IN PURSUIT OF REASON The Life of Thomas Jefferson By Noble E. Cunningham Jr. Louisiana State University Press 432 pp. $24.95.

TO KNOW the full Thomas Jefferson, not merely the author of the Declaration of Independence and of a few famous maxims on human freedom, has been a formidable undertaking for even his most dedicated devotees. Since World War II, renewed interest in his life has resulted in a modern edition of his papers, massive biographies and countless monographs or polemical works. But there has been no concise, up-to-date biography for the general reader or for historians who specialize in other areas. Noble E. Cunningham Jr. has admirably met this need with In Pursuit of Reason, a volume in the Southern Biography Series.

Cunningham came to this task well prepared after writing two books and editing other volumes on politics of the Jeffersonian era. Such a background enables him to make clear in this biography what few Americans have seemed to understand: Jefferson was not primarily a philosopher of democracy but a practical man of affairs and a skilled politician, as well, of course, a child of the Enlightenment. Cunningham stresses this perspective in his preface: "Because Jefferson achieved his place in history as a public figure, not as a political philosopher, I have incorporated my account of his political thought into the narrative of his public career, rather than separating his philosophy from the context of the times in which he acted."

This outlook provides a balance to In Pursuit of Reason that admirers of Jefferson's ideas often miss. At every stage of his life he was most concerned with the application of his faith in reason and majority rule to practical measures for the improvement of society. Thus, to give only two examples, he spent much more time writing a proposed constitution for Virginia than in drafting the Declaration of Independence, and as president he mastered the art of party politics in order to push his program through Congress. Cunningham's brief biography makes a major contribution by encouraging its readers to see the administrator, diplomat, party leader, plantation owner, architect, educational reformer -- the whole Jefferson and not only the enlightened thinker whom 20th-century Americans have cast in the role of intellectual father of their democracy.

As so many recent writers have demonstrated, there is something in Jefferson for everybody. He was both liberal and conservative, democrat and elitist, localist and nationalist, politician and philosopher, agrarian and commercialist. No partial view does justice to this life that another Jeffersonian scholar, Merrill D. Peterson, has aptly characterized as exhibiting "seemingly bewildering conflicts and contradictions."

Despite such diversity, the author concludes and acknowledges in the title of this book that Jefferson's life was consistently motivated by his fundamental belief in the "sufficiency of human reason for the care of human affairs." "It was a faith," Cunningham writes, "that nourished his belief in progress, undergirded his political principles, explained his devotion to learning and to educational opportunity for every person, and produced the optimistic outlook that failed him only as he approached the end of a very long life."

Jefferson's belief in the sufficiency of reason as the source of human values developed in a society that he recognized to be, even in Virginia, increasingly evangelical. Nonetheless, his commitment to religious freedom won him the support of Baptists and other evangelicals who had suffered at the hands of the established churches in the South and New England. Those today who insist that society's values must be grounded on some particular religious creed would do well to read this timely volume, which helps to make clear the broad base of religious freedom in the new nation.

In Pursuit of Reason is likely to disappoint any one with more than a casual interest in Jefferson by omitting or slighting some favorite facet of his life. Yet, on balance, Cunningham's selectivity is fair and represents well the weight of recent scholarship that has given increasing attention to the president and party leader. Because of its brevity, this volume is a life without the times, an abridgment that leaves some questions unanswered. In one egregious example, the chapters on the American Revolution clearly describe his major contributions to that rebellion but provide little light on why he and his fellow Virginians revolted in the first place.

Reading this sprightly volume in the 1980s may leave one with a sense of de'ja vu. Its pages contain accounts of disputes over the national debt and foreign trade, of undercutting the secretary of state's direction of foreign affairs, of the seizing of hostages and resulting naval action against foreign terrorists, of leaks to the press and of a president weakened in the last years of his second term by his obsession with a single issue. Jefferson was convinced, as Cunningham notes, that it would be nearly impossible for a president to leave office with the same reputation as he had entered.

Perhaps the highest tribute that can be paid to this straightforward biography is that it may encourage readers to a fuller study of the Sage of Monticello in Dumas Malone's magnificent six volumes of Jefferson and His Time or of some of the less imposing works listed in the extensive bibliography of In Pursuit of Reason.

Charles W. Akers, professor of history at Oakland University, is the author of "Abigail Adams: An American Woman" and other books on the American Revolutionary period.