Father Pegues concludes his exposition of the virtue of prudence by discussing sins opposed to prudence on account of excess. Two types of sins opposed to prudence on account of excess are false prudence and false solicitude.
False prudence is “that complexity of sins which vitiate the true character of prudence by seeking an end that is bad, or by exceeding the limits of prudence in choosing wrong means to an end.” Prudence of the flesh is a kind of false prudence, for “it consists in disposing our life in the interests of the flesh which is served as an end.” It is a mortal sin “whenever the interests of the flesh are looked upon as the last end; if, however, these interests are not looked upon as the last end and as not ordained to the last true end of human life, then the sin is only venial.”
Other kinds of false prudence exceed prudence as regards the means employed. Three sins of this type are slyness, deceit, and fraud. Slyness is “that false prudence which consists in using false and deceitful means whether it be question of a good or of a bad end for which they are used.” Deceit consists in “effecting by words or by deeds the projects suggested by slyness.” Fraud also concerns projects suggested by slyness, but it is “confined to the execution of some project by deed only.” Slyness, deceit, and fraud differ from lying in this: “The lie takes falsehood as its end; whereas the three sins above mentioned take it as a means. If by chance the latter deceive, this is only to gain some end in view. It follows that lying is a special sin in the order of the moral virtues, a sin that is in opposition to the virtue of telling the truth only; whereas slyness, deceit, and fraud can be in divers genera of sins.”
False solicitude is “that solicitude the sole object of which is the seeking after temporal things, or after some empty vanity, or that which makes one fear inordinately the loss of these things.” Good solicitude, by contrast, is “that solicitude for temporal things that seeks them in a moderate way, by ordaining them to the end of charity, and by trusting to the providence of God. . . . Solicitude is good when it contents itself to provide for the future in so far as the future depends upon those things which should occupy the attention here and now; leaving alone for future consideration the things that are future.”
Quotations from Thomas Pegues, Catechism of the “Summa Theologica” of Saint Thomas Aquinas, trans. Aelred Whitacre (New York: Benziger, 1922).