A few decades ago, only isolated groups of philosophers counted the phenomenon of normativity as one of their principal interests. Rules and norms have always, of course, been in the purview of moral philosophers, who often took them as exceedingly abstract entities, if not directly metaphysical. Philosophers from the border territories of philosophy and social sciences, on the other hand, were interested in more concrete norms, namely those that emerge and survive within human societies. Philosophers of law stood between these two extremes, studying law as a matter of socially instituted norms which, however, might be seen as a projection of something more esoteric. The research programs of these groups of philosophers had little overlap. And for philosophers of mind, of language, or of science (with the exception of a few philosophers of social sciences, such as Peter Winch), norms were at most only of marginal interest. This situation has changed hugely over recent decades. I think the catalyst was the interest in rules and norms within the philosophy of language, which was kindled by the ongoing reception of the later Wittgenstein. Other philosophers, like Michael Dummett and Wilfrid Sellars, also deserve part of the credit. Via philosophy of language, interest in norms invaded sections of philosophy of mind, too, and the previously isolated studies of various types of norms slowly became interconnected, if not directly integrated. No wonder that more and more general studies of the nature of rules and norms are now reaching the light of day. Andrei Marmor's Social Conventions is one of the most recent contributions. Marmor sees a social convention as a specific kind of norm characterized especially by its arbitrariness. More precisely, a rule is conventional, according to the author, iff (i) some people follow it; (ii) they have a reason to follow it; and (iii) there is an alternative rule that they could have followed for the same reason. The point of departure for Marmor's analysis is David Lewis's theory of convention F1F, which, however, he considers too narrow and hence extends it considerably. Lewis's idea is that norms result from certain spontaneous processes by which society reacts to coordination problems...