I've been thinking a bit, probably inspired by some blog posts on The Economist, on why I've been so focused on history of late. The big impetus was probably from some of my grad classes where we focused on some books written fairly recently by fairly prominent scholars. What I found remarkable was that they would use a very narrow slice of history to build up elaborate theories on with little reflection on whether their data point was coming from a special case or whether they had enough to reflect the general case. In particular, I found that some fairly influential books drew heavily from European history, from about the 18th century to today, and used this to build general theories of international relations that supposedly can be applied to policy analysis today and on into the future.
This, frankly, shocked me. It doesn't seem like you need to know that much history to realize that the European system was a pretty unique historical development. Sure, some authors would show off their classicism by talking about the Hellenic period as well, but it should be pretty clear these are special cases and not an adequate basis for general theories about state interaction and international relations. However, these assumptions about whether or not the system was generalizable didn't seem to be seriously questioned. When writing about say, the importance of military power, it should be obvious that states small enough to be overrun in a short campaign are going to have intrinsic differences to states that are massive in size. It also shouldn't be too much of a leap to think that states that derive legitimacy from a hereditary military aristocracy are going to have different ideas about the international system from states firmly rooted in institutional authority. Yet, these concepts are only infrequently brought in, even when data is being drawn from very long periods of time.
So, what's the point of this? Basically, that most of the common ideas being tossed around show little reflection on how broad they should be. Are these ideas that should be thought of as generally applicable, or are they ideas that describe how actions function within a narrowly defined social and institutional relationship. Does a given economic proposition describe a situation that applies among any group of people trading with each other, or does it only work if everyone involved shares similar cultural ideas? Can the theory deal with changing institutions or does it presuppose a narrow set of institutional arrangements? Does the theory cover the ability of one set of actors, say the state and individuals, to change each other, or does it hold arrangements static? For an example of this, can an economic theory deal with the shift from a state that legislates for markets to be run by family groups that then changes to an economy run by corporate groups? Or does it not deal with this level of interaction?
So what does this long list of questions have to do with history? Simply that we can look over history to know what types of things have changed, where different types of institutions have been in place and have some idea about the limits a given perspective has on understanding problems and know to ask how that perspective deals with these shifts. If a given perspective assumes a certain type of economy, say a largely industrial economy, we should know to ask if it can accurately describe an economy composed differently, say an agricultural or service economy. If it doesn't work for that than we should be aware of its limits and not ask it do more than it is capable of. Often however, it does not seem that people advocating for a particular perspective have thought deeply about whether or not their perspective actually attempts to deal with certain aspects of reality. You may have a brilliant economic theory that describes in detail the efficient interaction of markets, but is there actually any theory of the state there or does it just have assumptions about the state? This question is important because it is important to distinguish between advocating not for the best structure of the state but simply advocating for the structure of the state assumed by the theory. If there is no actually theory about the state and the effects of state structure on the rest of the world than an economic theory has no place in a debate about the proper structure of the state. It has nothing to actually say on the subject except what kind of state is necessary for the theory.
To get back to the original topic, history provides us with the observations we need to know all the ways in which societies have changed. While any given theory or explanation of why a policy is favored doesn't require every detail to be incorporated, it is important to have an idea of all the things that have changed in the past to be humble about any suggestion since it can have effects in areas not really dealt with by a theory. A major pitfall people suffer is to advocate for the conditions of a theoretical perspective they are knowledgeable about rather than to advocate for a reasoned response to the actual issue under consideration.