This volume is the fi rst part of a project that aims to highlight important aspects of the complex relationship between common language and legal practice. In legal philosophy there is a well-established tradition, widespread in Englishspeaking countries (the UK, the US, and, more recently, Australia) as well as on the European continent and in Latin-American countries, that has always paid special attention to (that composite branch of knowledge that can be labelled as) the philosophy of language. Within this tradition we can identify at least two main trends. The fi rst trend, which began some time ago in continental Europe and Argentina, showed a keen interest in neo-positivism, and especially in the philosophical thought developed by Frege, Carnap, Hempel and Waissman: legal philosophers tried to import the neopositivistic theory of knowledge, and also to shape legal science as an empirical enterprise. Although the neopositivistic paradigm was revealed to be unsuitable and was dismissed (even by some of its proponents), this trend has not entirely dried up: it has partially continued in weaker forms (which, for normative language, can mainly be traced back to R.M. Hare: see Hare 1952). It has a successor in the legal logical tradition, that is, in the works of those legal scholars who employ (various types of) formal logic (and theories of possible words) in order to explain the properties of real legal systems or to develop ideal legal systems. Finally, and above all, its fundamental theses, such as the analytical–synthetic distinction, still impregnate many legal theorists’ works – pace Quine.