The Varieties of Religious Experience: A Study in Human Nature is a book by Harvard University psychologist and philosopher William James.

As part of this development, the psychology of religion emerged as a new approach to studying religious experience, with the US being the major centre of research in this field.

This was a lecture series instituted by Adam Gifford and intended to have a popular and public audience on the subject of natural theology, or scientific approaches to the study of religion.

James considered healthy-mindedness to be America's main contribution to religion, which he saw running from the transcendentalists Ralph Waldo Emerson and Walt Whitman to Mary Baker Eddy's Christian Science.

James considered belief in the "mind cure" to be reasonable when compared to medicine as practiced at the beginning of the twentieth century.

[9] While James intended to approach the topic of religious experience from this pragmatist angle, Richard Rorty argues that he ultimately deviated from this methodology in the Varieties.

In his lectures on saintliness, the intention is to discover whether the saintly virtues are beneficial for human life: if they are, then, according to pragmatism, that supports their claim to truth.

Hence, Rorty argues that James ends up abandoning his own pragmatist philosophy due to his ultimate reliance of empirical evidence.

[18] James considers the possibility of "over-beliefs", beliefs which are not strictly justified by "reason valid universally" but which might understandably be held by educated people nonetheless.

[22] He says that individuals in the past had sought such universal proofs, asking "what more ideal refuge could there be than such a system would offer to spirits vexed by the muddiness and accidentality of the world of sensible things?".

[1]A July 1963 Time magazine review of an expanded edition published that year ends with quotes about the book from Peirce and Santayana:[24] He was simply impatient with his fellow academicians and their endless hairsplitting over matters that had no relation to life.

Its great weakness, retorted George Santayana, is its "tendency to disintegrate the idea of truth, to recommend belief without reason and to encourage superstition.

"In 1913 Josiah Royce wrote a paper on George Fox which he described as "a fragmentary contribution to that study of the "Varieties of Religious Experience" which William James has so significantly brought to the attention of students of human nature".

[28] The book was cherished by Ludwig Wittgenstein who wrote to Bertrand Russell that "Whenever I have time now I read James’ Varieties of Religious Exp[erience].