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Potential outcomes, causal inference, and virtual history

A few years ago I picked up the book Virtual History: Alternatives and Counterfactuals, edited by Niall Ferguson. It’s a book of essays by historians on possible alternative courses of history (what if Charles I had avoided the English civil war, what if there had been no American Revolution, what if Irish home rule had been established in 1912, …).

There have been and continue to be other books of this sort (for example, What If: Eminent Historians Imagine What Might Have Been, edited by Robert Cowley), but what makes the Ferguson book different is that he (and most of the other authors in his book) are fairly rigorous in only considering possible actions that the relevant historical personalities were actually considering. In the words of Ferguson’s introduction: “We shall consider as plausible or probable only those alternatives which we can show on the basis of contemporary evidence that contemporaries actually considered.”

I like this idea because it is a potentially rigorous extension of the now-standard “Rubin model” of causal inference.

As Ferguson puts it,

Firstly, it is a logical necessity when asking questions about causality to pose ‘but for’ questions, and to try to imagine what would have happened if our supposed cause had been absent.

And the extension to historical reasoning is not trivial, because it requires examination of actual historical records in order to assess which alternatives are historically reasonable.

Here’s Ferguson making the case that potential outcomes (in statistical terminology, the “Rubin causal model”) are particularly relevant to the study of historical causation:

What we call the past was once the future; and the people of the past no more knew what their future would be than we can know our own. All they could do was consider the likely future, the plausible outcome. . . . Now, if all history is the history of (recorded) thought, surely we must attach equal significance to all
the outcomes thought about. The historian who allows his knowledge as to which of these outcomes subsequently happened to obliteratre the other outcomes people regarded as plausible cannot hope to recapture the past ‘as it actually was’. . .

Thus, to the best of their abilities, Ferguson et al. are not just telling stories; they are going through the documents and considering the possible other courses of action that had been considered during the historical events being considered. In addition to being cool, this is a rediscovery and extension of statistical ideas of causal inference to a new field of inquiry.

I don’t know how much this aspect of Virtual History has been followed up since the book’s publication. My impression is that these are treated as purely speculative games (as in the What If? book) without a sense of the constraints of considering options that were considered at the time.

P.S. I looked up Niall Ferguson on the web and he seems to simultaneously be a professor at NYU and Harvard, a senior fellow” at the Hooover Institution (Stanford), and a visiting professor at Oxford. Perhaps he is living some virtual history himself with these 4 jobs!