Just a quick thing: Those acts are unable to be open to the possibility of new life by nature and when everything is working as it is meant to. I’m adding that because someone is going to jump on and say it means infertile couples shouldn’t be able to get married.
Even in the case of the infertile couple, the sexual
acts of such a couple can still be open to the possibility of new life. Please allow me to explain myself here.
Because we are talking about the morality of a particular sexual act, we don’t need to consider factors that are
unrelated to the sexual act (which includes factors such as the reproductive health of the couple, the time of the month, etc…). Factors that exist regardless of whether or not a given couple were planning to have sex are unrelated to a particular sexual act and therefore do not influence the morality of the said act.
Think of it like having a series of doors in a hallway. Each door has a name on it, the doors can be either opened or closed, and if you can get to the end of the hallway then a new baby will be created. The doors have the following names:
- Sexual Act? (opened/closed)
- Reproductive Health? (opened/closed)
- Already Pregnant? (opened/closed)
- Time of the month?
- Pre Menopause?
- Etc…
New life is created
For a sexual act to be moral, door #1 must always be open no matter what. That’s all the Church says about the morality of a sexual act. Door #2 to 6 can all be closed and the sexual act can still be valid because the act itself is not closed to the possibility of new life.
In the case of homosexual sodomy, however, door 2-6 can all be open but door 1 will always be closed no matter what. I believe that is the fundamental difference between sodomy and natural infertility.
I hope that made at least a bit of sense.
