In his Disputation Against Scholastic Theology (1517), Martin Luther takes to task the “scholastics,” especially for their use of philosophy. The scholastics, as a collective reference, would have included two groups. The first of these would have been the followers of St. Thomas Aquinas, whose great synthesis of Christianity with the philosophies of Plato and Aristotle is known as “realism.” The second group includes the nominalists, who followed William of Ockham in rejecting realism and embracing a somewhat different view of how to account for the universal truths of reality.

It’s not necessary to go into the finer distinctions between these two groups, but Luther’s disputation rails against the type of theology that makes generous use of philosophical categories for organizing how theology is done. In one of his most strident theses, Luther writes that “Indeed, no one can become a theologian unless he becomes one without Aristotle” (LW 31:12). Aristotle stands in for an entire way of doing theology in the middle ages that made use of this ancient Greek philosopher’s system as an agenda for arranging and articulating Christian doctrine. Elsewhere, Luther provocatively refers to philosophy, or reason, as “the devil’s whore.”

Luther, of course, is no stranger to using philosophical strategies when it suits him. The Bondage of the Will (1525) deploys such arguments to lobby for the certainty of the gospel promise in relation to divine election. Likewise, some of his later disputations enlist some philosophical arguments about the new language of the Spirit (nova lingua) and its scriptural way of teaching the two natures of Christ.

Yet what Luther rejects is the use of philosophy as a program for theology. Philosophy is of great practical assistance in discerning truths about ordinary life and human experience, but it does not give Christians rules or an agenda for speaking of and for God. In this way, philosophy is linked with the law, since it reveals the deep structure of the world and explains its logic. Therefore, its use in theology is inherently limited and determined by the gospel, which speaks contrary to our common sense about the world. The gospel does not proclaim the results of our practical reasoning about things we experience, but the horror of God crucified for our sins and at our hands. The gospel operates outside of the strictures of both the law and human rationality.

Later Lutherans, especially after the Reformation, took a more positive approach to using philosophical categories and strategies in their theological writing. A prime example is the reintroduction of Aristotle’s notion of fourfold causality in many of the authors of later Lutheran orthodoxy. This incursion of philosophical thinking into the articulation of scriptural truth proves perilous at points, especially in the widening gap between justification and sanctification in some Lutheran theology after the Reformation.

The gospel operates outside of the strictures of both the law and human rationality.

When Aristotle’s philosophical system was largely discredited in the eighteenth-century with the advent of the Enlightenment, many Lutherans embraced the decline and adopted what came in its place, especially the philosophy of Immanuel Kant (1724–1804). Though Lutherans had inadvertently helped precipitate the Enlightenment by embracing Aristotle more optimistically than Luther, some Lutherans remained critical of the unhelpful accommodation to philosophy that was so common in the time after the Reformation.

Johann Georg Hamann (1730–1788) and Søren Kierkegaard (1813–1855) respectively embody the most notable Lutheran responses to the philosophical systems of both Kant and G.W.F. Hegel. Kierkegaard was especially critical of those Lutherans who adopted Hegel’s speculative idealism as the template for how they did theology. In this way, Hamann and Kierkegaard might be seen as carrying on Luther’s tradition of rejecting the use of alien philosophical notions in the task of articulating the living and proclaimed truths of God’s word.

So does philosophy have any role to play in contemporary intellectual conversation––amongst Christians and in theological reflection? Yes, it does. Some observations drawn from Lutheranism’s rocky history with philosophy will clarify why.

One is that philosophy and reason should be distinguished more carefully than they have been. Reason is an intellectual capacity God has given human beings––the creatures made in his image. Reason allows us to cultivate and utilize the wisdom we gather about the world to serve our neighbors and understand God's creation. Philosophy forms an indispensable part of the curriculum in a classic liberal arts education, especially at the college level. Reason is a gift of creation and should be celebrated as such. There will be those who are called by God into the vocation of learning and teaching philosophy. Their gifts deserve a home in higher education in the Christian tradition. But because reason is correlated with the law’s work in the world, its scope is naturally limited and established by the gospel.

A second observation is that reason might be a gift, but the history of philosophy is the old tale of this gift’s use by sinners. The traditions of philosophy as artifacts of human culture, longing, and theorizing are nothing less than the gospel’s religious alternatives stated in the most sophisticated forms. Philosophy should be read and understood––ancient, medieval, contemporary, and non-western––because it provides insight into what gospel proclamation might look like in an intellectual context. Theology is meant to drive towards proclamation to all people, and that includes even the brightest of minds.

Because reason is correlated with the law’s work in the world, its scope is naturally limited and established by the gospel.

Intellectual evangelism is augmented significantly if pastors and theologians take care to understand the various traditions of philosophical reflection. They will learn how to specifically apply the law and the gospel in alternative intellectual settings. Christian philosophers will be some of our greatest allies in this evangelistic task. This is the primary apologetic value of teaching and understanding the great philosophical traditions of western culture. For this reason, a retention of philosophy is a necessary aspect of higher education, especially in the Lutheran tradition. After all, it was Renaissance humanism (not to be confused with secular humanism) which bequeathed the reformers of many of their most valuable skills––especially the tools of debate and the ancient languages.

So in spite of Luther’s negative appraisal of philosophy, especially as a positive tool in theological reflection, Christians rightly teach and learn philosophy. Precisely, because wisdom is for life in God’s creation, it enables us to understand the world God has gifted to us more deeply. Yet at the same time, it’s essential for us to heed Luther’s warning to make our distinctions properly. Like the difference between law and gospel, theology and philosophy must be set in their proper places. When this is done, philosophy will teach us about a good life in the creation, and the gospel will predominate with its message of free forgiveness apart from the law and beyond the most sophisticated dreams of all human wisdom (1 Cor. 1:18).