John Wesley considered himself to be in the Reformation tradition of sola scriptura (Scripture alone), and he liked to refer to himself as homo unius libri (a man of one book).For example, see Preface, §5, “Sermons on Several Occasions,” Works (Bicentennial ed.), 1:105. For Wesley, Scripture represented the “words of the Spirit of God,” the “rule of faith” and “of right and wrong,” and the “inviolable Word of God.”“The Circumcision of the Heart” (1733, sermon 17), §2, Works (Bicentennial ed.), 1:402; “On Faith, Heb 11:6” (1788, sermon 106), I.8, Works (Bicentennial ed.), 3:496; “The Witness of Our Own Spirit” (1746, sermon 12), §6, Works (Bicentennial ed.), 1:302-3); and “Seek First the Kingdom” (1725, sermon 134), [§10], Works (Bicentennial ed.), 4:220). There was no question that Scripture represented the primary source of religious authority.
In affirming sola scriptura, Wesley never intended solus (alone) to mean exclusive religious authority.See also Albert C. Outler, ed., John Wesley (New York: Oxford University Press, 1980), 28, n101. Wesley considered Scripture primary, but he recognized that other factors played complementary roles in matters of faith and practice. In particular, Wesley referred to tradition, reason, and experience as inextricably bound up with Scripture in our understanding of true Christianity.
Some may question whether tradition, reason, and experience represent genuine sources of religious authority. But for Wesley, with his Anglican background, there was no question about including tradition and reason. To these he added experience as complementary to the primary authority of Scripture, particularly in confirming, illuminating, and applying the truths of Scripture. Wesley did not intend to be innovative; he intended only to make explicit that which had always occurred in theology. Yet his inclusion of experience represents a unique contribution to the development of theological method in church history.
According to Wesley, tradition represented the one source of religion other than Scripture that added substantively to Christianity. Scripture represents the primary substance of Christian belief and practice; tradition, reason, and experience represent complementary—albeit secondary—resources in the interpretation of Scripture. Yet tradition gives to us the canon of Scripture. It also gives to us the creeds and the earliest teachings of Christian antiquity, which provide the standards of orthodoxy.
With regard to reason, Wesley argued for the reasonableness of Christianity, for example, in An Earnest Appeal to Men of Reason and Religion. The idea of the reasonableness of Christianity was widely accepted in eighteenth-century Britain due in large part to the writings of John Locke. Wesley did not advocate a rationalistic or scholastic understanding of religion. On the contrary, reason represented an intellectual activity for reflecting upon the truths of Scripture, organizing those truths, and applying them.See Laurence W. Wood, “Wesley's Epistemology,” Wesleyan Theological Journal, 10.1 (1975): 52. See also “The Case of Reason Impartially Considered” (1781, sermon 70), §§1-6, II.10, Works (Bicentennial ed.), 2:587-89, 599-600. Certainly reason possessed limitations, but Wesley had no qualms about affirming the interdependent relationship between reason and a right interpretation of Scripture.
Wesley considered experience an essential factor in conceptualizing theology as well as in living out the Christian life. According to Wesley, experience does not supply the substance of Christian truth, but it serves to clarify and enhance that which Scripture teaches. He believed that Christianity involved more than “formal” or “rational religion”; it also involved the heartfelt witness of the Holy Spirit with our own spirits that we are children of God.See “The Witness of the Spirit, I” (1746, sermon 10), “The Witness of the Spirit, II” (1767, sermon 11), and “The Witness of Our Own Spirit” (1746, sermon 12) in Works (Bicentennial ed.), 1:267-313. This experiential dimension is crucial for personal faith as well as the establishment of individual beliefs. Experience, for example, may serve as a corrective to deficient interpretations of Scripture.See also Harald Lindström, Wesley and Sanctification (1980; reprint, Grand Rapids: Zondervan, 1983), 139. Like reason, experience as a source of religious authority has limitations. Wesley was well aware of how deceptive our experiences in life may be.See “The Nature of Enthusiasm” (1750, sermon 37), Works (Bicentennial ed.), 2:44-60. But he was convinced that there is an undeniable link between the truths of Scripture and our experience of them, and that the linkage should be recognized and developed theologically.
In summary, Wesley affirmed the primary authority of Scripture while at the same time affirming the genuine—albeit secondary—religious authority of tradition, reason, and experience. He saw the four sources of religious authority as complementary and interdependent. As a shorthand reference to Scripture, tradition, reason and experience, some Wesley scholars refer to the “Wesleyan quadrilateral.”Albert C. Outler coined the term “Wesleyan quadrilateral.” See “The Wesleyan Quadrilateral in John Wesley,” Wesleyan Theological Journal 20.1 (1985): 7-18. The term was not used by Wesley, and it should not be conceived as a geometric figure with equilateral sides and relations. Instead the quadrilateral should be conceived as a heuristic metaphor for studying the dynamic way in which Wesley understood the primacy of scriptural authority in concert with tradition, reason, and experience.