Edward Feser's argument for the immorality of sex (that doesn't result in reproduction)

[Angra Mainyu]

Just a clarification point: I'm replying to the argument as presented in this thread. I know that some theologians make a more sophisticated argument - probably Feser too -, addressing some of my points.
Those arguments fail as well, but the reply would have to be modified to some extent (e.g., different examples, limiting the number of objections), and be tailored to each variant.
But if you bring a specific variant of the argument, I'll debunk it.

Thanks, Angra, your response was very helpful. So far as I know, Feser has not given this more context, but I don't always read his blog so I'm not sure. But thanks again.

You're welcome.
A common argument by so-called "natural law" Thomists (a problem with the name is that it's a specific type of theory; one may as well subscribe to a theory that holds that there is a natural law, but it's not like that proposed by Thomists) is that somehow gay sex - or some other form of non-reproductive sex, depending on the case - frustrates the purpose of sex - which is reproduction, or reproduction + unity between man and woman, or something like that -, whereas using blinking to communicate is a use that, while not part of the purpose of blinking, it does not frustrate it - since blinking is still spreading tears, etc.
They would also say that - for example - using earplugs blocks or reduces the hearing function, but it does not use it for a purpose that is deviant, or perverse.
An example of that is Timothy Hsiao's paper "Why Homosexual Sex is Immoral".
Part of the reply to that is to reject the claim that sex, or sexual organs, etc., have purposes, even if they have biological functions.
But that aside, there are a number of ways you could reply.
One is the "one person's modus ponens is another person's modus tollens" way: given that it's obviously not the case that gay sex (or masturbation, oral sex, etc.) is always or generally immoral, then the so-called "natural law" theory is false.
Another reply is to consider chewing sugar-free gum. That would allegedly be just as "perverse" if this "natural law" theory were correct, since that would engage our masticatory faculty but in a way that is intrinsically not nutritious, while the biological function of that faculty is to begin digestion.
If the Thomist says that even sugar-free gums have a few calories, that would only expose the Thomistic moral theory as even more clearly ridiculous, since it's obviously not the case that chewing gum would become immoral if those very few calories are removed. Additionally, one might use the examples of chewing on something else with no calories, like a (unused!) chew toy for dogs. That would be odd, but not immoral (e.g., maybe someone does it just to make a point about Thomism ).
If the Thomist replies that chewing also has a function not related to nourishment, then one may say there is no particular reason why that's not so of sex and sexual organs. For example, sex may have the function of reducing stress and/or giving pleasure and/or enhance the bonds between two people, regardless of their sex or gender. The Thomist will reject that, but there is no particular reason to believe there is no such function of sex but there is such function of chewing - i.e., the Thomist would have no good reason for his belief.

 

[Keith&Co.]

"If we consider the structure of the sexual organs and the sexual act as a process beginning with arousal and ending in orgasm, it is clear that its biological function, its final cause, is to get semen into the vagina. That is why the penis and vagina are shaped the way they are, why the vagina secretes lubrication during sexual arousal, and so forth … The point of the process is not just to get semen out of the male, but also into the female, and into one place in the female in particular. [144]
It cannot possibly be good for us to use them in any other way, whether an individual person thinks it is or not. ".

Once upon a time, i was performing a technical operation while being observed. I had a socket on an extension connected to a ratchet handle and started to loosen a bolt. After a few turns, the bolt was stil lthreaded through the mounting plate, but it was loose enough that it did not resist the ratchet. So the bolt turned whether i turned the ratchet handle clockwise or counterclockwise. So i reached down with my free hand and turned the socket itself. It came out, the shaft spun freely and i failed the operation.

The observer told me that i had "defeated the purpose of the ratchet." I'd never been taught that this was a thing. So i reported it to my chief, who called it bullshit. Weps confronted the inspector and demanded evidence that there was a 'purpose of the ratchet' that could be defeated by still using the tool to remove the bolt. He could use any reference at alll, either from the designer of the ratchet, or the designers of the bolt that was being removed, or a tool-handling reference or anything but his flapping yap.
He hemmed and hawed and finally shut up, removing the hit from the overal inspection report.

It's possible that non-procreative sex defeats the purpose of the reproductive system. I'd have to see the owner's manual or the designer's spec sheet to be sure, though. It's quite possible that either God designed multiple uses for the act (kids, bonding, intimacy, commerce) that were not made expressly clear, or that there's no designer.

 

[PyramidHead]

Hey. As I've been continuing my studies on medieval scholastic, Aristotle's principles and so forth, I saw this argument written by Edward Feser:

"If we consider the structure of the sexual organs and the sexual act as a process beginning with arousal and ending in orgasm, it is clear that its biological function, its final cause, is to get semen into the vagina. That is why the penis and vagina are shaped the way they are, why the vagina secretes lubrication during sexual arousal, and so forth … The point of the process is not just to get semen out of the male, but also into the female, and into one place in the female in particular. [144]


It cannot possibly be good for us to use them in any other way, whether an individual person thinks it is or not. "

I wanted to see your opinions on it. Feser's God is obviously the God from classical theism, and defined in terms of pure actuality. I don't think this thread is suited for a discussion on Thomism, though, so if I may ask, keep the discussion on the logical structure of the argument.

My opinion is that this argument is not valid, which means the conclusion does not follow from the premises, but if we add that it was a morally perfect being who created us with our nature, then things might get different.

Feser appears to completely ignore the consequences of sexual reproduction when compared to sex without the possibility of reproduction.

In the first case, a new human being is created, and resources that could have otherwise been used for existing humans must be diverted to sustain this new person. In addition, the new person will experience a non-trivial amount of pain during his/her life. Both the diversion of resources and the pain of the new person are negative outcomes that would not occur in the case of sex without the possibility of reproduction.

The obvious implication, that runs counter to Feser's assumption (and possibly yours, as evidenced by your argument for homosexuality as a pathology), is that nature does not have our best interests in mind. We can't just assume that the ordinary functioning of any natural system will result in the most optimal conditions for our happiness and well-being. In fact, the opposite is true: from the get-go, we are born as a terminal, rapidly decaying body that must be immediately and continually rescued from death by a considerable amount of effort, both from ourselves and our community. Nature has not set up a perfect or even a desirable set of conditions for us--only a sufficient set of conditions to propagate our genes. Start with a basic self-replicating organism, add a dash of sexual appetite, a pinch of mortal fear, a sprig of Pollyanna to keep everything rolling along, and the species perpetuates itself. When faced with a pair of options, natural selection will always favor the one that uses less energy while achieving functionally the same result. There is no reason to believe these selection criteria will give rise to a biology that is emotionally or morally satisfying.

It follows that no argument about how things ought to be can be predicated on a description of how they currently are. But you already knew that if you've studied Hume.

 

[bilby]

"If we consider the structure of the sexual organs and the sexual act as a process beginning with arousal and ending in orgasm, it is clear that its biological function, its final cause, is to get semen into the vagina. That is why the penis and vagina are shaped the way they are, why the vagina secretes lubrication during sexual arousal, and so forth … The point of the process is not just to get semen out of the male, but also into the female, and into one place in the female in particular. [144]
It cannot possibly be good for us to use them in any other way, whether an individual person thinks it is or not. ".

Once upon a time, i was performing a technical operation while being observed. I had a socket on an extension connected to a ratchet handle and started to loosen a bolt. After a few turns, the bolt was stil lthreaded through the mounting plate, but it was loose enough that it did not resist the ratchet. So the bolt turned whether i turned the ratchet handle clockwise or counterclockwise. So i reached down with my free hand and turned the socket itself. It came out, the shaft spun freely and i failed the operation.

The observer told me that i had "defeated the purpose of the ratchet." I'd never been taught that this was a thing. So i reported it to my chief, who called it bullshit. Weps confronted the inspector and demanded evidence that there was a 'purpose of the ratchet' that could be defeated by still using the tool to remove the bolt. He could use any reference at alll, either from the designer of the ratchet, or the designers of the bolt that was being removed, or a tool-handling reference or anything but his flapping yap.
He hemmed and hawed and finally shut up, removing the hit from the overal inspection report.

Sounds to me like he just liked to hear himself torque.

 

[Bronzeage]

Once upon a time, i was performing a technical operation while being observed. I had a socket on an extension connected to a ratchet handle and started to loosen a bolt. After a few turns, the bolt was stil lthreaded through the mounting plate, but it was loose enough that it did not resist the ratchet. So the bolt turned whether i turned the ratchet handle clockwise or counterclockwise. So i reached down with my free hand and turned the socket itself. It came out, the shaft spun freely and i failed the operation.

The observer told me that i had "defeated the purpose of the ratchet." I'd never been taught that this was a thing. So i reported it to my chief, who called it bullshit. Weps confronted the inspector and demanded evidence that there was a 'purpose of the ratchet' that could be defeated by still using the tool to remove the bolt. He could use any reference at alll, either from the designer of the ratchet, or the designers of the bolt that was being removed, or a tool-handling reference or anything but his flapping yap.
He hemmed and hawed and finally shut up, removing the hit from the overal inspection report.

Sounds to me like he just liked to hear himself torque.

The purpose of a ratchet is to make the work easier and faster. Anyone who would call that "defeating the purpose of a ratchet" reveals they have not used a ratchet very much and shouldn't be in a position to judge anyone else's performance.

 

[Angry Floof]

I used a ratchet in lieu of a hammer once.

I'm going straight to hell.

 

[Bronzeage]

I used a ratchet in lieu of a hammer once.

I'm going straight to hell.

That does not exactly defeat the purpose of a ratchet, but it's still a bad thing to do. Eventually, that ratchet will have no purpose.

 

[Dekusta]

Hey. As I've been continuing my studies on medieval scholastic, Aristotle's principles and so forth, I saw this argument written by Edward Feser:

"If we consider the structure of the sexual organs and the sexual act as a process beginning with arousal and ending in orgasm, it is clear that its biological function, its final cause, is to get semen into the vagina. That is why the penis and vagina are shaped the way they are, why the vagina secretes lubrication during sexual arousal, and so forth … The point of the process is not just to get semen out of the male, but also into the female, and into one place in the female in particular. [144]


It cannot possibly be good for us to use them in any other way, whether an individual person thinks it is or not. "

I wanted to see your opinions on it. Feser's God is obviously the God from classical theism, and defined in terms of pure actuality. I don't think this thread is suited for a discussion on Thomism, though, so if I may ask, keep the discussion on the logical structure of the argument.

My opinion is that this argument is not valid, which means the conclusion does not follow from the premises, but if we add that it was a morally perfect being who created us with our nature, then things might get different.

Feser appears to completely ignore the consequences of sexual reproduction when compared to sex without the possibility of reproduction.

In the first case, a new human being is created, and resources that could have otherwise been used for existing humans must be diverted to sustain this new person. In addition, the new person will experience a non-trivial amount of pain during his/her life. Both the diversion of resources and the pain of the new person are negative outcomes that would not occur in the case of sex without the possibility of reproduction.

The obvious implication, that runs counter to Feser's assumption (and possibly yours, as evidenced by your argument for homosexuality as a pathology), is that nature does not have our best interests in mind. We can't just assume that the ordinary functioning of any natural system will result in the most optimal conditions for our happiness and well-being. In fact, the opposite is true: from the get-go, we are born as a terminal, rapidly decaying body that must be immediately and continually rescued from death by a considerable amount of effort, both from ourselves and our community. Nature has not set up a perfect or even a desirable set of conditions for us--only a sufficient set of conditions to propagate our genes. Start with a basic self-replicating organism, add a dash of sexual appetite, a pinch of mortal fear, a sprig of Pollyanna to keep everything rolling along, and the species perpetuates itself. When faced with a pair of options, natural selection will always favor the one that uses less energy while achieving functionally the same result. There is no reason to believe these selection criteria will give rise to a biology that is emotionally or morally satisfying.

It follows that no argument about how things ought to be can be predicated on a description of how they currently are. But you already knew that if you've studied Hume.

I'm enjoying the responses so far, but one point about the other argument you mentioned: I made clear that I didn't think it would work. Aaand it didn't, as those who responded showed me why.

I also said on this one that I didn't think it followed anyway. But if it did then I could prepare my reservation in (the colder point) hell

It is interesting that babies have been proving Thomists wrong all this time, since they chew anything they see regardless of final causes. Aquinas? Final cause? Baby gave 2 shits.

 

[Dekusta]

One could reply that we cannot infer a clear function while looking at the act of blinking, that is the same way Feser analyzes the sexual organs (by observing sexual organs and the act of sex), but that would not work I guess.

 

[Keith&Co.]

One could reply that we cannot infer a clear function while looking at the act of blinking, that is the same way Feser analyzes the sexual organs (by observing sexual organs and the act of sex), but that would not work I guess.

I think that's come up in discussions about life before.
In a mechanical, designed device, you can clearly identify a function for each component. A detent is there for a reason, as is each spring or cam shaft. It's there for a function that the designer wanted, even if only cosmetic.

In biology, most things seem to have multiple functions. The eye blinks to moisten the eye and to clear contamination and seems to be crosswired to mental activity (you blink more when you're interested, though interest doesn't make the eyes drier or draw dust particles) for some reason.

Whether or not the human body is designed by a god, or just evolved, the process that produced the genitals would follow this aspect of biology. It would be consistent with the rest of the body if reproductive organs support the function of reproduction AND support non-reproductive functions such as bonding between partners or simple entertainment or a substrate upon which lies can be built to make your peers jealous.

So if someone's identified THE ONE AND ONLY true function of some part of human biology, wouldn't they need to provide a shitload of proof that this part is different from all the rest?

 

[Angra Mainyu]

One could reply that we cannot infer a clear function while looking at the act of blinking, that is the same way Feser analyzes the sexual organs (by observing sexual organs and the act of sex), but that would not work I guess.

By looking at the sexual organs and one specific act of sex (PIV), it's not immediately apparent that it's connected to reproduction, unless one has a lot of other info. But the same goes for blinking.

In any case, while the blinking example works against the argument as presented in this thread, Timothy Hsiao responds to examples like that on his paper against gay sex, so I came up with the chewing example to deal with his reply as well - and also with Feser's argument.

The chewing example has yet another advantage: the connection between chewing and eating is considerably more obvious than the connection between PIV sex and reproduction (obvious to whom? That's usually a question. But let's say it's easier for humans to figure that out), whereas the connection between chewing and nourishment is at least not less clear than between PIV sex and reproduction.

That said, of course one may say that chewing (and humans masticatory organs) has other functions. But similarly, one may say that in the case of sex (and human sexual organs), and there simply is no good reason to think Feser's claims that there are no other or no other stand-alone functions (or, for that matter, Hsiao's claims) are any more plausible than the corresponding claims in the case of chewing.

 

[bilby]

Intra-marital penis-in-vagina sex without the use of contraception results in pregnancy less often than it does not result in pregnancy. If the sole purpose of sex is procreation, this is not what we would expect to see at all.

The primary function of the penis is (obviously) to allow directed urination. Any man who uses his penis for any purpose other than urination is clearly going against God's will; All male urination should be directed so as to write verses from scripture in the snow (or dust, depending on climate and season), and to do otherwise is an abomination.

This is so obvious that I really shouldn't need to point it out. You all know it, and that you don't act upon it just demonstrates what a miserable bunch of sinners you all are.

 

[Dekusta]

One could reply that we cannot infer a clear function while looking at the act of blinking, that is the same way Feser analyzes the sexual organs (by observing sexual organs and the act of sex), but that would not work I guess.

By looking at the sexual organs and one specific act of sex (PIV), it's not immediately apparent that it's connected to reproduction, unless one has a lot of other info. But the same goes for blinking.

In any case, while the blinking example works against the argument as presented in this thread, Timothy Hsiao responds to examples like that on his paper against gay sex, so I came up with the chewing example to deal with his reply as well - and also with Feser's argument.

The chewing example has yet another advantage: the connection between chewing and eating is considerably more obvious than the connection between PIV sex and reproduction (obvious to whom? That's usually a question. But let's say it's easier for humans to figure that out), whereas the connection between chewing and nourishment is at least not less clear than between PIV sex and reproduction.

That said, of course one may say that chewing (and humans masticatory organs) has other functions. But similarly, one may say that in the case of sex (and human sexual organs), and there simply is no good reason to think Feser's claims that there are no other or no other stand-alone functions (or, for that matter, Hsiao's claims) are any more plausible than the corresponding claims in the case of chewing.

But if we assume the purpose of chewing is to "begin digestion", if I chew a gun or something else am I not beginning the digestion of those things? If the "thing" we're talking about is something that cannot be digested, than that would work more properly, or if the chewing function is pointed out as more related to nutrition, i.e. if it has the purpose related to nutrition in some other way, say "the purpose of chewing is to prepare the nutrishing food to be digested". Another way around the chewing example I can think of is to say that it's purpose is to make the process easier by slicing the food into pieces, but that also faces problems if the "thing" being chewed cannot be sliced or is already little. These are my thoughts, anyway.

 

[Angra Mainyu]

But if we assume the purpose of chewing is to "begin digestion", if I chew a gun or something else am I not beginning the digestion of those things?

Not if those things can't be digested. But I'm talking about the digestion of food (i.e., something that is nutritious).

If the "thing" we're talking about is something that cannot be digested, than that would work more properly, or if the chewing function is pointed out as more related to nutrition, i.e. if it has the purpose related to nutrition in some other way, say "the purpose of chewing is to prepare the nutrishing food to be digested".

I don't accept that biological systems or processes have any purpose other than what we give them, so I would talk about bioloogical functions, but that aside, by "begin digestion", I'm talking about digestion of things that can provide some nutrition.
That is why I said the problem would be (making a parallel to gay sex being "intrinsically" not reproductive) "intrinsically not nutritious", and also why I pointed out that saying that even sugar-free gum has a very low number of calories (so, there is a little bit of nutrition in there) would not help the Thomist

But if you think the way I put it is not clear and prefer to say the function is to prepare food (i.e., something that provides some nutrition) to be digested, okay that works too (but keep in mind that enzymes in the saliva begin to digest food before it gets to the stomach), no problem.

Another way around the chewing example I can think of is to say that it's purpose is to make the process easier by slicing the food into pieces, but that also faces problems if the "thing" being chewed cannot be sliced or is already little. These are my thoughts, anyway.

What do you mean "around the chewing example"?
Are you talking about a way for a Thomist to avoid it?

 

[Dekusta]

Not if those things can't be digested. But I'm talking about the digestion of food (i.e., something that is nutritious).

If the "thing" we're talking about is something that cannot be digested, than that would work more properly, or if the chewing function is pointed out as more related to nutrition, i.e. if it has the purpose related to nutrition in some other way, say "the purpose of chewing is to prepare the nutrishing food to be digested".

I don't accept that biological systems or processes have any purpose other than what we give them, so I would talk about bioloogical functions, but that aside, by "begin digestion", I'm talking about digestion of things that can provide some nutrition.
That is why I said the problem would be (making a parallel to gay sex being "intrinsically" not reproductive) "intrinsically not nutritious", and also why I pointed out that saying that even sugar-free gum has a very low number of calories (so, there is a little bit of nutrition in there) would not help the Thomist

But if you think the way I put it is not clear and prefer to say the function is to prepare food (i.e., something that provides some nutrition) to be digested, okay that works too (but keep in mind that enzymes in the saliva begin to digest food before it gets to the stomach), no problem.

Another way around the chewing example I can think of is to say that it's purpose is to make the process easier by slicing the food into pieces, but that also faces problems if the "thing" being chewed cannot be sliced or is already little. These are my thoughts, anyway.

What do you mean "around the chewing example"?
Are you talking about a way for a Thomist to avoid it?

Yes, that's what I meant by "Around the chewing example" but with your fruther explication I see no other way around it.

I was thinking of further perspectives on Feser's argument and this came to mind: if we look carefully at our "sexual system", we will see that men never stop producing sperm, women ovulate many times and we feel the need for sex frequently (or with relative frequency superior to one or two). So, by his lights, the final cause (or purpose) of sex would have to come attached with a "frequently", else we are cherry picking facts about sexual organs to justify our own positions. So even if a person has sex for reproduction this person would have to do it with the intention to reproduce many times over since that's the purpose of sex.

Another way I thought is that a guy, let's call him Erik, is sterile, and is aware of this moral theory and believes it to be true. So, Erik has no way to know that he is sterile (because of his lack of understanding of how the body works and the place he lives has no such support) so he keeps trying to reproduce and fails all the attempts. Erik lived an immoral and horrible life without even knowing it. I'm not sure how this cuts the argument, but I think it would be unfair if that was true.

 

[Bronzeage]

Intra-marital penis-in-vagina sex without the use of contraception results in pregnancy less often than it does not result in pregnancy. If the sole purpose of sex is procreation, this is not what we would expect to see at all.

The primary function of the penis is (obviously) to allow directed urination. Any man who uses his penis for any purpose other than urination is clearly going against God's will; All male urination should be directed so as to write verses from scripture in the snow (or dust, depending on climate and season), and to do otherwise is an abomination.

This is so obvious that I really shouldn't need to point it out. You all know it, and that you don't act upon it just demonstrates what a miserable bunch of sinners you all are.

Just a technical point, one which is pretty much lost on the modern world, but writing scripture with urine would be a sacrilege right out of The 120 Days of Sodom.

 

[Angra Mainyu]

I was thinking of further perspectives on Feser's argument and this came to mind: if we look carefully at our "sexual system", we will see that men never stop producing sperm, women ovulate many times and we feel the need for sex frequently (or with relative frequency superior to one or two). So, by his lights, the final cause (or purpose) of sex would have to come attached with a "frequently", else we are cherry picking facts about sexual organs to justify our own positions. So even if a person has sex for reproduction this person would have to do it with the intention to reproduce many times over since that's the purpose of sex.

But when they make more sophisticated arguments, they claim that there is no obligation to reproduce, but rather, that if chooses to use the sexual organs, one ought to do it without blocking their purpose (I'd say "biological function"), or doing it in a way that is intrinsically contrary to their biological function (in this case, intrinsically non-reproductive).

Another way I thought is that a guy, let's call him Erik, is sterile, and is aware of this moral theory and believes it to be true. So, Erik has no way to know that he is sterile (because of his lack of understanding of how the body works and the place he lives has no such support) so he keeps trying to reproduce and fails all the attempts. Erik lived an immoral and horrible life without even knowing it. I'm not sure how this cuts the argument, but I think it would be unfair if that was true.

They would say Erik did not do anything wrong, because even if defective, his sexual organs are still directed to reproduction. Hsiao actually make a point like that, in the paper I mentioned ( https://www.academia.edu/4575504/Why_Homosexual_Sex_is_Immoral ) (you have to register in order to download the paper, but it's free).

 

[Angry Floof]

Intra-marital penis-in-vagina sex without the use of contraception results in pregnancy less often than it does not result in pregnancy. If the sole purpose of sex is procreation, this is not what we would expect to see at all.

The primary function of the penis is (obviously) to allow directed urination. Any man who uses his penis for any purpose other than urination is clearly going against God's will; All male urination should be directed so as to write verses from scripture in the snow (or dust, depending on climate and season), and to do otherwise is an abomination.

This is so obvious that I really shouldn't need to point it out. You all know it, and that you don't act upon it just demonstrates what a miserable bunch of sinners you all are.

Just a technical point, one which is pretty much lost on the modern world, but writing scripture with urine would be a sacrilege right out of The 120 Days of Sodom.

Oh hell yeah. They were serious about that crap. If there was one tiny mistake on one skin, they'd throw it away and also toss the skin preceding it because it had touched the one with a mistake. That's dedication.

 

[Dekusta]

But when they make more sophisticated arguments, they claim that there is no obligation to reproduce, but rather, that if chooses to use the sexual organs, one ought to do it without blocking their purpose (I'd say "biological function"), or doing it in a way that is intrinsically contrary to their biological function (in this case, intrinsically non-reproductive).

Another way I thought is that a guy, let's call him Erik, is sterile, and is aware of this moral theory and believes it to be true. So, Erik has no way to know that he is sterile (because of his lack of understanding of how the body works and the place he lives has no such support) so he keeps trying to reproduce and fails all the attempts. Erik lived an immoral and horrible life without even knowing it. I'm not sure how this cuts the argument, but I think it would be unfair if that was true.

They would say Erik did not do anything wrong, because even if defective, his sexual organs are still directed to reproduction. Hsiao actually make a point like that, in the paper I mentioned ( https://www.academia.edu/4575504/Why_Homosexual_Sex_is_Immoral ) (you have to register in order to download the paper, but it's free).

Then there seems to be a moral problem here. If Erik doesn't know of his sterile condition, then that's fine, but what if he knows and still does it, say, in hope for a "miracle"? If that's the case, a gay couple (this will sound bizarre at least) that has sex and hopes for a miracle of being able to reproduce with their partner isn't being immoral at all, i.e. their sexual organs are still directed to reproduction.

And why would they think there is no obligation to reproduce? That would be to refuse to use your organs while they do have a purpose or final cause. The purpose is to reproduce not to " not be used" or even "be kept inside your pants the entre time". A person that refuses the purpose of her eyes to see (and chooses not to see) or refuses the purpose of their lungs and do not breathe (or find a way to stop breathing) or refuse the purpose of their legs and stop walking isn't helping the Thomist make his case.

 

[Angra Mainyu]

Then there seems to be a moral problem here. If Erik doesn't know of his sterile condition, then that's fine, but what if he knows and still does it, say, in hope for a "miracle"? If that's the case, a gay couple (this will sound bizarre at least) that has sex and hopes for a miracle of being able to reproduce with their partner isn't being immoral at all, i.e. their sexual organs are still directed to reproduction.

You would have to ask the people making those unwarranted moral claims and subscribing to the theory they call "natural law" to be sure.

But I reckon they might say that Erik does not need to hope for a miracle, since he does not need to be trying to reproduce - he just needs to use the organs in the way compatible (in some mysterious way) with their alleged "purpose" -, while the gay couple is being immoral because their organs are still being used in a way that goes against their "purpose" and they shouldn't expect help from God.

Alternatively or additionally, they might say that hoping for a miracle is not an excuse, just as shooting a random person hoping that God will deflect the bullet and guide it to a better target - like a terrorist, or whatever - is no excuse for shooting people.

Or maybe they'll come up with something else; I don't know. Maybe you could test that on someone who holds such views.

And why would they think there is no obligation to reproduce? That would be to refuse to use your organs while they do have a purpose or final cause. The purpose is to reproduce not to " not be used" or even "be kept inside your pants the entre time". A person that refuses the purpose of her eyes to see (and chooses not to see) or refuses the purpose of their lungs and do not breathe (or find a way to stop breathing) or refuse the purpose of their legs and stop walking isn't helping the Thomist make his case.

I think I wasn't precise enough here. They tend to think that there is an obligation to try to reproduce in many cases, but there is also not an obligation in many others. Some cases in which they think there is no such obligation are priests, nuns, women after menopause, generally sterile people, people who already have children, people who do not have the resources to raise children properly because they're in dire poverty, etc.

But I tend to agree with you that those examples are a problem for them too. Still, some would make a distinction between not engaging a function, and using it in a deviant or perverted manner, which allegedly negates their alleged purpose. On this account, not using your eyes is not deviant use, but having gay sex is. I don't think this distinction is justified (i.e., morally, it's not relevant), but they do make it (for more info, I suggest you read the paper I linked to, and/or another one of Hsiao's papers on the matter of gay sex). The chewing example is meant to work around that distincion - because by the way they seem to distinguish behaviors, it would count as perverted use.