Interpersonal Commands and the Imperium-Praeceptum Debate

THE CONCEPT OF “COMMAND” is central to the moral psychology of St. Thomas Aquinas. He has much to say, for instance, on the role of imperium (and related concepts, such as the actus imperatus) within his theory of human acts. He also describes prudence as consisting in part in an act that he calls the praeceptum. Yet St. Thomas never clarifies the relationship between these terms, both of which we could translate as “command.”

In the second half of the twentieth century, certain Thomists, such as Odon Lottin and René Gauthier, noted this problem and entered into a debate regarding the relationship (and possible equivalence) between these two Latin terms in the thought of St. Thomas. The discussion reached considerable proportions, to the point that more recently Michael Konrad referred to it as an “old cross of the Thomists.”¹ Scholars today still refer to the discussion, whether they consider it resolved² or wish to further the debate,³ and often in order to point to its nuances and its wide-ranging consequences.⁴

The problem arises from two sets of texts of St. Thomas in the Prima secundae, especially when read in translation. In one set of texts, the most important of which is question 17, he explains that in a human act, the act of choice (electio) is followed by the “command” (imperium) of the will.⁵ That is to say, a person first chooses a course of action to be followed and then commands the different powers of the soul to begin executing the action. But later in the Prima secundae, he says that prudence has three distinct acts: primus est consiliari, secundus iudicare, tertius est praecipere. The third and most important of these, praecipere, is often translated as “to command.”⁶ The question, then, arises: What is the relationship between the “command” (imperium) of the will that follows choice and the “command” (praeceptum) of prudence, which presumably must precede choice? Although in a few texts St. Thomas actually uses the expressions imperium vel praeceptum⁷ and praecipere vel imperare,⁸ he never addresses this question explicitly. The semantic proximity between praecipere and imperare has thus led many Thomists⁹ to hold that these two terms are ultimately equivalent, thus identifying the third act of prudence with the act of command of the will that follows choice.

This identification is not without its problems, however. On the basis of the first group of texts, most Thomists agree that imperium follows electio—in other words, that choosing must take place before the will can command the different powers of the soul to execute the action. But if the praeceptum of prudence is equivalent to the imperium of the will, then it would seem to follow that the third act of prudence is posterior to electio, rather than prior to it. This hypothesis is problematic because prudence is required for making a good choice.¹⁰ That is to say, one would not truly be prudent if one were to defer the prudent judgment until after making a choice; far from being prudent, such a course of action would be rather reckless. Aware of this conundrum, Lottin and Gauthier questioned the identity between the praeceptum of prudence—which must precede choice—and the imperium of execution—which must follow choice. Thus began the controversy.

The discussion in the twentieth century is so extensive that an exhaustive review of the literature would require its own study. We have noticed, however, that the lengthy debates of recent decades have generally omitted references to a few texts where St. Thomas describes imperium and praeceptum within the context of interpersonal commands, that is, of one person commanding another. This is seen especially—though not exclusively—in St. Thomas’s discussion of divine precepts in his Commentary on Psalm 18, a text that has been largely ignored in the discussion.¹¹ These texts which speak of interpersonal commands can shed much light on the relationship between praeceptum and imperium in St. Thomas’s corpus. Our goal is to make...