ABSTRACT
Understanding legal customs is a matter of balancing an external factor against an internal one: the former a practice, the latter a belief about the normative character of that practice. Both elements must be taken into account and both are equally crucial. Indeed, if we focus only on the practice and leave out the belief, then we are left with a mere regularity: a sort of habit, a collection of repeated behaviors. The domain of philosophical research devoted to explaining and analyzing the metaphysics of institutional facts has a longstanding history, but only in the last decade of the 20th century, with John Searle, was it treated under the label of “social ontology”. The idea that legal ontology can be described as “three-dimensional” is not new in the philosophy of law. Given that this analytical framework is being applied here to customary law, the example of chess needs to be further qualified.
