Hume and contemporary Humeans contend that moral sentiments form the sole and sufficient basis of moral judgments. This thesis is criticized by appeal to Hume's theory of justice, which shows that basic principles of justice are required to form and to maintain society, which is indispensable to human life, and that acting according to, or violating, these principles is right, or wrong, regardless of anyone's sentiments, motives or character. Furthermore, Hume's theory of justice shows how the principles of justice are artificial without being arbitrary. In this regard, Hume's theory belongs to the unjustly neglected modern natural law tradition. Some key merits of this strand in Hume's theory are explicated by linking it to Kant's constructivist method of identifying and justifying practical principles (à la O'Neill), and by showing how and why Hegel adopted and further developed Kant's constructivism by re-integrating it with Hume's central natural law concern with our actual social practices.