Nnadiebube Journal of Social Sciences

This article critically examines Thomas Aquinas’s theory of natural law and its significance for the foundations of moral and legal order. It argues that Aquinas offers an integrated account in which eternal law provides the ultimate order of reality, natural law makes that order accessible to rational creatures, practical reason directs human action toward objective goods, and human law translates general moral principles into concrete social regulations. Particular attention is given to Aquinas’s understanding of law as an ordinance of reason for the common good, his account of the natural inclinations and the first principle of practical reason, the relationship between natural and human law, and the concept of determinatio. The study further examines the implications of natural law for moral objectivity, virtue, human dignity, justice, political authority, and the evaluation of unjust laws. In engaging contemporary scholarship, the article situates Aquinas within the broader natural-law tradition represented by Aristotle, John Finnis, Jean Porter, J. Budziszewski, Russell Hittinger, Martin Rhonheimer, and Alasdair MacIntyre. The analysis shows that Aquinas avoids both moral relativism and an understanding of positive law as morally self-sufficient. Although positive law possesses a legitimate sphere of discretion in determining how general principles apply to particular social circumstances, its legitimacy ultimately depends upon reason, justice, and the common good. The article concludes that Aquinas remains philosophically significant because he provides a coherent framework for relating human nature, practical reason, moral obligation, political authority, and legal legitimacy.

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