Despite being interested in figuring out exactly what economics is, really, I have to confess that I don't really care about the common question "is economics a science?". Trying to answer it seems to tie people in knots, and I don't think the question by itself is very important. However, I just found a nice article on the subject which set me thinking.
My economics education was very essay-centric, and, perhaps paradoxically, I think was a good means to understanding what it takes to be "scientific" in a social science. A good essay has to contain more than raw emotion, but similarly should not avoid interpretation. It's equally difficult to argue using facts alone as it is to argue without them.
Is "good economics" the same? A theorem or result is, by nature, empty in itself - it's just a logical chain from start to finish. With the right starting point, you can "prove" anything; with an unproveable starting point, you're really in business. However, for the result to matter, it has to be put in context. What does it mean? Maybe it's semantics, but the search for meaning - the interpretation - is the birth of a normative judgment, still value-free but certainly pushing that label as far as it can go, before the true normative judgments of what we want are made.
The separation of the "scientific method" of economics and the use of its results must be sacred. The former, done from a position of honesty, can never be "wrong", since it's just logic. Why, then, must we introduce interpretation at all? The best reason to do so is the problem of "underdetermination", the idea, captured in the Friedman quotation I mentioned in a previous post, that if there exists another theory at least as consistent with the evidence, our theory is "underdetermined": all, perhaps, related to the problem of the unproveable starting point.
The underdetermination issue is, I think, especially relevant to theories which rely on behavioral assumptions, given that we know that humans are (sometimes) capable of being pretty nuanced in their behavior. Whether or not any scientific theory can be airtight is up for debate; in economics, I am convinced that no theory can be airtight. That's not to say we can't be nice empiricists and check predictions against evidence like scientists do, but it is to say that the alternative, consistent theories must be addressed before we can cross the line from positive science to normative policy. I have to show that my theory can be right, but also argue that mine is the most right, especially if I want to take my theory from the sterile, all else equal, scientific vacuum into inference about the real world.
Just like a debater or an essay writer, any position I occupy can be attacked, and defense is the only response that will preserve that positive, scientific position. If we can prove anything, if any hypothesis is underdetermined, then whether or not economics can be called a science, the scientific method alone won't be enough. Somewhere between that scientific method and the politicking of normative selection lies that subtle gray area which all of our correct, consistent theories must cross. There we must decide what we want to use them for, and how they should be received; the "useful" ones must be the only ones allowed to survive.