Most persons know the answer to this question: Good intentions are necessary, but not sufficient, to make an act moral.
However, many false teachers have risen up, using clever arguments, the result of which is to justify any act — including contraception, abortion, and all manner of grave sexual sins — merely by good intentions.
The Magisterium teaches that, to be moral, an act must have three good fonts of morality:
1. only good intentions
The intention is the purpose or intended end for which the act was chosen.
2. only good in the moral object
The moral object is the end, in terms of morality, toward which the deliberately chosen act is intrinsically directed.
3. the good consequences must equal or outweigh the bad consequences
The reasonably anticipated good and bad consequences must be evaluated for all persons affected by the chosen act.
If any one font is bad, then the act is a sin; it is immoral. Only if all three fonts are good is an act moral.
Good intentions are necessary, so that the first font of morality will be good. But intention is only in the first font. Each font of morality is independent of the other two. When one font is bad, nothing in the other two fonts can justify that act. It is always as sin, as long as any one or more fonts remains morally disordered.
Various clever false arguments are being used by various false teachers, along with the claim that their grave errors are really the teaching of the Church, which in effect actually nullify the teaching of the Church on ethics.
First, they claim that an intrinsically evil act, such as contraception or abortion or an unnatural sexual act, becomes moral by being used with a good intention, i.e. for a good purpose. This claim implies that a change in intention can transform an act from intrinsically evil into a good and moral act. This claim is directly contrary to the teaching of the Magisterium.
Pope John Paul II: “If acts are intrinsically evil, a good intention or particular circumstances can diminish their evil, but they cannot remove it. They remain ‘irremediably’ evil acts; per se and in themselves they are not capable of being ordered to God and to the good of the person…. Consequently, circumstances or intentions can never transform an act intrinsically evil by virtue of its object into an act ‘subjectively’ good or defensible as a choice.” (Veritatis Splendor, n. 81).
If a married couple use abortifacient contraception for a medical purpose, they are using an intrinsically evil means to a good end. The Church teaches that the end does not justify the means. But these false teachers claim that the good purpose (the intended end) makes the act no longer intrinsically evil.
If a couple use abortifacient contraception for a medical purpose, they claim that the deaths of the prenatal children resulting from this deliberate choice of the couple are ‘indirect’ and therefore moral. Nothing could be further from the teaching of the Church. The purpose for which the act is chosen is the font called intention. This font has no effect on the font called moral object. The use of abortifacient contraception is intrinsically evil and always gravely immoral because it is the type of act that is “irremediably evil”, in and of itself. Neither intention or circumstances can make such an act moral. Therefore, abortifacient contraception does not become moral by being used for a good purpose, such as to treat a medical disorder.
On the question of the circumstances, they claim that if any bad consequences of an act are unintended, then those consequences do not affect the morality of the act. Again, nothing could be further from the teaching of the Magisterium. Intention and circumstances are two different fonts of morality. Each is evaluated on its own merits. It would be immoral if the bad consequences were the intended end of the act; if so, then the first font of intention is bad. But it would also be immoral if the unintended bad consequences outweigh the good consequences; if so, then the third font of circumstances is bad.
They also claim that the principle of double effect justifies various intrinsically evil acts. And that the principle of double effect nullifies all bad effects, if they are unintended. These claims are directly contrary to what the principle of double effect actually says. See this source.
Notice the result of the above-discussed false teaching: the morality of any act seems to be based solely on intention. An intrinsically evil act is claimed to be no longer intrinsically evil, if it is used for a good purpose (i.e. a good intended end). Sometimes they actually state that the good intention makes the act no longer intrinsically evil. And all of the bad effects of the act are said to have no moral weight, if these are unintended. So by appeal to good intentions in the first font of morality, they nullify the other two fonts. This allows them to claim that any act at all is moral, as long as the person committing the act has a good intention.
This false teaching is in danger of prevailing over the truth in the minds and hearts of a majority of the faithful.
Here is what the Magisterium teaches on the three fonts of morality:
Catechism of the Catholic Church: “The morality of human acts depends on: — the object chosen; — the end in view or the intention; — the circumstances of the action. The object, the intention, and the circumstances make up the ‘sources,’ or constitutive elements, of the morality of human acts.”
Compendium of the Catechism: “The morality of human acts depends on three sources: the object chosen, either a true or apparent good; the intention of the subject who acts, that is, the purpose for which the subject performs the act; and the circumstances of the act, which include its consequences.”
USCCB Catechism: “Every moral act consists of three elements: the objective act (what we do), the subjective goal or intention (why we do the act), and the concrete situation or circumstances in which we perform the act…. All three aspects must be good — the objective act, the subjective intention, and the circumstances — in order to have a morally good act.”