By "scientific"here I mean something like doing regression analysis on a large collection of data.
Let us say we are studying the great migration out of Ireland in the middle of the 19th century. We have a hypothesis: the "cause" was the potato blight. So we collect data for each county in Ireland inluding the incidence of potato blight in that county and the percentage of population that left Ireland from that county. We run our analysis, and find that there is a stronger correlation between potato blight and emigration then there is for any other variable. We conclude that potato blight was the cause of Irish emmigration at this time.
Notice how different this is than the procedure we follow in determining, say, how the Cuban missile crisis played out. There, we would look at transcripts of meetings, speeches, intelligence reports, memoirs, and so on.
Per Noah Smith (and many others educated in a social science) the first procedure is going to yield a superior sort of understanding and causality than is the second.
It takes a lot of education to make someone believe that.
Because, I contend, the second sort of analysis rather obviously gives us a far deeper understanding of what occurred then does the first. In fact, the very reason these two different approaches are taken for these two different problems demonstrates my point rather nicely.
We resort to statistical techniques in analyzing Irish emigration precisely because we lack the time, the patience, the sources, and the mental capacity to trace out the actual history of why each particular emigrant left. I do not denigrate the value of such statistical studies; we are limited beings with limited amounts of time on our hands, and we must make do with what understanding we have the capacity to wrest from the data we have. But I think it obvious that a full historical account of why each emigrant left would be a superior form of understanding to that offered by the statistical study: after all, the statistical study leaves entirely unexplained why family A did emigrate, while family B, from the very same county, did not.
Science is great, when we don't have the time to do history.