In Catholic teaching, the morality of human acts is determined by three fonts (from the Latin word for sources). An act is a deliberate knowing choice; it is an exercise of free will and reason. Each human act is moral or immoral; there are no knowingly chosen acts which are morally-neutral. An act is either a sin (immoral) or it is at least morally permissible (not a sin). Some moral acts are imperfect, but still permissible. Every sin is to be avoided. Sin is never justifiable.
The three fonts that determine the morality of an act are:
1. Intention — the intended end or goal of the act; this intention motivates the choice of the act. It is always a sin to act with a bad intention.
2. Object — the end, in terms of morality, toward which the knowingly chosen act is inherently ordered. When this end or object is bad, the deliberate knowing choice of the act ordered toward that end is always a sin. An act with an evil object is termed “intrinsically evil” because the act itself is ordered toward evil.
3. Circumstances — the totality of the foreseeable consequences of that act for all persons concerned. When the reasonably anticipated bad consequences morally outweigh the reasonably anticipated good consequences, then the choice of that act is always a sin (unless the circumstances change). It is always a sin to act when you realize your act will do more harm than good.
Each font proceeds from the human will toward a type of end: the intended end, the moral object, and the end results (consequences). Each end is judged, as to its morality, by comparing that end to the love of God and the love of neighbor as self. Ends which are incompatible with that three-fold love are bad, making the font bad and the act a sin.
An act is a sin if it has one, two, or three bad fonts. An act is morally-permissible only if it has three good fonts.
Any evil in any font makes that font bad, regardless of other goods in the same or other fonts. So, if there is one bad intention and two good intentions, all in the same act, that act is a sin, due to the one bad intention. The good intentions cannot be used to justify the bad intention, even if those goods are proportionately greater.
If there are two good objects and one bad object in the same act, then that act is intrinsically evil, due to the one bad object. The presence of two good objects cannot justify the bad object because any evil in the object makes the act intrinsically evil. There is no proportionality in the first or second fonts.
However, the font of circumstances admits proportionality. The good and bad consequences are weighed against one another, and if the bad does not outweigh the good, the font is morally permissible.
We are made in the image of God, and we are called to avoid anything contrary to that love. All sin is contrary to love in some way, to some extent. We should only choose acts which are good in every possible way.
If an act is not intrinsically evil, then its morality depends on intention and circumstances. But you should not be too quick to determine that an act is not intrinsically evil. Not every intrinsically evil act is commonly condemned as such by the Church. The Magisterium cannot list every possible sin. Instead, the Magisterium teaches the basic principles of ethics, and the faithful are to apply those teachings to their lives.
See my book: Roman Catholic Teaching on Intrinsic Evil
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