Dissertatio haec, doctrina Thomae Aquinatis de lege naturali innitendo, quaestionem movet, quomodo conceptus autonomiae personali pro fundamento doctrinae ethicae sumi possit. Hoc ideo possibile esse videtur, quia lex naturalis, ut dictamen rationis, fines determinat, ad quos unusquisque homo in sua vita seipsum rationabiliter ordinare potest. Ex quo etiam ratio patet, cur in vita humana moralitati obsequendae opera danda est. Est enim homo “animal sociale”, cuius igitur finis naturalis est (praeter alia) in societate humana vivere. Ex hoc duo principia possunt inferri: 1) nulli est nocendum; 2) ius suum cuique est distribuendum. Modus tamen applicandi harum praeceptorum, sicut et ceterorum praeceptorum legis naturalis, a persona agentis eiusque historica et sociali situatione dependet.

Starting from Aquinas’s natural law theory, the article discusses in which way one can ground an ethical theory relying on the concept of personal autonomy. This is possible because natural law, as a law of reason, determines the ends for which every individual human being reasonably may strive. In this context, it is also possible to justify the role of morality in human life. This is due to the nature of man as a social animal whose natural ends include a life in a human community. From this one can infer the two principles, not to harm others and to attribute his right to everybody. The application of those rules, as of any other rule of natural law, depends upon the person of the agent and his historical and social situation.