When St. Thomas works his way through the various sins of lust in ST II-II Q154, he gives a natural ethics reason to think that each is evil. His reason for the evil of simple fornication has always struck me as odd. Interesting and thought-provoking odd, not odd as a euphemism for wrong.
He’s obviously working from a theological tradition where the teaching about the evil of simple fornication could not be clearer: Jesus has some fairly terrifying things to say about sexual ethics and St. Paul puts fornication in every one of his lists of sins that bar entry to the kingdom of heaven.
Never one to leave a question at “Deus dixit”–the next word out of his mouth always being “Cur?” or maybe “Quomodo?”–Aquinas gives his natural ethics reason for the evil of simple fornication:
“…every sin committed directly against human life is a mortal sin. Now simple fornication implies an inordinateness that tends to injure the life of the offspring to be born of this union.” (Q154 a2 resp)
I find this position almost endlessly fascinating. The most basic reason for any action to be evil is that it is not in accord with reason. This reason principle shows up in a variety of ways; here Aquinas is linking it to a harm principle. But look who is being harmed!
Is “potential offspring” the way to say this? Here’s the Latin of “tends to…”
“vergit in nocumentum vitae eius qui est ex tali concubitu nasciturus.”
To hash up the Egnlish a little, an inordinateness that “verges into harm of the life of him/her who is to be born of such sleeping together.” I’m not familiar with the state of text criticism of Aquinas, but nocumentum is a really weird form. It should mean “little harm” or “nuisance,” but Aquinas can’t possibly mean that here (not if this is a mortal sin).
This may be where my aversion to secondary sources gets me in trouble, but I would guess he’s picked the form (instead of the straightforward noxam or even just malum) to show that we are dealing with a hypothetical or future harm.
But it’s a special kind of hypothetical harm, because we’re not talking about risk management. As the rest of the respondeo goes on to argue, if offspring arise they will be harmed. Not might, will. Being born of a determinate, fixed union is a good and to willfully deprive a child of that environment is evil.
Students always reply with things like “What if no child is conceived?” or “What about birth control?” If the argument is still to go through, it has to depend on a hypothetical indifference to the child’s life: if a child is born it will be harmed, but I choose to do it anyway. A depraved indifference argument, essentially.
Where this leaves the argument in the case of the truly sterile, I don’t know for sure. It’s at least a rare enough case that it doesn’t have a lot of practical bite to it. Unless we become a civilization that starts sterilizing ourselves to have sex whenever we want and, to be perfectly honest, that would not shock me at this point in our history.
I am not sure there is a direct comparison to any other aspect of ethics without getting into weird thought experiment type stuff. The closest analogy I can come up with is the ethics of reckless or drunk driving. Reckless driving is evil because it is grave indifference to the lives of the other drivers on the road you might encounter. But that’s got more risk and uncertainty to it: a reckless or impaired driver may well cross paths with other drivers and not harm them. Aquinas is claiming (I think) that any offspring born will be harmed ipso facto.
Now the similarities are still strong: a drunk driver might argue that he lives close by and no one will be out driving at this hour so in all likelihood there will be no one around to harm. So the same depraved indifference charge can be set back against him: if someone does happen to be out on the road I will be putting their life at grave risk, but I choose to do it anyway.
Does this “definite harm to a potential person” thinking show up anywhere else? I haven’t come up with one. More probable risks like the effects of smoking or drug use come close I suppose, but I think Aquinas is doing something other than risk management here.
I’ll be coming back to this with more organized thoughts (hopefully) in the future.