Abstract
Several philosophers have argued that “constraints” constrain (and thereby explain) by virtue of being modally stronger than ordinary laws of nature. In this way, a constraint applies to all possible systems in a broader (i.e., more inclusive) sense of “possible” than the sense in play when we say that the ordinary laws of nature apply to all physically possible systems. Explanations by constraint are thus more general, more broadly unifying, than ordinary causal explanations. Putative examples of constraints are often drawn from physics. The great conservation laws (of energy, mass, momentum, etc.) are posited as being constraints because they are modally stronger than the various particular force laws they govern. This greater modal strength is reflected in the truth of various counterfactual conditionals according to which the conservation laws would still have held even if there had been different (or additional) forces. The conservation laws thereby explain why there are no perpetual motion machines, for instance. When we look at what explains the conservation laws, we find further constraints, such as the symmetry principles that (in a Hamiltonian dynamical framework) entail and are entailed by the conservation laws. As constraints (i.e., as meta-laws), the symmetry principles are modally stronger than the first-order laws, and their greater modal strength is again manifested in the truth of various counterfactual conditionals. For instance, the first-order laws would still have been symmetric under temporal translation even if there had been additional kinds of forces. All of these examples are drawn from physics. This raises the question of whether constraints, meta-laws, non-causal explanations by constraint, and so forth are plausibly present in the social sciences as well. I will argue that they are. I will look at some potential examples from linguistics and other human sciences and see whether they are analogous to the examples that I have just mentioned from physics. On this view, there are no languages of certain sorts because no such language is possible–in a broader sense of “possible” than a causal explanation could underwrite.
