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Mathematical models in social science are like fables …that we read to get insights into the social world in which we live.
—Roger Myerson
The word “model” sounds more scientific than “fable” …although I do not see much difference between them.
—Ariel Rubinstein
Many political scientists will regard my epigrams as off-the-cuff comments, to be humored, perhaps, but not taken seriously. That dismissive judgment is a mistake. I defend the view that in making and deploying formal models we construct fables and we do so in order to convey relatively simple lessons, morals, or “truths.” This in no way subverts the scientific aspirations that many in the discipline embrace. Instead, my arguments help clarify those aspirations.
I claim no originality for the suggestion that we think of models as fables. Prominent game theorists repeatedly draw this comparison, although without pursuing their remarks in a systematic way. 1 But their observations converge with more sustained arguments advanced by philosopher Nancy Cartwright (1999, 2010). As a point of departure, I believe we ought to take these accomplished economists and philosophers at their word when they insist that when we make formal models, we really are constructing fables.
In pursuing this line of inquiry, we will depart markedly from what I call “the standard rationale.” This is a view that prevails in contemporary political science. It goes like this: (1) we rely on formal models to generate predictions, (2) we treat these predictions as empirical hypotheses, and (3) we seek to test these hypotheses against evidence derived from the “real world.” Models, according to the standard rationale, are valuable for directly empirical purposes. The considerable distance between the standard rationale and the models-as-fables view poses no difficulty, I will claim, just insofar as the former, on examination, is thoroughly unpersuasive.
I offer two opening caveats. First, I deal exclusively with “formal” models (e.g., game theory, social choice). I deal only glancingly with “statistical,” “causal,” or “empirical” models of various sorts or with the diverse relationships between these and models of the formal sort. 2 In what follows, “models” is shorthand for formal models.
Second, political scientists tend to assume that we properly assess the social sciences primarily, perhaps exclusively, in terms of empirical performance. This shared premise is...