The measure of indebtedness
A pressing question remains: what is the measure of indebtedness?
The general answer, of course, is that I am indebted to others in the amount of my supèrflua—that is, in the amount by which my property exceeds what I need. This answer requires specification.
No doubt the line between necessitas and supèrflua must always remain elusive on the individual side of the equation, but conceptually there is a measure. The measure is self-sufficiency, as Aquinas explains in his commentary on Aristotle’s Nicomachean Ethics.91 Self-sufficiency, in turn, draws the line between necessitas and supèrflua in two ways.
First, the optimal point is reached when “a truly happy” person “is undisturbed by the things that are unnecessary even though attainable.”92 In other words, we arrive at the outer limit of necessitas when the acquisition of additional goods would do nothing to increase the happiness of one whose desires are “controlled by reason.” Question 2, Article 1, of Prima Secundae is quite specific, enumerating the items that “serve as a remedy” for natural wants. They are “food, drink, clothing, vehicula, dwellings, and such like.”
Secondly, there is a point at which the accumulation of property begins to undermine, rather than promote, self-sufficiency. “Superabundance,” Thomas writes in his Ethics commentary, “makes people less self-sufficient since a man must have the help or service of many servants to guard and manage excessive possessions.”93
Necessitas on the community’s side has three components: “that the community be established in the unity of peace,” that the community “be guided to act well,” and “that, through the industry of the ruler, there be a plentiful supply of those things necessary to living well.”94 Necessitas and supèrflua provide the measurement of these components as well. To return to this chapter’s starting point—Article 8 of Question 66—if “princes” exact property from their subjects “unjustly,” they are bound to make restitution. This means that if they take something that is not “due” them (indebitc extorqueant), they have violated justice, measured by aequalitas, determined by the line drawn between necessitas and supèrflua. Thomas’ high view of individual appropriation seems to reflect his concern that the ruler could become greedy and rapacious. In a similar way, the necessitas of the state serves as a constraint on the limitless acquisitiveness that can beset individuals. The state and the individual do not simply keep each other honest, as we would say now. They serve as reminders to each other that the acquisition of property’ by either is always only instrumental; it must never become an end in itself.
To summarize the claims made here so far, ius (“right”) implies balancing in Thomas’ understanding because it demands an equivalence between what is given and what is received. Ius, therefore, must take into account debitum if it is to be an objective, moral obligation. Debitum in the economic sphere is measured by necessitas, which is worked out, in turn, by either self-sufficiency or the common good. Before turning to the implications of balance in Thomas’ system, this chapter places the interplay of necessitas and supèrflua in historical context.