Morris Raphael Cohen was an agnostic, despite the fact that he was introduced as a child to the traditional Judaic veneration for learning as well as a certain piety of spirit that remained with him throughout his life. His idea of scientific method emphasizes hypothesis, experiment, and systematic doubt. For no hypothesis is more than probable, though truth is our aim. Its principal expressions are theories that assemble apparently disparate facts by specifying their common character and relations. This conceptual cycle—hypothesize, experiment, then rethink organizing ideas if an hypothesis is falsified by the data—is also appropriate to legal and moral practice. For we don’t know what is best to do or not do, until experience has established the conditions for human well-being. This, Cohen’s pragmatism, abuts his realism and his moral sense. He never doubted that nature has an established form, one that we can know. Nor did Cohen doubt that well-being has conditions and characteristics that are universal, whatever the specificities of particular cultures. Some of them facilitate, others impede human improvement, though perfectibility is everywhere possible. Thought—critical, self-critical intellect—is the only reliable way to achieve it.

Dr. Cohen's collection contains essays written over the past twenty-eight years, but united by a pervading largeness of spirit, graciousness of style, and consistency of viewpoint. They reflect their author's profound devotion to the liberal temper, which he conceives not as a specific economic or political creed, but as "a faith in enlightenment, a faith in a process rather than in a set of doctrines, a faith instilled with pride in the achievements of the human mind, and yet colored with a deep humility before the vision of a world so much larger than our human hopes and thoughts."
The unique characteristic of liberalism, he believes, is its commitment to skepticism, to tolerance, to free inquiry, to the methods and principles of nationalism. "In the end, there is no way in which people can live together decently unless each individual or group realizes that the whole of truth and virtue is not exclusively in its possession." Nor is liberalism the product of any special economic or political circumstance. It is "older than modern capitalistic economics. It has its roots in the Hellenic spirit of free critical inquiry which laid the foundations of the sciences on which modern civilization rests."

Arthur M. Schlesinger, Jr. "Where Liberalism is Vulnerable," Commentary, 2, No. 3 (Sept. 1946), p. 250. This review of The Faith of a Liberal, Selected Essays by Morris R. Cohen summarizes Cohen's definition of liberalism in his own words.

Arthur M. Schlesinger, Jr. retired from the Albert Schweitzer Chair in the Humanities, City University Graduate Center, Department of History in 1996. He served as a special assistant to President John F. Kennedy and was a member of the Society of Fellows at Harvard University from 1939 to 1942.