I recently posted on Facebook that I have taken to suggesting to doctoral students that they read Agatha Christie's Murder on the Orient Express, as I consider the way that she depicts Poirot solving the case to exemplify the way in which historians should go about doing the work of history. There was some interest expressed in further explication of this statement, so here it is. (Warning in advance: the antepenultimate and ultimate paragraphs contain spoilers. Best not to read if you have not read Murder on the Orient Express or seen any of its various adaptations).
As many readers will no doubt know, the Lonergan Research Institute houses the Lonergan Archives. A big part of what we do is respond to electronic requests for scans and the like, so when I took over as Executive Director last year I spent some time familiarizing myself with the contents of the archives. I was surprised to discover the number of murder mysteries among Lonergan's books. Most of the murder mysteries found in the archives were published in the sixties and seventies. This is significant, because it is during this period that he fell more fully under the influence of the philosopher of history, R.G. Collingwood (my friend and colleague Jordan Ryan has looked into when Lonergan really began to read Collingwood heavily: IIRC, there's only one reference to Collingwood in Insight in 1957, but by Method in 1972 Lonergan is devoting whole sections to C.'s thought). Why is Collingwood significant in regard to the murder mysteries? "Historian as detective" is a significant theme in Collingwood's work, to the point that he develops his own miniature detective fiction to illustrate certain of his arguments. As far as I can tell, Lonergan's interest in murder mysteries increased in parallel with his reading of Collingwood, and given Collingwood's own interest in detective fiction this doesn't seem to me entirely coincidental. I think it most likely that Lonergan's own interest in murder mysteries received significant impetus from Collingwood's references to and use of detective fiction. (It should also be noted that the mid-60s is also the time that Lonergan was convalescing from his bout with lung cancer, and thus perhaps quite plausibly engaged in more leisure reading than normal; still, even if we grant that as a factor, the fact that he turned specifically to murder mysteries remains of interest). This receives partial confirmation in the work of Ben F. Meyer, Lonergan's devotee, whose own writings on how to do history (which date from the 70s through early 90s) are both heavily influenced by Collingwood and also employ the tropes of detective fiction to illustrate key points.
Now, the above is already an example of how one does history. I start with a known fact: Bernard Lonergan owned and presumably read a good number of murder mysteries that were published in the late sixties and into the seventies. This prompts a question: why? In order to answer this, I look at other relevant data, such as what else he is apparently reading around the same time. I note that there is evidence that he was reading and influenced by R.G. Collingwood's work in the philosophy of history at the time, and also that Collingwood used detective fiction to illustrate key points. I note also that his follower, Ben F. Meyer, picks up on Collingwood's use of detective fiction and employs a similar strategy in his own work on historical method. I conclude that it is likely that Collingwood's work prompted in Lonergan an increased interest in murder mysteries.
But that leaves unaddressed why I specifically think that Murder on the Orient Express provides an exemplar of historical method.
(Here spoilers follow. You have been warned).
In the novel, a man is killed on a train. The great Belgian detective Hercule Poirot (who appeared in Christie's first novel, The Mysterious Affair at Styles, and is the character who appears most frequently throughout her stories) happens to be onboard, and as the train will be stuck in the snow for some time he's called upon to investigate the murder. He interviews his fellow passengers as well as the staff, and eventually determines that they are all lying. Even the dead man was lying, living under an assumed identity. But Poirot does not throw his hands up and say that because they are all lying we cannot know the truth. No, he asks a further question: why are they lying? And from that, he infers that they were all involved in killing the man, who had years earlier committed and gotten away with an awful crime.
If I turn to historical Jesus studies, one of my primary areas of focus, I would make an immediate parallel. Throughout the various quests for the historical Jesus the question has been which if any data in the gospels was accurate. Which claims in the gospels can be affirmed? But the lesson from Poirot is that the more important question is not "Is it true?" but rather "Why is this claim made?" There are of course cases in which a claim is made precisely because it is more or less what happened; for instance, the gospels all report that Jesus died by way of crucifixion, and almost certainly they do so because that is the case. But one might go further, and argue cogently that the gospels claim that Jesus died by way of crucifixion because the early Christians felt that the manner of his death was of theological significance; after all, what interests us is in no small part why the evangelists chose to report Jesus' death in the first place. Or to use an example where the gospels do not as fully agree: in the Synoptics Jesus cleanses the temple at the end of his ministry, in John at the beginning. So the question: why do the Synoptics report this action at the end of Jesus' ministry and John at the end? I note that all the gospels agree that the cleansing occurred at Passover. I also note that the Synoptics only depict Jesus going up to Jerusalem once for Passover. I note that John depicts him going up to Jerusalem for several Passovers. An insight: given that the Synoptic Gospels only narrate one trip to Jerusalem for Passover, they have no choice but to situate a Passover cleansing in that particular trip; conversely, as John narrates multiple trips to Jerusalem at Passover during the ministry, he has the option of situating the cleansing at any of these. I thus advance an hypothesis: the Synoptic decision to situate the cleansing during Jesus' final week is a result of their prior decision to narrate but one trip to Jerusalem. But we still need to explain why John situates it at the beginning? And this is where it gets more interesting: there is no comparably compelling explanation on literary or one might add theological grounds as to why John situated the cleansing at the end. There is however a historical one: John situates the cleansing at the beginning of the ministry because he had reason to think that this is where it should be situated. Combined with the evidence that John is either an eyewitness or has access to eyewitness testimony, I further suggest that he had such reason because he either was present for the event or because he had access to the words of someone who was; and from this I am inclined to think that the cleansing occurred nearer the beginning of Jesus' ministry than the end.
Much like Poirot, I conclude that three of my sources are less than fully accurate. (I wouldn't say they are lying: I would say rather that they are constrained by their own narrative decisions). But the precise content of that inaccuracy is a significant clue to what actually happened. And that's why Mrs. Christie still rewards reading.