Sometime commenter and (as Henry Farrell says) one of the Internetses’ smartest guys Cosma Shalizi has kindly listed my Blessed Among Nations on his list of “Books To Read While the Algae Grows in Your Fur” (also known, perhaps less slothishly, as “Books I’ve read in the last month or so and feel I can recommend”). So I think it’s only fair to respond to his query, which is so astute that only my colleague Kathy Olmsted has previously raised it. To wit:

Rauchway seems to find it unproblematic that a certain set of institutions should form Back In The Day, when they fit conditions … and then tend to survive later, when they did not fit so well. But I would like some explanation of why adaptive processes had an easier time working in the earlier period, as opposed to the later one.

Here is what I think I think, if I understand the question correctly:

In the earlier period the US was subject to evolutionary pressures in its environment that encouraged it to develop certain policies (those having to do with controlling and directing immigration and capital investment) but not others (those laying the foundation for a modern welfare state).

At around 1920, that environment ceased to exist, and so did those evolutionary pressures. But they were not replaced by an immediately imperative new set of pressures, because in this new environment the US was not only, if you like, top predator, but top predator in a damaged ecosystem (if I remember my Alfred Crosby-esque arguments correctly).

So under these circumstances it did indeed keep its old habits, and there was no immediate direct pressure to change them. But the old habits did not make the US a particularly good steward of this environment, nor entail a restoration of its previous vigor. Instead they caused a progressive deterioration of the environment of the 1920s, and then a precipitous and disastrous collapse beginning in 1929.

Those of you wishing extra credit can flesh out the climate-change analogy on your own time.

I would go further: the new, much more direct evolutionary pressures of the 1930s did indeed work on the US just as one would imagine they should, and encouraged changes in American institutions accordingly. But if we want to talk about that, we need to talk about a different book.