There Is No Truce: A Life of Thomas Mott Osborne, by Rudolph W. Chamberlain. New York: The Macmillan Company. 420 pages. $3.50. Osborne seemed to have been born under fortunate stars. To the inheritance of family, culture and wealth he added personal attractions and accomplishments and power over men. And yet the stars turned malign. “Few men,” says his biographer, “have ever been so unerring in their choice of the losing side.” Mr. Chamberlain brings out the secret of his constant defeat. He was Don Quixote with a streak of the playboy.