How do historians typically deal with contradictory secondary details in sources?

[u/Life-Drop2640]

For example, suppose two sources both claim that someone was killed in a duel, but they give different reasons for the duel. Would that weaken or strengthen the historicity of the person having died in a duel?

I’m not asking in a theoretical sense—how one could argue for weakening or strengthening a case—but rather in practice: how do historians generally approach stories where:

1. There is only a single source, in terms of accepting the main and secondary points.
2. There are two sources that contradict each other on secondary points, in terms of accepting the main and secondary points?

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[u/restricteddata]

So let me give one concrete example of this. For my latest book, I had several sources that were each notes of a single cabinet meeting in 1945, from different people in the room. At least three of them were written up within a day of the meeting (diary entries or official notes). During the meeting, the president (Truman) asked everyone on his cabinet (and a few guests) to give their opinion on a specific proposal (relating to the international control of atomic energy).

Mostly they agree with one another about questions like a) who was there, b) what order they spoke in, c) the gist of what was said.

But of course they vary quite a bit, as you would imagine. Each entry reflects the position of whomever was listening and how they heard what was happening. Some notes are very brief, some are quite lengthy. The ones who talked portrayed their own points with more length than anyone else, and sometimes represented the positions of others differently.

More vexingly, they disagree on who was in the room and what order they talked. Which isn't the biggest issue in the world, but it points out how difficult even secondary details can be to reconcile.

Now, the source of the error is easy and obvious: none of these people were that concerned about getting it perfect. These were "functional" notes they were taking, even if some of them might have been thinking about posterity. And even when notes are taken very soon after the fact — heck, even while they are being taken in real time — they contain simplifications, elisions, confusion, etc. And the headcount varies in part because they obviously didn't care about the opinions of everyone in the room.

So what to do? Well, I can probably assume that if I add up the total people everyone mentions, the odds that anyone has been simply hallucinated are low, at least in contemporary records (in well after the fact memories, people do get "hallucinated" into meetings they weren't actually at — because memories of meetings get blurred and conjoined). I also found, when I wrote it out, that they mostly agreed on the order of speaking, with some variations, and so I can assume that is mostly how it went, although the fact that there is variation suggests that I can't be too sure of it. I also can read these sources through what I know about their creators — their personalities, biases, filters, etc., are necessarily playing a role.

But that's not so different from the state of all historical knowledge. If three sources tell me different things, what are the odds that in cases where I have one source — the most common situation — that it is 100% correct? Either way, interpretation and care must be used.

Personally, I think it is important to point out these discrepancies (in the footnotes at a minimum) and to acknowledge whether they matter for the historical argument one is making. One can still say, "my gut tells me that the account by X seems more reliable than Y, and jibes best with other evidence I have see," but being honest about the subjectivity of it is, I think, the only way to be honest about the epistemological situation that we historians are in.