Law is not simply a matter of rules: it is also a domain of facts and objects, and explaining these facts—their nature and structure, and more in general the nature of law—is a crucial problem of jurisprudence. There is a relevant and quite intuitive sense in which social facts can be assumed to depend on the mental states of individuals. The features of this dependence, and the kinds of mental states involved, are two separate questions—the first metaphysical, the second psychological—which are, however, deeply intertwined. For this reason, legal metaphysics is inevitably an interdisciplinary research connected with cognitive psychology: it is not possible to have a clear idea of the nature of legal facts without understanding the cognitiv...