A person is capable of distinguishing good actions from bad ones because he possesses reason and a conscience, which enable him to make clear judgments.
The following guidelines make it easier to distinguish good actions from bad ones:
(1) What I do must be good; a good intention alone is not enough. Bank robbery is always bad, even if I commit that crime with the good intention of giving the money to poor people.
(2) Even when what I do is truly good, if I perform the good action with a bad intention, it makes the whole action bad. If I walk an elderly woman home and help her around the house, that is good. But if I do it while planning a later break-in, that makes the whole action something bad.
(3) The circumstances in which someone acts can diminish his responsibility, but they cannot change at all the good or bad character of an action. Hitting one’s mother is always bad, even if the mother has previously shown little love to the child.
May we do something bad so that good can result from it?
No, we may never deliberately do something evil or tolerate an evil so that good can result from it. Sometimes there is no other course of action but to tolerate a lesser evil in order to prevent a greater evil.
The end does not justify the means. It cannot be right to commit infidelity so as to stabilize one’s marriage. It is just as wrong to use embryos for stem cell research, even if one could thereby make medical breakthroughs. It is wrong to try to “help” a rape victim by aborting her child.
Dig Deeper: Catholic Catechism section (1749-1761) and other references @ http://www.catholiccrossreference.com/catechism/#!/search/1749-1761
My Source: I got this in a daily email I get about Catholic teachings. Okay, not the cat. That I added myself. 🙂