The defense you’re looking for seems to be one of consequentialism - what good comes of this, what harm comes of that? Catholicism is often deontological. The means are what is desired, not necessarily the outcome. We often judge objective good by how one lives rather than what one achieves. Where Catholicism is consequentialist - concerned with causing good or bad outcomes - you may not agree with what we see as harm.
Firstly the idea that sexual activity ought to always be ‘open to life’ is frankly ridiculous.
You correctly identify that Catholicism holds that sexual activity is intended for procreation and unity. If these are its intended uses, we can justifiably oppose others as being unnatural - abuse, control, manipulation, lust, selfish pleasuring, prostitution. If procreation is not a purpose of sexuality, then what is?
Contraception seems to be harmless and in good sense if one does not want to cause overpopulation.
We believe contraception to be harmful by showing disdain for the Creator’s intended purpose, and for offending God by disregarding what He has taught us. If you don’t believe in God, or don’t care about offending Him, or don’t think He’d find offense, or don’t think He’s intended sex to be for procreation, then contraception seems harmless.
If overpopulation is an evil that we wish to prevent, we should require a 100% guarantee of no procreation - namely abstinence (which has been shown to fail only once). Certainly we as human beings are capable of abstaining from sexual activity, and given the choice between short-term pleasure (if sex is neither intended for procreation nor for love) and long-term devastation, rationally we should be willing to give up pleasure.
But what is the real possibility of overpopulation compared against the real danger of depravity and sexual perversion?
‘The natural end of the genitals is procreation’ so what? Why shouldn’t I act against a natural end, where is the harm? Where is the loss of good?
The “loss of good” is the loss of the person’s soul - Rev. 21:8. If you don’t believe in the Bible, consider at least the loss of the person’s innocence, the change in the person’s disposition towards the opposite sex, and the emotional baggage that comes with it. Consider also the damage that occurs to the person’s partners.
Why should I respect every basic good in every act?
If you aren’t respecting good, what are you respecting?
But for me it is hard to accept that objectively a physical act is somehow and act of love as if the two are somehow bound – tied together in the very laws of the universe.
Before I saw my error and gave up sex at 22 (and waited until I was 27 and married to have sex again), I noticed that sex works to form a bond between people. Objectively it is a physical act in the same way that objectively tears rid the body of saline fluids and a hug shares body warmth. But we are not objective creatures. Subjectively, tears indicate strong emotion and the sight of a person crying often moves us to embrace them. Hugging a crying person makes no physical sense - they aren’t signaling the need for warmth, just a ridding of excess fluids, right?
Subjectively, sex is a promise, a connection, a bridge, unless we defeat that emotional mechanism. But why fight our emotions for the sake of pleasure? If pleasure is that worth it, why bother finding someone else whose emotions might get in the way?
How can a purely physical act objectively cause an emotion? Cannot actors kiss one another without feeling love? Then why cannot actors engage in intercourse without feeling love?
You don’t exactly sound like a considerate lover here. How can a purely physical act cause emotion? Because we’re emotional beings and we live subjectively first and objectively second. Our emotions are wired to our bodies, otherwise, why does one get more of an emotional high out of kissing than out of just being around a person?
Are you an objective being who views your experience through a detached lens, or are you subjective being aware of what you are thinking, feeling and looking for? Actors can kiss one another without feeling love, as can drunken revilers make out at Mardi Gras without feeling anything other than a buzz. As for intercourse, what sort of movies are you watching where the love scenes aren’t acted out? Besides, that’s acting, and this is real life. If you were to have sex with someone and say “Sorry, baby, I’m only acting”, what do you think the response would be?
Perhaps subjectively most of the time this is not possible, but it does not follow that it is never possible.
Normally, humans need to breathe to survive, but it does not follow that it is never possible for a human to survive for a time without breathing. Why suffocate yourself though? Likewise, why deprive your life of your emotions? Is sex worth that much to you?
Has no one noticed that virtually no respectable secular contemporary philosophers maintain a Catholic view of sexual morality? Surely this cannot purely because they have ‘hardened their hearts’
Apparantly you’ve noticed, but what are these respectable secular contemporary philosophers attempting to prove? What is their ultimate good to advance?
The Catholic Church advances Catholic faith and morality. If one wishes to advance individualism, liberalism, utilitarianism, utopianism, “free love”, or positive rationalism, one will not conclude sexual moraes on par with the Catholic Church.
Have you noticed, though, that Catholic sexual morality does not allow one to do as they might wish, but instead requires them to do as they should?