Luther Seminary, Saint Paul, MN
1. Recent work on the dialogue between religion and science has raised the question again of what role knowledge from other disciplines (including the natural and social sciences) should play in the development and acceptance of theological truths. Against the attempt to seal-off the disciplines from one another, I have been developing a “mutuality model” for the relationship between science and theology. In this essay, which is preliminary and exploratory in nature, we will look specifically at the relationship between history (science) and christology (religion).  More specifically, our question is, what role should historical studies play in testing different theories of the incarnation? My thesis will be that historical science can and should influence theological positions adopted on the basis of revelation.
2. There are several possible ways in which the data of history can influence our christology, which can be understood as yet another example of the relationship between data and theories. There are at least three possible logical relationships between data and theories in theology (or any rational discipline). There is the relationship of proof (or disproof), which is the strongest possible. There is the relationship of coherence (that is, not incoherence), which is rather loose. Both of these are formal logical relationships, with established meanings in logic. In between these two formal relationships between data and theory are several weaker, informal relations. Two of these are abduction and retroduction. My purpose here is to explore these relationships, between the data derived from critical history (grounded in a theistic worldview) on the one hand, and Christian theology on the other, with particular reference to abduction and retroduction. So this paper is an exploration in theological method.
3. Our discussion draws upon the discipline of history, but does not take place within critical history. This is because, in my philosophy of science, historical studies deal with human explanatory schemes, not with explanation based upon God’s activities. Theological explanation is part of theology or philosophy, but not history itself. It is not part of historical studies, nor does it take place in biblical studies. It does, of course, draw upon conclusions and evidence from these other disciplines. I have insisted on a theistic worldview, however, simply because an atheistic historiography will finally undermine serious christology. The critical history we have in mind is one which takes place within broad Christian presuppositions about humanity, God, the world, and history.
4. The main point of the essay will be a simple one. Prior to any historical examination of the evidence, different christologies make plausible (i.e., expect) different historical evidence. This connection between theory and evidence is called “abduction,” also called the method of hypothesis. Retroduction goes under the name of “inference to the best explanation,” that is, an informal inference that the data make one theory rather than another more likely to be true.
5. One possible logical relationship between history and christology has already been fully explored by the Church, with the rise of historical biblical criticism. This is the logical relationship of coherence. The key question here is: do the implications of certain theological dogmas fit with the evidence about Jesus, as we know it from history? Theology has, for the most part, responded well to this question. The labours of Christian scholars in he field of New Testament studies in the last two centuries have demonstrated the coherence of full Christian faith and thought with outstanding Biblical scholarship. Critical Christian bible scholars have demonstrated that the careful historical study of Jesus, in a pluralistic and academic setting, is coherent with Christian doctrine. Now coherence has a clear, logical meaning: not incoherent. In other words, two propositions are coherent if they are not logically inconsistent. Demonstrating incoherence, however, is a difficult thing to manage, even on the best of days. Therefore, “lack of coherence” is a rather loose relationship between data and theory. In this brief essay, we will explore a closer possible relationship between historical studies and theological reflection. Because of lack of space, this exploration will be merely methodological – we cannot develop the crucial historical evidence in a mere essay.
6. The strongest possible logical relationship is proof (or disproof). Let us begin with a confession. I do not believe that we can, in fact, prove to a religiously pluralistic audience that an incarnation happened in the past. Even given the best historical evidence about Jesus that we have, and adding to it in any possible arguments from natural theology for the existence of God, the preponderance of evidence will not prove that an incarnation took place. If we are not already inclined to the Christian faith, the evidence is simply not staggering enough to overturn a reasonable but non-Christian worldview. We can demonstrate that Christianity is reasonable, but not that all other options are unreasonable. In other words, in an academic and critical dialogue with any and all types of religious scholars, the public and accepted evidence about Jesus (which is quite small) combined with whatever philosophical evidence we can give to argue that there may be a God: this total public evidence is not enough to convince a rational non-Christian thinker. The evidence about Jesus, not to mention the evidence brought forth in arguments for the existence of God, is either too slim or too controversial to do the job. I believe Tom Oden gets it right, when he notes, “[christology] is not a study that can be rightly undertaken by those who remain dogmatically committed to the assumption that nothing new can happen in history or that no events are knowable except those that can be validated under laboratory conditions. Christology is studied within the context of a worshiping community.” I therefore propose that we take his advice, and carry on the discussion of the relationship between historical science and incarnation within the academic field of Christian systematic theology. So we will now turn our full attention to theological “science.”
7. Even within the Christian tradition, we find many different theories of who Jesus was, that is, many different christologies. I intend here to discuss a traditional and orthodox notion of the incarnation. By incarnation in this essay, we will mean a “high christology,” that is, an event in which Jesus unites in his person both true humanity and full deity. Such issues involve a host of problems, and I am going to avoid any detailed logical defence of a high christology. We will not spell out a particular theory of incarnation, but will maintain a rather imprecise notion of Jesus as both God and human for our current purposes. In particular I am not going to decide between a two-mind christology and a kenotic christology. Instead, I intend to focus on a rather general “high” christology, and ask this question: what role does a critical historical examination play in our evaluation of a high christology? The logical relationship we will explore is abduction followed by retroduction. Both terms come from the philosophy of C. S. Peirce, and will be discussed more fully farther on.
8. This essay continues the work of my previous paper on the myth of a purely historical Jesus, as well an essay by William Alston (given at the same conference) on resurrection and biblical criticism. In particular, I take up my claim that “our spiritual knowledge of the real, risen Jesus must be subject to a critical, scientific reflection and historical examination” but not verification. The historical sciences cannot explain a miracle, although they can evaluate the reliability of the witnesses to any purported miracle. So the resurrection cannot be subject to historical verification. The term “verification” is used here in a technical sense, arising from philosophy of science. It means something like, “strong empirical demonstration” or perhaps even “proof.” The role of history in christology is not verification (in this limited sense) but rather historical examination and reflection. I was happy to see in Alston’s paper a similar viewpoint. He wrote, “She [the Christian biblical critic] is already working within certain views on the matter” of resurrection, and “she does not take historical research to be the sole determiner of what to believe.” In this way, “the historical results thus serve to shore up or weaken parts of the Christian belief system, without being allowed the presumption of completely determining even the historical parts thereof by themselves.” (Alston, 149f.) This is an important point, one that recapitulates the views of Reinhold Niebuhr and Herbert Butterfield among others.
9. The present essay will defend and explain this position on faith and history, with particular focus on the incarnation. We shall begin with three of the most important theologians of the past century: Karl Barth, Reinhold Niebuhr, and Wolfhart Pannenberg. Using C. S. Peirce’s notion of abduction and retroduction, I will then sketch an examination of the evidence for an incarnation that is based upon Christian faith, but gives historical reasons and arguments for this belief. In this way we seek to avoid both fideism and rationalism in theological method.
10. Giving up the forlorn hope for an empirical verification (i.e., proof from history) of christology, we move to a Christian systematic theology in which the primacy of Scripture and the centrality of Christ are already accepted. In this domain, the question of how we might know that an incarnation has taken place in history involves the notion of revelation. The theologian of revelation in our time, and arguably the most important theologian of the twentieth century, was Karl Barth. Barth’s christology sets the stage for the development of both Protestant and Catholic theology up to the present day.
11. Barth was a follower, in some ways, of a position that can be traced back to Martin K�hler (1835-1912) in his famous book, The So-called Historical Jesus and the Historic, Biblical Christ (1896). K�hler argued that the attempt to get behind the data to the “real” Jesus is simply not possible, and in a famous phrase he concluded, “the real Christ is the preached Christ” (K�hler, 66). Karl Barth likewise rejected natural theology, and any attempt to prove the Christian truth-claims in any area other than the revelation of God. In his early phase, Barth seemingly rejected the claims of historical criticism to give us the truth about the Bible. The Scriptures, he claimed in “The Strange New World of the Bible,” are not among us to impart historical knowledge but faith. “The Bible meets the lover of history with silences quite unparalleled.” When God acts, “something wholly different and new begins — a history with its own distinct grounds, possibilities, and hypotheses” (Barth, Word, 37).
12. Even in his more mature reflections, Barth insisted that faith needs no help whatsoever from history or any other source. “The dogmatic norm�can be no other than the revelation attested in Holy Scripture as God’s Word,” he wrote. “[E]ven faith’s presuppositions�belong to faith and cannot be recognized except by faith,” so that “faith is related to the whole of reality” but only by faith itself, not by science, history nor philosophy. Thus for Barth, “in view of God’s self-demonstration in His words and works no proofs on our account are needed.”
13. To be fair, Barth did use the historical critical method, and he argued that the Bible was also a human word, which must be read and studied historically (historisch) as a human word. But this historical study was not allowed by him to affect the truth of the revelation of God’s Word in the text of Scripture.
14. Barth has been criticized for an over-emphasis upon Christ and for what Dietrich Bonhoeffer called his “positivism of revelation.” I believe that a balanced and reasonably reply to Barth, one that is eminently British and follows in the tradition of Edwyn Hoskyns and Herbert Butterfield, has been given in recent times by Basil Mitchell. Mitchell argues convincingly that criticism, the reasoned examination of argument and evidence, is itself based upon some kind of trust or faith, which is part of every worldview. But at the same time, against Barth, Mitchell insists that faith also demands criticism. Faith in God as creator and redeemer in history, and as the ultimate reality and Truth, leads us in our reflective moments to wonder what public evidence we might give for our Christian faith, and for the gospel truths which come not from public evidence, but from special revelation. This is an argument one can find in other thinkers from other times, but Mitchell is one clear representative of this position. Of course there is no question here of proving the truth of the Gospel through history, science, or philosophy, nor do I seek to ground faith in rational argument. It is more a matter of what Steve Davis has called “soft apologetics,” that is, explaining the reasonableness of Christianity by starting with faith. This, after all, represents the famous position of Anselm, viz. fides quaerens intellectum. We may begin, with Barth, in faith and revelation. But at some point we will reflect critically upon our faith, and then we may seek evidence and arguments that, in Alston’s words, “shore up or weaken parts of the Christian belief system.”
15. One of Barth’s most severe critics was Wolfhart Pannenberg. Pannenberg argued that beginning “from above,” with the Christ of dogma, as Barth’s christology does, is not possible for “us” today. Pannenberg wanted to provide a christology “from below,” and to prove the resurrection from historical research. He was unhappy with any retreat into claims of faith and special revelation. He gave three reasons why a christology from above was unacceptable. Only the first one, however, is decisive:
A christology from above presupposes the divinity of Jesus. The most important task of christology is, however, precisely to present the reasons for the confession of Jesus’ divinity. Instead of presupposing it, we must first [!] inquire about how Jesus’ appearance in history led to the recognition of his divinity (Pannenberg, Jesus, 34).
One problem here is that Pannenberg failed in terms of pure historical science, and especially for non-Christian historians, to prove that Jesus rose from the dead. The “reasons for the confession of Jesus’s divinity” are to be found within the circle of faith, not outside of it. But the problem runs deep in his thought.
17. Pannenberg’s philosophy of history in this early period was problematic. In earlier essays leading up to his major work in christology, Pannenberg insisted that “the attempt to find a reality that is ‘suprahistorical’ depreciates real history.” In a well-known essay, “Redemptive Event and History,” Pannenberg insisted that faith must be found in history itself. Any attempt to provide “the suprahistorical ground of faith” is simply a refuge from “the scientific verification of events.” (Pannenberg, “Redemptive,” 16). Discussing a view similar to the one we are defending in this essay, Pannenberg argues that “a general collapse of historical method must result if there exists alongside it another, more fruitful way to certainty about past events, or if this other method were declared to be the right historical method.” Independent of Pannenberg’s own development over time, we should still ask the question, “Is this claim correct?”
18. In my own work in the philosophy of science, I have argued that historical explanation is based upon both hermeneutical understanding and causal explanations, drawn from the world of human beings, institutions, symbols, and structures. History as a scientific investigation explains events and explores meanings that human beings bring about. It does not and cannot explore what God brings about: that is contrary to the focus and methods of historical investigation. I cannot agree with Pannenberg when he writes “the question of the extent to which the historian as such may make any sort of statement about God can remain open for the time being.”(Pannenberg, “Redemptive,” 66). Showing more of his true colours, he later suggests that “the concept of God” should be “really indispensable for the historian.”(76). This is a misunderstanding of the goal and methods of historical science. Critical history as such does not deal with God. It may indeed deal with human beings and their beliefs about God, or with reports of religious and other experiences, but the explanatory focus of historical science is upon human agency and institutions. For example, if I wanted to date an eclipse in the distant past, I would not consult an historian. For this knowledge, we need astronomy not history. Just because something is a past event, it does not follow that historical science can verify or explain it. History examines the human past. I am not arguing that history (i.e. the past) is “closed” to divine agency. The point is about the explanatory focus and limits of historical explanation and verification. Critical history, understood as science, does not deal with God because its methods and focus look to the human world.
19. The position I have adopted should not be confused with “methodological naturalism.” I reject this way of describing scientific practise. The very terminology is objectionable. There just is no such thing as merely methodological naturalism. Arguments both for and against this position usually end up being an attack on, or defence of, full-blown naturalism. The terms “methodological naturalism” are a front for full-blown naturalism, in a way that is sometimes subtle (as with A. C. Danto) and sometimes not so subtle (as with Phil Johnson).  My own position has nothing to do with naturalism of any kind. Instead, the issues are more complex. A brief sketch of my philosophy of science is all we have space for here.
A. Scientific research is conducted within a “paradigm” or research programme, which includes background criteria, values, methods, theories and knowledge.
B. Our worldviews (Weltanschauung) influence any and all scientific research and argument. They provide the ultimate foundations for scientific research programmes.
C. When a Christian worldview provides presuppositions, values and the interpretive horizon for the arts and sciences, this results in Christian scholarship. The major alternative to a Christian worldview in our place and time is scientific materialism (or naturalism).
D. The aim of a science determines the methods, explanatory focus and interests of that particular discipline.
E. Academic disciplines are traditional practises. Researchers are inducted into them, including their background research programmes.
F. Each academic discipline has its own explanatory focus and research tradition which circumscribes the specific aspect of reality it is competent to judge.
20. While all the sciences aim after the truth (as Steve Evans has insisted), we must also pay attention to the particular areas of reality that specific sciences aim at. History has as its focus human institutions, events, and symbols. While there is no such thing as a fixed historical method, there are enough similarities among the best current historians to speak of a contemporary critical historical methodology. This methodology is, of course, open to change. My only claim would be that it is the best set of practises we now have, given the aims and purposes of historiography (that is, to examine the human past in terms of human and social explanations and interpretations). A full explanation of the past will always require more than history itself can provide. A full explanation will always be inter-disciplinary because there is more to reality than any one discipline studies. For this reason, as David Brown insisted, when historians write their popular books, they always go beyond critical history in the interpretation of the meaning of their results. This is because history (like all disciplines) raises questions that it cannot answer.
21. The postulation of things that are “suprahistorical,” then, does not denigrate history. Critical history is unconcerned with the suprahistorical. The laws of nature, for example, make historical events possible in the first place. They are not part of history; yet apply throughout “history,” that is, throughout time and space. While historical events depend upon such laws, history cannot explain the truth of scientific laws. Pannenberg seems to expand “history” to encompass all of reality — a major philosophical problem in his early thought.
22. Ten years before Pannenberg published his first papers on history and revelation, a more moderate and reasonable position on faith and history was developed by Reinhold Niebuhr. Niebuhr’s book Faith and History was part of a spate of books on Christian faith and history, sparked by dialectical theology, especially the works of Karl Barth. His volume anticipated many of the themes Pannenberg took up some years later. Already in 1949 Niebuhr was discussing “Universal History,” for example. In my view he developed an understanding of revelation and history that is an advance upon both Barth and Pannenberg.
23. Like Barth, Niebuhr begins the Christian understanding of history with faith. “The truth of the Christian faith must, in fact, be apprehended in any age by repentance and faith. It is, therefore, not made acceptable by rational validation in the first instance.”(Niebuhr, v.) I would call your attention to the words “in the first instance,” for after repentance and belief in Christ, some rational exploration and defence of a Christian understanding of universal history are possible. But first we must begin with faith. “In Biblical thought,” he argued, “the grace of God completes the structure of meaning beyond the limits of rational intelligibility in the realm of history” (115). Why is faith and repentance necessary? Because of the “idolatrous tendencies in all human culture,” repentance is necessary for a grasp of gospel truth (116). “Such faith must be grounded in repentance; for it presupposes a contrite recognition of the elements of pretension and false completion in all forms of human virtue, knowledge, and achievement” (171). No French thinker could put it better! But faith is equally needed. “The radical otherness of God is an offence to all rationalistic interpreters of life and history. Yet the worship of this God is the basis for the first genuine conception of a universal history” (116). Niebuhr goes on to make an excellent point, against Pannenberg’s position, that “mystery does not annul meaning, but enriches it. It prevents the realm of meaning from being reduced too simply to rational intelligibility and thereby being given a false centre of meaning in a relative or contingent historical force or end” (116).. Theological truths must not be reduced to historical facts, however much they may be about the events that really happened in the past. Contrary to the fears of Pannenberg, Niebuhr does not retreat into subjectivism. Instead he goes on to argue, at length, for the superiority of a Christian understanding of history and its meaning. In fact there is even a chapter on “The Validation of the Christian View of Life and History.”
24. From Reinhold Niebuhr, then, we have learned a sound and reasonable view of the relationship between faith and reason, revelation and history. Niebuhr, of course, was influenced by Karl Barth, but did not fall into the latter’s over-emphasis on revelation and faith. Unlike Pannenberg, Niebuhr realized that “mystery does not annul meaning, but enriches it.” The dimension of faith and the “suprahistorical” does not destroy history, but fulfils it.
II. Reasoning about an incarnation.
25. With the specific example of the incarnation, then, how would such a position of “faith seeking understanding” work in actual practice? The mainstream of Christian faith and tradition has delivered to us the idea of a real incarnation. The real Jesus of history was and is (according to catholic, orthodox faith) both fully divine and fully human. A number of criticisms have been levelled against this idea in the last two millennia, making this orthodox belief problematic for our place and time. I believe that Christian scholars have already replied to the challenge of coherence between historical research (historical-critical methods) and theology, as remarked earlier. Despite their careful work, we still need to clarify some misunderstandings that critics have passed on to modern women and men, before we can consider this idea and develop an historical examination of it. We can then consider C. S. Peirce’s method of abduction, and the implications of that logic for an historical exploration of the incarnation hypothesis. This approach using “abduction” assumes that the issue of coherence has already been settled. But as we noted earlier, “coherence” logically turns into “lack of incoherence” – and this is a very loose relationship, since incoherence is so hard to prove.
26. We will treat an historical incarnation as a hypothesis, but one within the circle of Christian theological reflection and not outside it. There is no question here of seeking on the basis of historical evidence to demonstrate the truth of the Christian religion to the sceptic. Both Lessing and Hume, in the eighteenth century, rightly rejected this as an implausible programme. But even the task of treating a matter of doctrine as a hypothesis raises a serious problem for some theologians and philosophers of religion. They would argue that rational criticism of the faith treats the deliberations of faith in a hypothetical way, and is thus contrary to faith. This viewpoint can be traced back through dialectical theology, to Søren Kierkegaard. Even though I am a great fan of SK, on this point he overstates the case. There are different moments and models in the life of faith itself. Critical reflection upon the fact that we find ourselves believing in something (or Someone) is a normal part of the life of faith, once we enter upon it. Mitchell has argued this well, as we have already noted. Along the same line, Sir Edwyn Hoskyns in 1931 rightly noted that “in consequence [of the incarnation] the Christian religion is not merely open to historical investigation, but demands it, and its piety depends on it.” There are ups and downs in our spiritual journey, moments of strong existential trust and moments of thoughtful reflection, times for rational argument and times for emotional worship: these facts are confirmed in the lives of many believers. Kierkegaard’s pseudonym (Johannes Climacus) speaks of only one moment in the life of faith. There is another moment, that of faith seeking understanding, which demands critical and rational evaluation of our faith.
27. Similarly, we must defend the idea of a logical exploration of faith against certain tendencies among some followers of Wittgenstein. The problem here would be put in terms of the “grammar” of faith. If we treat the incarnation in a factual way, as a hypothesis, this treatment is contrary to the “meaning” of religious language, which is grounded in a way of life. As Wittgenstein once remarked, “In religious discourse we use such expressions as: ‘I believe that so and so will happen,’ and use them differently to the way in which we use them in science.” Belief in the incarnation, so the complaint goes, is a “grammatical remark” about living in, and making sense of, a deeply Christian way of life. It is not (for them) a factual statement, but part of a form of life, a Christian way of being in the world, which makes sense only as part of that whole picture. Wittgenstein objected to Christian philosophers who attempt to demonstrate the reasonableness of Christian faith. He remarked: “Not only is it [Christian faith] not reasonable, but it doesn’t pretend to be. What seems to me ludicrous about O’Hara [a Catholic philosopher] is his making it appear to be reasonable.”
28. Teasing out the meaning of Wittgenstein’s cryptic remarks concerning religion would take us too far afield, and his views can be interpreted in more than one way. While he rightly points to religious practice and life as the space within which religious language makes sense, he seems to me (if I understand him correctly) to omit the idea that faith itself might demand some kind of critical examination, which would include factual issues drawn from other areas, perhaps even from the sciences. This is the position of Augustine and Anselm, in the tradition of fides quaerens intellectum. We are in good company, then, when we insist not only that the meaning of religious language is found within religion but also the truth of religious language may include issues and criteria outside the “language-game” of religion. My final point would be that even these “external” criteria and evidence are not “neutral” relative to faith. We can and should approach them, too, within the presupposition of a Christian worldview. Yet just as clearly, some evidence is public and pluralistic, available to any reasonable person who shares the common values and assumptions of a scientific worldview. What I am recommending, then, is a worldview that is both scientific and Christian.
29. Once we allow that standards of what counts as good evidence, good argument, coherent and clear meaning, can come to religious beliefs from outside religious language and practise (but not necessarily outside a Christian worldview), another problem with a real incarnation immediately arises. Philosophers have sometimes complained that the very idea of a real incarnation is logically incoherent. John Hick is famous for making just such a claim. I believe this complaint has been decisively refuted by a number of philosophers in recent literature. We cannot consider all such issues in this essay, but need to press forward to historical (rather than logical) considerations.
30. The last point, however, does call for some development of our hypothesis. To avoid confusion, we should spell out what we mean by an historical incarnation. At the very least, this implies that Jesus was a real human being and lived a true human life. At the same time, the person that was Jesus was identical in some way (however we define it) with God the Son. God the Son, in this case, is one member of the Blessed Trinity. Any orthodox exposition of the incarnation depends upon the doctrine of the Trinity. With this in mind, I would argue that the orthodox, catholic view of an incarnation is committed to the reality of personal identity, but not to any one theory of what personal identity is.
31. Another point of clarification has to do with what we can expect, historically, from the “consciousness” of an incarnate human being. From the fact that, ex hypothesi, Jesus shares the divine nature of God the Father, it does not follow that Jesus always knew he was in some way identical with God the Son. It is logically possible to have a property without being conscious of that property. For example, I may have the power to fly by flapping my ears. But since I am ignorant of that property, I will never use that power. To use a somewhat less arbitrary example, a baby boy raised by wolves may have the property of being human without knowing that he is human. So there is no reason to presume that, on the hypothesis of a real incarnation, Jesus will know he shared the divine nature with God the Father. In other words, if Jesus is truly human as well as divine, there is no reason to presume that Jesus was conscious of his divinity.
32. One could spend an entire volume just clarifying the misunderstandings of orthodox christology. I hope enough has been said here to at least indicate the character of the hypothesis under consideration, so that a different kind of reasoning can take place.
33. Let us return to the central question of this essay: what role does evidence from historical research play in deciding for or against a real incarnation? I have rejected the logical relationship of proof, as too strong for the evidence we have from history and philosophy. We cannot prove that the incarnation took place, by public evidence and scientific reasoning, for a pluralistic body of learned scholars. We have noted the logical relationship of coherence, but put that to one side also, as having been already explored fully. Looking at another type of logical relationship between historical evidence and theological theory, I would argue that historical considerations can help us, within the Christian faith and thought, to prefer some christological theories to others. Of course such considerations take place within Christian theology. They are neither history, nor are they simply biblical studies. But in “dogmatics” and doctrine itself, I propose to use the method C. S. Peirce called “abduction”: that is reasoning from a hypothesis to the measurable results that would obtain if it were true. This form of scientific, informal reasoning takes place within a set of rival hypotheses and within a particular discipline. Next, given our background knowledge, we look for further evidence which (if found) would render one hypothesis, rather than the other, more probable. If we take a criminal investigation, for example, we might look for evidence (say, a good alibi; or blood stains on their clothes) which would render one person, rather than some other suspects, more likely to be guilty. This kind of reasoning about probable explanations and hypotheses is common in many human endeavours. This second task goes under the name of inference to the best explanation (Peirce called it retroduction). Abduction, then, moves from a theory to the (hypothetical) evidence; while retroduction moves from the evidence to a theory which best explains that evidence.
34. The discipline in question here is Christian systematic theology. We are not talking about all worldviews and religions, but a set of ideas about Jesus within the presuppositions of Christian faith, life, and tradition. To avoid begging the question, however, we must not presuppose any one christology. Which christology is, given all our evidence from history, philosophy and theology, most likely to be true? Granted that we believe in some kind of revelation in Christ and scripture, how shall we best understand and apply that revelation, given our total evidence? As just such a juncture, issues of reason, argument, evidence, and science come into play, as we seek a coherent and reasonable Christian theology and worldview.
35. There are a number of systematic theories about the person of Christ. For issues of simplification and illustration (since this essay is merely an example of using historical research in theology) we will speak broadly of three hypotheses. The first is the orthodox viewpoint we have been discussing so far, that is, a real incarnation. The second broad theory is that Jesus was a great moral and religious leader whose life is an important example for all people. This theory we could call Ebionite. The third broad theory would be Arian. On this hypothesis, Jesus was a real human being who shared the nature of some divine being or other, but not the one true God who is Creator and Lord of the Universe. If we apply that method of scientific thinking which Peirce called abduction to these three theories, what is the result?
36. The area of research we are interested in is historical science. Therefore, when we are looking for measurable results of each theory, the “measurement” in question is one limited to critical historical research. Let us be clear: every element of reason and evidence, from any and all disciplines, is not under consideration here. Rather, we limit ourselves to what we can expect historical study to reveal. Historical science, in turn, is based upon research into the human: human actions, human symbols, and the meaning and significance of events for humans and from their perspective. Albert Outler once gave a fine, brief definition of the nature of critical history: “The historian’s chief business, we might perhaps agree, is the re-collection and re-presentation of selected segments of the human past, in an intelligible narration based on public data verified by scientific observation.” It is in this field, then, that we will seek “measurable” differences between the three hypotheses, assuming each to be true.
37. With respect to Arian christology, I would recall the earlier conclusion that Jesus may not have in fact been conscious of his deity. Under this assumption, I can think of no historical evidence which we might plausibly expect to find, that can distinguish between Arian and Orthodox christologies. After a good deal of reflection, I have simply reached a dead-end on this topic. What measurable results (in terms of historical research) might come from one, rather than the other, being true? Given my assumptions about the consciousness of Jesus, I could find none. I suggest we simply leave Arian christology to one side, at least for the present.
38. Let us examine, then, the two major options we are left with: an orthodox incarnation or an Ebionite (or Liberal Protestant) christology. What measurable, historical results can distinguish between these theories? In both cases we can expect profound moral and religious teachings that draw us closer to God and to one another. In both cases, we expect that Jesus would have a profound effect upon his followers. In both cases, we expect that he would demonstrate a powerful spiritual life, and closeness to God. However, if we assume the truth of an incarnation, we have more expectations than if Jesus were merely a great teacher, prophet and moral example. This would be true even if Jesus, while on earth, was not fully conscious of his deity.
39. If Jesus is in some way identical with God the Son, we would expect that he would have a mission on earth that was of supreme importance. Otherwise, why would God bother with an incarnation? This argument is based upon background knowledge about God that Christians in general share over the centuries. The kind of God that creates the Universe and saves Israel would not undertake an incarnation without a profound purpose behind it. This first point is compatible with an Ebionite christology, however. Secondly, given our background information about God, surely She would ensure that this human life would have outstanding positive historical impact. God has good reasons to want the effects of this incarnation to be widely known, even if there are good reasons to allow human beings to be the means of spreading the gospel. Thirdly, we might also expect that the Incarnate One would display some supernatural powers, perhaps over the natural world, or over the forces of evil and darkness, or perhaps even over death. This is quite distinct from what we would expect from a great moral example and teacher. Again, the issues here are not empirical. We are not asking if, in fact, some great moral teachers have performed miracles. We are asking what, given our general knowledge, we have a right to expect from each hypothesis (if it is true). Some great moral teachers or prophets may have power over death, for example, but we should not expect that one will, based only on the fact that she or he is a great moral teacher or prophet. Finally, given a real incarnation, we would expect a very early worship of that Person, even among monotheistic disciples. On an Ebionite christology, such worship would be blasphemy for a monotheist. So there are expectations of an actual incarnation, which go beyond our expectations of an Ebionite christology.
40. Perhaps we should make the point again, that if Jesus lived a real human life, he might not know that he was in fact personally identical with God the Son. We would expect him to have a unique and always intimate relationship with God the Father and God the Holy Spirit: but that could equally well be true of the other two hypotheses as well. So the area of Jesus’ so-called “divine self-consciousness” is shown to be irrelevant, once a proper grasp of the relationship between critical history and christology is laid out. Logically, any consciousness of divinity we expect of Jesus is based upon the unexamined assumption that a real incarnation logically entails a divine self-consciousness: and this is false. So this area of expectation provides no distinguishing characteristics, at least for historical evidence, between our three christologies.
41. Given these sorts of expectations, then, we must now turn to historical science. From this list of expectations, what can we expect critical history to actually measure? What recoverable results could historical research possibly uncover, which might correlate with our list of expectations (assuming the truth of an orthodox incarnation)? The best kinds of historical evidence are eye-witness reports, and conclusive archaeological remains and traces. Let us take our three historical expectations, listed in the above paragraph, and consider the kind of measurable evidence that (in principle) historical science could unearth. A full and complete exploration of this question would need to demonstrate (more fully that we can do so) why these expectations – and not others – are being considered. I can only report here the results of that reflection, and have no space to explicate and explain it.
42. First, special or “supernatural” events could be witnessed by various people, who reliably recorded their observations. This is the best kind of evidence we can imagine finding for supernatural events, as both Lessing and Hume recognized. It is difficult to imagine any archaeological evidence that might be recovered in this regard, although that might be possible in theory. As previously remarked, historical science cannot determine whether miracles are or are not possible. Critical history can provide good evidence for doubting that some supposed event really happened (for example, all stories about this event are recorded centuries after it supposedly took place); but on the positive side we can at best expect good evidence that some persons, with reliable character, witnessed supposed “miracles.” Second, the strength of historical impact is something that can be measured and weighed by historical research. How important and valuable was this life, compared to other human lives, with respect to the influence it played upon the rest of human history? While it would be quite difficult to prove that any one person had the most positive historical impact, one can imagine building a good case that some individual had a really profound positive impact upon history: as good as any other individual we know. Third, with respect to the importance of his mission, historical research can recover, at best; that the Incarnate One and his or her followers believed that mission was of worldwide spiritual significance. Whether it actually was of such import, history cannot decide, given its limitations and methods. Critical history can also discover whether this life did indeed have a worldwide religious impact, but that falls under number two (above) and is not a separate piece of evidence. And finally, there can be reliable evidence that early followers of the Incarnate One worshipped him, even if they were monotheists.
43. Using the logical connections between theology and history that I am urging (abduction, retroduction), we have discovered that evidence from history does play some role in decisions within systematic theology about theological truths. However, this role is a modest one. Historical evidence alone cannot decide which of our theological hypotheses is true. But critical history can help us make that decision, in the context of a much larger and longer argument. As we might expect, theological hypotheses are based very much on theological reasons and evidence, rather than the evidence of historical science. Nevertheless within its limited and modest role, history does have something to say. I was myself rather surprised to see the quite limited role critical history plays in arguments about christology. But the point remains, against Barth and Wittgenstein, that scientific results outside religious language and special revelation do have an epistemological impact upon decisions concerning theological truth.
44. We should notice that we are dealing with a cumulative case argument here. Having applied abduction to the various hypotheses, we are now looking at the overall evidence for a best explanation (retroduction). And in this case, what counts as a best explanation will be a cumulative case argument. No one piece of evidence is decisive. We must consider the weight of them all together. Some pieces of evidence are compatible with an Ebionite christology. But the major logical point will be about what we have a right to expect, given an Ebionite christology. Jesus being a “miracle worker” is compatible with an Ebionite christology, but it is simply an ad hoc addition to the Ebionite hypothesis. Given the Ebionite hypothesis, there are no grounds to expect, prior to historical considerations, that the great Guru or Prophet would also be a miracle worker.
45. I believe that a good, solid historical argument can be made for the four areas of evidence we have come to expect, through abduction, if there really was an incarnation. This will mean that, though retroduction, a real incarnation is more likely to be true. I will not attempt such a demonstration at this time. But I will simply state that one could show, historically, that Jesus had a tremendous positive impact upon world culture and history after him. One could show, historically, that Jesus and his followers believed his mission was of worldwide spiritual significance. Third, one could show historically that early, diverse, and otherwise reliable traditions concerning Jesus report that he had supernatural power over nature, over demonic forces, and even over death. Finally, one could show on good historical grounds that the early monotheistic followers of Jesus did indeed worship him. As we noted earlier and often, historical science cannot prove that such miracles occurred, but only show that there are reasonable witnesses to these events. But even these limited results are illuminating. I am fascinated by the fact that, once we clarify the proper relationship between critical history and theology, historical science seems to favour (at least prima facie) an orthodox incarnation over an Ebionite theory.
46. The concern in this essay has been methodological. Notice how very far the logic of this position is from the debates of the modern period exemplified by Locke, Hume, or Lessing. There is no question of historical science demonstrating the truth of the Christian religion. Rather, a proper grasp of theological method insists that we begin with faith in Christ, and accept the broad traditions within the Christian theology. Our argument begins within the circle of faith. But notice, too, that historical science can and does affect our systematic theology. In particular, the historical evidence would seem to favour an orthodox incarnation over an Ebionite christology. But historical evidence of this modest sort is not decisive. The larger and longer argument about christology must take place within the total evidence available to the systematic theologian.
47. I suspect that some readers of this paper may feel disappointed. All along, in this essay, we have assumed the Christian faith. We must start from faith, I have been arguing. Is it so surprising, then, that we arrive at results compatible with Christian faith when we look at history? Aren’t we just arguing in a circle? My answer to these doubters is twofold. First of all, people do not as a rule come to their basic faith-stance (whatever worldview they may hold) because of reasons, evidence, and argument. People accept the Christian faith (for example) for existential, emotional, spiritual, and fundamentally religious reasons. Second, I do think that public evidence and argument can be given for the Christian worldview, in the context of the large set of rival worldviews in our culture today. Some of this evidence will be historical, and some will be philosophical. Historical evidence is of limited but real value in the rational, open, and pluralistic debate between rival worldviews and traditions. While I assume the truth of the Christian religion in this paper, I am willing to argue for it in other contexts. So my complete position is not circular. Third, the fact that we begin with faith has not, in this particular case, led to a circular argument. We begin with Christian faith, but also with a plurality of christologies. So we have not assumed the truth of the incarnation. Thus our argument (which is actually about which christology is true and not about the whole of Christian faith) is not a circular one.
48. Finally, in the minds of some, there may be a lingering doubt about the “tensions” between theology and historical science. Have we not heard, many times over, that the presuppositions of scientific history and of theological reflection are in conflict? Can the theologian also act as a critical historian? What about Lessing’s “ugly ditch” between religion and history? My own view of the matter is this: the problem dissolves when we give up the Enlightenment pretensions of rationalism and “neutral” scientific research, and when we pay attention to the methodological limits of both theology and science. Since I have already argued this point at length elsewhere, there is little need to rehearse it again in this place.
49. What have we learned, then, from this methodological exercise? I have argued that we can and should avoid the twin errors of rationalism and fideism. In particular, we discovered through various logical relationships (proof, coherence, abduction, and retroduction) the real but limited role that historical scientific results can play in theological reflection. I was myself astounded, in completing this exercise, to find that the cumulative weight of historical evidence (upon a proper conception of the relationship between theology and history) is prima facie in favour of a real incarnation, when compared with an Ebionite hypothesis. A sound historical case can be made that Jesus of Nazareth had as great and good an impact upon world history as any other ancient individual. A very good case can be made that, in all the earliest traditions about Jesus, we find he was a wonder-worker with “supernatural” powers of some sort. We can likewise discover, through sound historical scholarship, that both Jesus and his followers understood his mission to be of worldwide spiritual significance. Finally, there is excellent historical evidence that the early followers of Jesus worshipped him, even though they were monotheists. Thus, astonishingly, the sum of historical probability is in favour of an orthodox christology, understood as one hypothesis among others within Christian theology. We must remember that christology is not a scientific discipline, but a theological one. Historical evidence is only part of the picture. Remember, for example, that our historical data cannot decide between an orthodox and an Arian christology. Still, the methodological point remains: historical science shapes theological truth-claims. Can thoughtful Christians any longer maintain the nice, clean distinction between the Jesus of history and the Christ of faith?
 See A. G. Padgett, “The Mutuality of Theology and Science,” Christian Scholar’s Review 26 (1996), 12-35, and my Science and the Study of God (Grand Rapids: Eerdmans, 2003).
. I will use the word “scientific” in a very broad sense, to refer to critical, academic historiography. We should resist the temptation to reduce science to physical science, which after all is only one branch of the special sciences.
. T. C. Oden, The Word of Life: Systematic Theology, vol. 2 (San Francisco: Harper, 1989), 7. I believe William Lane Craig is too optimistic when he insists that the historical facts about Jesus will lead any careful scholar to affirm his divinity. See his book, Apologetics: An Introduction (Chicago: Moody Press, 1984), later published as Reasonable Faith (Wheaton, Ill.: Crossway Books, 1994), 243-51.
. See W. Alston, “Biblical Criticism and the Resurrection,” in S. Davis, D. Kendall, and G. O’Collins, eds. The Resurrection (Oxford: Oxford University Press, 1997), 148-83; and A. Padgett, “Advice for Religious Historians: On the Myth of a Purely Historical Jesus,” in the same volume, 287-307.
 Padgett, “Advice,” 292n.
. H. Butterfield, Christianity and History (London: G. Bell, 1949). I will discuss Niebuhr more fully below.
. Translation by Carl Braaten (Philadelphia: Fortress, 1964). Braaten has a fine introduction to K�hler, and to the book’s importance.
. Karl Barth, The Word of God and the Word of Man, trans. D. Horton (Boston: Pilgrim Press, 1928), 36.
. Karl Barth, Church Dogmatics, trans. and ed. by G. W. Bromiley and T. F. Torrance, 4 vols. in 13 parts (Edinburgh: T. & T. Clark, 1936-1969), I/2, 815 (hereafter cited as CD).
. CD III/1, 63.
. CD III/2, 79.
. CD I/2, 464. See this entire Chapter III (pp. 457-741): Holy Scripture.
. D. Bonhoeffer, Letters and Papers from Prison, trans. R. H., Fuller (New York: Macmillan, 1970), 168. See also, among many sources, Hendrikus Berkhof, Two Hundred Years of Theology, trans. J. Vriend (Grand Rapids, Mich.: Eerdmans, 1989), 208-28, on the theological responses to Barth.
. B. Mitchell, Faith and Criticism (Oxford: Oxford University Press, 1994).
. The error of G. E. Lessing, in his 1777 tract On the Proof of the Spirit and of Power (which created his famous “ugly ditch” between religion and history) was to assimilate religious truths to the “necessary truths of reason.” On the contrary, religious truths are almost never logically necessary propositions. Even if “God exists” is logically necessary (as some who accept the ontological argument believe), ontological arguments for this proposition are not historical but philosophical and logical. All other religious truths are logically contingent. See H. Chadwick, ed., Lessing’s Theological Writings (Stanford: Stanford University Press, 1956), 53.
. See S. T. Davis, Risen Indeed (Grand Rapids, Mich.: Eerdmans, 1993). A similar position is advanced by William Placher in a deeply philosophical volume from a theologian: Unapologetic Theology (Philadelphia: Westminster Press, 1989).
. W. Pannenberg, Jesus — God and Man (London: SCM, 1968), 33-7.
. W. Pannenberg, “Redemptive Event and History,” reprinted in his Basic Questions in Theology, vol. 1, trans. G. Kehm (Philadelphia: Westminster Press, 1983), 15-16.
. “Redemptive,” 38. Pannenberg is discussing Erwin Reisner, Offenbarungsglaube und historische Wissenschaft (Berlin: Haus and Schule, 1947). This is a short pamphlet on the topic.
.See my chapter on the myth of a purely historical Jesus in The Resurrection, 287-307, and my essay “The Mutuality of Theology and Science,” Christian Scholar’s Review 26 (1996), 12-35, both cited above.
. This would be true even if the evidence for the existence of God were much greater than it is. My remark is based upon the aims, research methods and paradigms of historical science, which does not concern itself with the truth about God. Historical science is about human beings (which includes the history of religions, but not theology proper). I thank Steve Davis for this question.
 See, for example, A. C. Danto, “Naturalism,” in P. Edwards (ed.), The Encyclopedia of Philosophy (New York: Free Press, 1967), 5:448-450; Phillip Johnson, Reason in the Balance: The Case Against Naturalism (Downers Grove: Intervarsity Press, 1995); or Willem B. Drees, Religion, Science and Naturalism (Cambridge: Cambridge University Press, 1996)..
 See Padgett, Science and the Study of God, for a fully developed argument for these points.
 These comments from Evans and Brown were made orally at the incarnation Summit. See further, C. Stephen Evans, The Historical Christ and the Jesus of Faith (New York: Oxford University Press, 1996), for his views on naturalism in history.
. R. Niebuhr, Faith and History (New York: Scribners, 1949).
. Another example would be D. Z. Phillips, following some of Wittgenstein’s ideas (see Phillips, The Concept of Prayer [New York: Shocken, 1967], 14). Through his Viennese education Wittgenstein himself was influenced by Kierkegaard and Kant.
. See e.g. book I, ch. II, “The Speculative Viewpoint” in his Concluding Unscientific Postscript, trans. D. F. Swenson (Princeton: Princeton University Press, 1941), 49-55, which SK wrote under a pseudonym.
. E. Hoskyns and N. Davey, The Riddle of the New Testament (London: Faber & Faber, 1931), 10.
. For two brief introductions to Wittgenstein and religion, see John Hyman, “Wittgensteinianism,” in P. Quinn and C. Taliaferro (eds.), A Companion to Philosophy of Religion (Oxford: Blackwell, 1997), 150-8, and Garth Moore with Brian Davies, “Wittgenstein and the Philosophy of Religion,” in Philosophy of Religion, ed. Davies (Washington, D.C.: Georgetown University Press, 1998), 27-33.
. C. Barrett, ed., Lectures and Conversations on Aesthetics, Psychology, and Religious Belief (Berkeley: University of California Press, 1966), 57.
. Lectures, 58, his italics.
. A useful beginning in this regard is James Kellenberger, The Cognitivity of Religion (London: Macmillan, 1985), which includes a balanced discussion of “Neo-Wittgensteinian” philosophers of religion like D. Z. Phillips.
. See Hick, The Myth of God Incarnate (London: SCM, 1977), and more recently, “The Logic of God Incarnate,” Religious Studies 25 (1989), 409-23.
. See, e.g., S. T. Davis, Logic and the Nature of God (London: Macmillan, 1983); D. Brown, The Divine Trinity (London: Duckworth, 1985); T. V. Morris, The Logic of God Incarnate (Ithaca, N.Y.: Cornell University Press, 1986); R. Sturch, The Word and the Christ (Oxford: Clarendon Press, 1991), and R. Swinburne, The Christian God (Oxford: Clarendon Press, 1994).
. Sometimes Peirce called this the “method of hypothesis.” See, for example, his Elements of Logic, book III, section B, chapter 5, in C. Hartshorne and P. Weiss, eds., Collected Papers of Charles Sanders Peirce, (Cambridge, Mass., Harvard University Press, 1965), vol. 2, par. 641-4.
. Even philosophers have sometimes misunderstood the logic of retroduction. In formal, symbolic terms, (where E stands for evidence, and H stands for some hypothesis), the logic of retroduction is not: If H1 then E1. If that were so, then retroduction would commit the fallacy of affirming the consequent. Rather the logic (in formal terms) is represented by:
1. If E1 then P(H1)>P(H2).
Here P(x) stands for “the probability of X,” and > as “greater than.”
2. If E2 then P(H2)>P(H1).
The standard probability calculus puts this more eloquently as: P(H1/E1&K)>P(H2/E1&K) where K stands for our background knowledge. See further, R. G. Swinburne, An Introduction to Confirmation Theory (London: Methuen, 1973).
. “Theodosius’ Horse,” Church History 34 (1965), 251-61, citing 253.
. See my chapter on the historical Jesus and article on the mutuality of theology and science, both cited above (n. 24).
. This claim is controversial but, on the historical evidence, eminently defensible. For a survey of the issues, see David Aune, “Magic in Early Christianity,” Aufstieg und Niedergang der r�mischen Welt (Berlin, New York: de Gruyter, 1972-2000), 2/23.2, cols. 1507-37, or H. C. Kee, Miracle in the Early Christian World (New Haven: Yale University Press, 1983).
 See, e.g., Larry W. Hurtado, One God, One Lord: Early Christian Devotion and Ancient Jewish Monotheism (Philadelphia: Fortress, 1988).
. This paper was read at the incarnation Summit at St. Joseph’s Seminary, Dunwoodie, NY, and at Leeds University. My thanks to Steve Davis and Gerry O’Collins for the invitation to the summit, and their helpful comments upon an earlier draft of this essay. I thank my friend Nigel Biggar of Leeds for arranging my lecture there, in a most congenial atmosphere for philosophical discussion. I am also grateful to those who commented upon the paper during these meetings, including Brian Hebblethwaite, David Brown, Robin Le Poidevin, Gordon Fee, Carey Newman and Steve Evans. Finally, my thanks to my student assistant, Jeanne Dahl, for help with the final published version.