H.L.A. Hart was the pre-eminent legal philosopher of the twentieth century. As a scholar he single-handedly reinvented the philosophy of law and revolutionized our understanding of law as a social institution. Hart's approach to legal philosophy was at once disarmingly simple and breathtakingly ambitious, combining the insights of the Utilitarian tradition and the new linguistic philosophy of J.L. Austin and Ludwig Wittgenstein. He sought to elucidate...