A prolegomena is simply an introductory essay or critical introduction to a book. From the word prolegomena (literally, “to say before”), we get the more popular word prologue. The purpose of a prologue in a book, or the prolegomena in a more formal, scholarly work, is to give information necessary to set the proper context for the work—information necessary for the reader to gain a proper understanding of what is going to be said in the body of the work.
In the study of systematic theology, prolegomena refers to the study of preliminary matters that are necessary to “set up” the formal theological study. These issues might include how the theological study will be conducted, how we acquire knowledge and arrive at truth, the theological system or tradition that will govern the study, and the sources that will be considered authoritative.
Prolegomena issues are important because they are often unspoken, but they powerfully govern the conclusions at which we arrive. For instance, if one person approaches theology as the study of God and what He has revealed, that person’s conclusions will be quite different from those of a person who approaches theology as simply the study of man’s stories about God. The goal of some theological works is to “prove” a particular viewpoint. Others simply assume a viewpoint to be true and explain theology from that perspective (Arminian theology, post-millennial theology, dispensational theology, feminist theology, or even gay theology). An evangelical apologist studying Mormon theology for the purpose of pointing out inconsistencies and points of tension between Mormon theology and Scripture will approach the subject very differently (and of course arrive at very different conclusions) from a Mormon apologist who is studying for the purpose of showing Mormonism to be simply another expression of orthodox Christianity. Similarly, a Mormon apologist who is attempting to make Mormon theology palatable to evangelicals would write a very different “Mormon theology” than would a Mormon author trying to explain it to fellow Mormons. These are prolegomena issues. It is important to know the viewpoint of the author, the purpose of the work, and the intended audience in order to fully understand the work. A Calvinist theologian writing to explain Calvinist theology to the average Presbyterian or Reformed church member can hardly be faulted by an Arminian for failing to adequately “prove” his viewpoint. From the standpoint of the prolegomena, both the author and the intended readers already shared a similar perspective.
Evangelical theologians take the Bible as the starting point and the final authority whereas liberal theologians might take human experience and reason to be as compelling as the Bible for determining truth. The current debate over “gay marriage” gives a good example. One theologian, taking the Bible as authoritative, would conclude that homosexual marriage can never be part of God’s plan. A different theologian, who gives equal authority to human experience and reason as to the Bible, may conclude that, since there are many homosexual couples who love each other and express devotion to God, then such unions must be acceptable to God. While it seems that the final conclusion is the real difference between the two theologians, it is actually the starting point that sets them apart and virtually guarantees different conclusions.
One of philosopher Immanuel Kant’s most well-known works is Prolegomena to Any Future Metaphysics That Will Be Able to Present Itself as Science. In this work, he tackles the issue of whether metaphysics is even possible. His conclusion was that we cannot really know anything outside of our experience of it. His presuppositions (his prolegomena) led him to his conclusion, as he had already rejected the idea that God could accurately reveal Himself to people so that they could actually know Him. Kant’s personal prolegomena pretty well guaranteed the conclusions of his written Prolegemona.
In any study or search for truth, the starting point is all-important, and any work that attempts to arrive at truth (even those that finally conclude that the only truth is that we cannot know truth) should be clear about the presuppositions that will govern the study. Christians would do well to examine their own presuppositions when approaching any issue. Likewise, it is often a fruitful exercise to examine any argument or proposition (whether theological, social, cultural, or political) to try to identify the presuppositions that have led to the position. This will help the Christian better understand how to interact with people who hold opposing viewpoints. Many viewpoints make sense if you accept the starting point. Therefore, the real area of argument is not the conclusion but the starting point—the prolegomena. A Christian who only argues against conclusions will probably be inefficient and ineffective in his apologetics.