Day 236: The Morality of Human Acts

It is therefore an error to judge the morality of human acts by considering only the intention that inspires them or the circumstances (environment, social pressure, duress or emergency, etc.) which supply their context. There are acts which, in and of themselves, independently of circumstances and intentions, are always gravely illicit by reason of their object; such as blasphemy and perjury, murder and adultery. One may not do evil so that good may result from it. CCC 1756

The Catechism discusses the morality of human acts in today's reading. Since human acts are freely chosen, they "can be morally evaluated" and thus "good or evil" (CCC 1749). Too often in modern society, whether something is "good or evil" is stripped down to ideology, preference, or utility. Objective truth and morality are discounted. Whether an act is morally good depends upon "the object itself;  the end in view or the intention; [and] the circumstances of the action" (CCC 1750). All of those must be morally good for the act itself to be morally good. 

I like how the Catechism Companion, Vol II, puts it:

For example, for a book to be good, it needs good writing, well-developed characters, and a good plot. If one of those is missing, it falls short and is not good. (p. 236)

The upshot is that "the end does not justify the means" (CCC 1753) and "one may not do evil so that good may result from it" (CCC 1756). The expression that "the road to hell is paved with the best of intentions" expresses this too, because a bad intention can make an act morally evil.