Abstract
There is a substantial amount of discussion in the philosophical literature on multiscale modeling in physical and material contexts. But there is less such discussion when it comes to the social sciences. This paper earmarks economics as a promising area for multiscale exploration for a number of reasons. First, there’s a sense in which things that go on at one scale on their own do not reduce to what goes on at another, though goings-on at one scale may contribute to goings-on at another. Formal results such as the Sonnenschein-Mantel-Debreu theorem and the questionable success of the microfoundations program provide at least two prima facie reasons we should be suspicious of reductionist attempts in economics. The next natural step would be to consider how it is that economists use multiple models together. Second, economists in actual practice, such as those at central banks, often really do use multiple models in order to achieve monetary policy aims. The literature is now over trod with commentary about the representational capacity of these (often idealized) models, so much so that not only is the discussion often quite divorced from economic practice, but it also makes the possibility of a realist interpretation of economics look rather tenuous. This paper shifts its attention to the role of models not just as representational devices, but also as devices for the construction of performative narratives. Models, when deployed in policy analysis, are part of the effort to construct coherent narratives that help guide action. This is an enterprise that often requires different parties to coordinate their expertise and resources. This role requires that models take on both the role of being explanatory — being able to be the kind of tool that people can use to ask what-if-things-had-been-different or why-questions — and performative — being the kind of tool that economists can use to effectively enact changes in the world. Doing so will highlight a number of features about economic models in particular that has escaped much of mainstream philosophical attention — for instance, why it might be that economic models furnish 6 how-actually (as opposed to merely how-possibly) explanation. The multiscale modeling framework, I propose, is one promising way of grounding this conception of model usage. To this end, I examine two case studies. One is explicitly multiscale: integrated computable general equilibrium and microsimulation modeling strategies, with particular attention to income distribution effects. The second is more implicit: I examine the process by which the U.S. Federal Reserve, via the construction of the Greenbook (now Tealbook) conditional forecasts which are then distributed at the Federal Open Market Committee meetings for discussion, offers policy recommendations. Finally, I suggest that these considerations actually point to a kind of pragmatic realism as the right attitude to have towards many economic models.
