Section — McHugh–Callan, Moral Theology
The Prudence of the Flesh
The prudence whose end is bad is the sin of those Who counsel, judge, and direct well as to the means for securing temporal goods which they have made the supreme purpose of their lives. This sin is given the one general name, “prudence of the flesh,” from Rom., viii. 6, where the aspirations of the flesh are contrasted with the aspirations of the spirit. But it is also sometimes distinguished according to the different kinds of created things in which false prudence puts its desire, or according to the different kinds of allurements to such created goods.
(a) Thus, those who aim chiefly at internal goods (i.e., bodily pleasures, health, etc.) are said to have the prudence of the flesh, while those who long mostly after externals (such as fine clothes, jewelry, estates, etc.) are said to have the prudence of this world: “The children of this world are more prudent in their generation than the children of light” (Luke, xvi. 8).
(b) We may also divide prudence about a wrong end into earthly, animal and devilish, according to the threefold source of temptation, as was explained above in 1623.
Sinfulness of the Prudence of the Flesh
Sinfulness of the Prudence of the Flesh.—(a) If prudence of the fiesh be understood in its stricter meaning as designating the condition of those who make the things of this world the be-all and the end-all of existence, it is a mortal sin; for it is impossible that one should have two last ends or serve two masters whose interests are opposite: “The wisdom of the flesh is an enemy to God, for it is not subject to the law of God, neither can it be” (Rom., viii. 7).
(b) If prudence of the flesh be taken in a less strict sense as signifying the behavior of those who make God the supreme end of their lives, but who in some affair plan shrewdly for a particular end that does not entirely square with right reason, it is then a venial sin. An example is a host who is very practical in buying supplies and making all the arrangements for a banquet at which the guests will conduct themselves with too much hilarity.
(c) If prudence of the flesh be used in a wide or improper sense as signifying the care of the body and other temporal things for the sake of a good end, it is not sinful, but virtuous. Thus, a person who is careful about his diet in order that he may conserve his health and be enabled to work more efficiently and fruitfully, is virtuously prudent. The use of the term “prudence of the flesh,” for these last two cases is inaccurate and misleading.