Eugenio Bulygin is a distinguished representative of legal science and legal philosophy as they are known on the European continent - no accident, given the role of the civil law tradition in his home country, Argentina. Over the past half-century, Bulygin has engaged virtually all major legal philosophers in the English-speaking countries, including H.L.A. Hart, Ronald Dworkin, and Joseph Raz. Bulygin's essays, several written together with his eminent colleague and close friend Carlos E. Alchourrón, reflect the genre familiar from Alf Ross's On Law and Justice, Hans Kelsen's Pure Theory of Law, and Georg Henrik von Wright's Norm and Action. Bulygin's wide-ranging interests include most of the topics found under the rubric of analytical jurisprudence - interpretation and judicial reasoning, validity and efficacy of law, legal positivism and the problem of normativity, completeness and consistency of the legal system, the nature of legal norms, and the role of deontic logic in the law. The reader will take delight in the often agreeably unorthodox character of Bulygin's views and in his hard-hitting arguments in defence of them. He challenges the received opinion on gaps in the law, on legal efficacy, on permissory norms, and on the criteria for legal validity. Bulygin's essays have been wellnigh inaccessible in the past, appearing in specialized journals, often in Spanish or German. They are now available for the first time in an English-language collection.