Convenientia, Argumentum Ex
CONVENIENTIA, ARGUMENTUM EX
Generally defined as an argument intended to confirm an already established principle or fact by showing the congruity of its results (cf. Summa theologiae 1a, 32.1 ad 2). The argument ex convenientia is an important and necessary theological tool in two cases: (1) in the case of acts of God that are seemingly gratuitous and might have been different or left undone with the same result, and (2) in the case of mysterious aspects of God's nature that reason cannot understand. Excellent illustrations of the argument ex convenientia are, for the first case, St. Anselm's arguments about the Incarnation, and for the second case, St. Augustine's arguments about the Trinity.
The main problem with arguments ex convenientia is the difficulty of distinguishing them from similes, analogies, and metaphors. The basis of this difficulty is that arguments ex convenientia can often be turned into analogies, and analogies likewise can be turned into arguments ex convenientia. Notwithstanding such an interchangeability, there is an essential distinction between analogies and arguments ex convenientia : the former pertain to the first operation of the mind, i.e., apprehension; the latter pertain to the third operation of the mind, i.e., reasoning. Analogies (similes and metaphors) are not intended to argue or prove something, but to clarify it; whereas arguments ex convenientia are intended to prove something by deducing it from something else, and their inability to show categorical proof does not prevent them from being real proof. Analogies take a fact for granted and try to clarify it; arguments from convenience try to establish the fact itself.
An example that clarifies this difference is that of the mystery of the Holy Trinity and the trinitarian structure of the mind. The argument from convenience tries to understand why God is a triune being and finds it reasonable, since even the human mind has a triune structure. On the other hand, the analogy accepts the fact that God is a triune being, but tries to understand what that means by comparing that triune being to the trinitarian structure of the mind.
The main danger in the use of arguments ex convenientia is that one may mistake them for arguments from necessity. When this does happen, reason, instead of the search to understand faith, turns the argument into theological rationalism. However, the fact that many Fathers and scholastics make use in their arguments ex convenientia of terms such as necessarium, necesseest, and patet should not give the impression that they necessarily are guilty of theological rationalism. They may use these terms only to bring out the convenience more forcefully.
The value of arguments ex convenientia is different from case to case. There are cases in which their value is very weak, because their congruity may be considered from different standpoints. For instance, the question of the natural perfection of Adam cannot be appreciated in the same way, on the basis of congruity, by one who holds that "the works of God are perfect from the beginning" against another who holds the contrary theory of evolution. In other cases, however, the arguments ex convenientia are almost self-explanatory, one example being Aquinas' argument proving the fitness of the Incarnation (Summa theologiae 3a, 1). In general, however, if arguments ex convenientia are not revealed, they are only probable and of limited force.
See Also: argumentation; methodology (theology); reasoning, theological; theology.
Bibliography: a. chollet, Dictionnaire de théologie catholique, ed. a. vacant et al., (Paris 1903–50) 1.1:1149–54. y.m. j. congar, ibid. 15.1:382–385, 452–456; La Foi et la théologie (Tournai 1962). a. gardeil, Le Donné révélé et la théologie (Paris 1910). m. t. l. penido, Le Rôle de l'analogie en théologie dogmatique (Bibliothèque Thomiste 15; Paris 1931).