55. To arrive at a right evaluation of what to do, the moral subject must possess a certain number of internal dispositions that serve to allow him to be open to the demands of the natural law and also be well-informed about the facts of his concrete situation. Within the context of pluralism, which is our circumstance, we are more aware of the fact that one cannot construct a morality founded upon the natural law without reflecting on the inner dispositions or virtues that enable the moralist to elaborate an adequate rule of action. That is even truer for the subject who is impacted personally by the action, and who must formulate a judgment of conscience. So it is not unexpected that there has been a contemporary revival of a “morality of virtue” inspired by the Aristotelian tradition. Insisting thus on the moral qualities demanded by an adequate moral reflection, the important role that diverse cultures attribute to the figure of the sage is recognized. He enjoys a special capacity of discernment by the measure in which he possesses the inner moral dispositions required to formulate an adequate ethical judgment. A discernment of this type should characterize the moralist when he is forced to concretize the precepts of the natural law, just as every autonomous subject is required to do to make a judgment in conscience and to formulate an immediate concrete norm to govern his action.
56. Morality cannot therefore limit itself to producing simply rules. It must also favor the formation of the subject affected by the action so that he is able to adapt the universal precepts of the natural law to the concrete conditions of existence in different cultural contexts. Such capacity is assured by the moral virtues, in particular, that of prudence, which integrates the singularity needed to guide the concrete act. The prudent man should possess not only knowledge of the universal, but also knowledge of the particular. To indicate well the actual character of this virtue, St. Thomas Aquinas does not hesitate to say: "If one is to have only one of the two kinds of knowledge, it is preferable that he have knowledge of the particular reality, since it is closer to the action before him.”(58). Through the use of prudence one tries to penetrate with reason the contingency that is always mysterious so as to adapt oneself to reality in the most precise manner possible, to assimilate the multiplicity of circumstances, to record the most faithfully as possible a unique and indescribable situation. Such an objective requires diverse operations and abilities which prudence must actuate.
57. Nevertheless, the individual should not lose himself in the concrete and in the particular, as is the approach of "situation ethics." He should discover the "straight rule of action" and establish an adequate rule of action. This straight line is derived from first principles. He should think on the first principles of practical reason, but must also rely on the moral virtues to open and render the promptings of his will and sensible affections connatural with the various human goods. It is this which indicates to the prudent man what ends he ought to pursue in the daily flow of his life. At this point the individual will be in a position of formulating the concrete rule that is required and of conferring upon the given action a light of justice, of fortitude, or of temperance. One may speak here of the exercise of an "emotional intelligence": the rational powers, without losing their specificity, are exercised within the the emotional field, so that the whole of the person is pledged to moral action.
58. Prudence is indispensable to the moral subject because of the flexibility required in the adaptation of the universal moral principles to diverse situations. But such flexibility does not authorize seeing in prudence a sort of easy compromise with respect to moral values. To the contrary, it is precisely through prudent decisions that the concrete requirements of moral truth are expressed in the subject. Prudence is a necessary passage for authentic moral obligation.
59. Within a pluralistic society such as ours, this a perspective is invested with an importance that is unable to be overestimated without undergoing considerable damage. In fact, this perspective was born from the fact that moral science cannot supply to the subject agent a rule that can be applied adequately and, as it were, automatically to a concrete situation; only the conscience of the subject, the judgment of his practical reason, can formulate the immediate rule of action. But at the same time, this perspective does not ever abandon conscience to subjectivity alone: conscience opens itself to the moral truth in such manner that its judgment is adequate. The natural law is not able therefore to to be presented as a ready-fashioned ensemble of rules that are imposed a priori upon the moral subject, but is an objective source of inspiration for the process, eminently personal, of making decisions.
(58) Cf. Id., Sententia libri Ethicorum, Lib. VI, 6 (ed. Leonina, t. XLVII, 353-354): "Prudence does not consider only the universal, in which there is not action; but should know the particular, since it is active, that is to say, the principle of action. Now, the action is on the particular. So some that do not have universal knowledge are very active in some special reality in which they have a universal knowledge, because they have the experience of this particular reality. . . . Since therefore prudence is active reason, it is necessary that the prudent man have knowledge of both, namely of the universal and the particular; or, if he is to have one alone, it is better that he have knowledge of the particular, since it is is closer to the action. (Prudentia enim non considerat solum universalia, in quibus non est actio; sed oportet quod cognoscat singularia, eo quod est activa, idest principium agendi. Actio autem est circa singularia. Et inde est, quod quidam non habentes scientiam universalium sunt magis activi circa aliqua particularia, quam illi qui habent universalem scientiam, eo quod sunt in aliis particularibus experti. [...]. Quia igitur prudentia est ratio activa, oportet quod prudens habeat utramque notitiam, scilicet et universalium et particularium; vel, si alteram solum contingat ipsum habere, magis debet habere hanc, scilicet notitiam particularium quae sunt propinquiora operationi)".