even a sympathetic biographer ought to be willing to turn a skeptical eye on, say, Galbraith's early-1970s call for the U.S. to nationalize most of the country's largest corporations, after buying out their stockholders with government bonds.

Much of this partisanship could be forgiven, and perhaps even preferred to a tedious "on-one-hand, on-the-other-hand" attempt at perfect fairness. But Parker's account of Galbraith-as-hero creates a broader weakness in the book's narrative. Galbraith's career crested, intellectually and politically, with 1960s American liberalism, and then waned with it as well, so that the entire second half of the biography is a falling action, a decline into the political wilderness. Because the book is a vindication, not an elegy, Galbraith is inevitably cast as a Cassandra, prophesying to a deaf-eared country that inevitable doom will follow from the policies of an increasingly ascendant GOP. And because the book is a vindication, not an elegy, such predictions of doom are presented as almost invariably coming true.

So the failures of liberal, quasi-Galbraithian policies--the excesses of the Great Society, for instance, and the neo-conservative critique of the same--are passed over largely in silence. (Parker focuses instead on Galbraith's Johnson era anti-war activism.) And passed over, too, are many of the real economic achievements of the Reagan-Clinton-Bush decades. The Reagan boom is treated as a scandal-ridden blip in a decade of economic misery, and even the roaring Nineties are presented as a time when Americans were distracted by the Lewinsky affair from the reality of "global poverty, corporate crime, and income inequality."

This position can be defended, of course, but its defenders are primarily elements of the unreconstructed Left, who share Galbraith's shopworn socialisms, as well as his late-in-life conclusion that the Republican party has risen to power primarily by exploiting the innate selfishness of the typical middle-class American. Such partisans will find much encouragement in Parker's book, which has a hint of a call-to-arms about it. The epigraph, from Max Weber, informs readers that "we shall not succeed in banishing what besets us--the sense that we were born too late for a great political era--unless we understand how to become the forerunner of a greater one."

Heeding such an anachronistic trumpet would be a great mistake: Unhappy left-wingers casting about for a hero could do far better than John Kenneth Galbraith. But they could also do far worse, and conservatives frustrated by Parker's frequent lurches into leftist hagiography would do well to remember that there is also much to admire in Galbraith--the grace and dignity (sadly lacking in so many of today's bomb-throwers, Right and Left) with which he has carried himself as a public intellectual, but also the questions he raised about American life, and particularly about the purpose of our vast prosperity.

Having created the affluent society, Galbraith always asked, what kind of society do we wish it to be? Having embraced the free market, how can we make it serve an end greater than itself? One need not agree with his answers to feel grateful that he was willing to ask the questions--questions that in this age of conservative ascendancy are well worth asking again.

Mr. Douthat is an Atlantic reporter-researcher and the author of Privilege: Harvard and the Education of the Ruling Class, forthcoming from Hyperion Books.