That an act may be “direct” (and immoral) or “indirect” (and moral) is not in debate. The act might be one that we know will abort a child, or one we know will sterilise marital relations, or similar. This is not the point in question.
The issue is whether in a particular case - viz: contraception so as not to have a Zika baby - the “contraception” is direct or indirect. I believe it is emphatically direct. The contraceptive effect is not a side-effect (in the consequences) it is the means - such an act, for achievement of its good intention, relies on eliminating the procreative meaning from a marital act.
Back in March 2016, you described the act in question as: “marital sex avoiding a seriously deformed baby” … and nominated its moral object as “paying the marital debt (unitive purpose) and wisely waiting for a better time to conceive a normal baby”.
[Post #192 in:
https://forums.catholic-questions.org/showthread.php?t=998309&highlight=Condoms+Zika]
My response was to point out the fatal flaw in this as follows:
*The act you describe as "marital sex avoiding a seriously deformed baby” does not expose the means adopted to serve the good intention – it is silent on how one avoids a deformed baby. It is far from a “concrete act” (see Veritatis Splendor) – we have no idea what concrete act is proposed, how therefore is it to be judged? You have left out an essential element of the act, and folded in the Intention. There are a number of options which would make the act (which you describe) concrete and thus allow moral assessment, eg: NFP, abstinence, Contraception and hopefully in due course - take a medication/vaccine. By not exposing the means, we cannot properly identify the object. The act (you propose or have in mind, but have not written down) is in fact concrete because a means (“contraception”) has been chosen - and thus the act is properly described as “contracepted marital sex”. When such is knowingly chosen, the moral object is the deprivation of the procreative aspect, a moral evil.
Depriving marital relations of the procreative aspect (as end or means) is moral evil. In your act, this is in the means. It is only when the deprivation is solely in the Consequences that we can say the contraception is “indirect”. *
Another poster commented similarly at the time:
*The use of contraception in cases of rape is not intrinsically evil because the object of the act is the moral interruption of the rape. The deprivation of the procreative meaning is only in the consequences, not in the object. That is an example of what might be called indirect contraception (similar to indirect sterilization or indirect abortion).
However, what makes it indirect is
not the intended end, but the moral species and moral object of the intentionally chosen act. *