Those people are bigots, and no amount of logic will comvince them to change their minds, until they realize that their bigoted position hurts trans people (and decide that hurting trans people is a bad thing).
What do you mean, “how”? They identify as a man, and they want a child. They either don’t have as big a hangup as you do about the idea of being pregnant and male, or they DO have that hangup but want a child badly enough to deal with it. How is it any of your business?
You probably wouldn’t, but rapists rarely take the victims desires into account. So unless you scrupulously took your birth control shots/implant/IUD/pills, you could end up pregnant. Hell, even doing everything correctly, there is still a slight possibility of ending up pregnant. [Hell, I had an old school loop and band ligation, ended up with one side popping the scar plug and ended up pregnant 10 years after the tubal … oops.]
But then again, you might opt to bear a single child to carry on your genetic heritage before getting organs rearranged. Who can say, the desire for a child can be incredibly strong in both men and women.
But, unless your shoes are under my bed, I really have no say in the matter, other than to treat you with civility. That means calling you by your chosen name, pronouns and so forth.
Moderating:
Please comment on the content, not the contributor. Whether or not ultravires has “hangups” is not helpful in addressing the question.
You could, for instance, have said:
They identify as a man, and they want a child. They either don’t have a hangup about the idea of being pregnant and male, or they DO have that hangup but want a child badly enough to deal with it.
Male and female is biology. Man and woman is sociology. I have a female dog. I do not have a woman dog.
But man/woman can also mean an adult male/female. Boy/girl also means a juvenile male/female. If you were a dog breeder, you would use a specific term for “adult female dog”. It wouldn’t be woman, but it would be a term which indicated the dog was capable of producing young and was of breeding age. Similar to how there are terms like chicken/chick/rooster/hen to designate various sex and age based distinctions in chickens. People who don’t need to make the sex/age distinction don’t have as much need for the distinct terms, but if it matters, different terms are used.
It is very unfortunate that the term to indicate gender is also the term used to indicate sex in humans. How nice it would be if one word meant the gender you identified as while another word meant you were an adult of a certain biological sex. As it is, terms like boy/girl, man/woman, male/female are overloaded in ways that will likely cause this kind of confusion and controversy for a long time.

That’s fair enough, but then the immediate objection is why would society refer to that person as a “man” if he or she does not him or herself believe in his or her full maleness? The counter argument is that if the person wants to be referred to as “he” or a “man” then that is what society should respect because, again, no pocket picking or leg breaking.

I know I’m in the minority of this board, but I think it eminently reasonable for someone to say that in my first hypo, someone is being an asshole for not calling me a man because I was born with an unfortunate genetic anomaly and that for my happiness and others similarly situated, society should recognize that I am fully a man.

I think you have to justify why a person claiming to be a certain gender, after having done things that is opposite to the things that gender does, should still be considered, under pains and penalties of social ostracization of being fired.
Emphases added by me.
The boldface phrasing is crucial. First, it seems like you are using something like the one drop rule to define who gets to be called a man. If the person is not “fully a man” or “doesn’t believe 100% in his . . . maleness” he has to justify wanting to be called a man and using male pronouns.
But I think you’d probably agree that if I thought, say, being a stay at home parent was the “opposite” of what men do, that would not make it OK to refer to any man who does that as not really a man, or not believing enough in his own maleness. I understand that you think being pregnant is the sine qua non of being female. But that’s literally immediately adjacent to having the ability, or the correct biological equipment to do so being the defining traits of feminine gender. That both conflates gender and sex, and also allows someone to impose his or her concept of gender on another person.
Gender is socially created. Cultures can have radically different concepts of what is masculine and what is feminine. (Pink is an example that reversed itself over time in Western culture. Men holding hands is one current example across cultures.) Nothing says that there have to be socially constructed genders, or if there are, that there have to be exactly two, at opposite ends of a spectrum. In fact, I’m sure one could plot stereotypically “masculine” and “feminine” traits and actions on more than one axis to come up with something much more complex than two points on a line.
So, there are
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lots of people who don’t identify as men or women, but, English being what it is, and our society being what it is, are constrained to choosing what fits them best. Some of these people may choose “they” pronouns, but some may identify more as one or the other. Their desire or willingness to get pregnant is just one part of that person’s over-all identity, and it’s not for anyone to say that they don’t get to choose what suits them best.
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there are people who reject gender roles or stereotypes in the sense that they like what they like, and do what they want, regardless of whether other people think it’s appropriate for or “opposite” to, their gender, and they don’t feel like they are the “opposite” of their assigned gender at birth. Like the example above, a person who identifies as a woman, while wearing a suit and tie, following “masculine” pursuits, and having a wife, is still a woman if that’s how she identifies.
And, as has already been said, no one has to understand the reasons a man might want to be, or be willingly (or unwillingly) pregnant. It’s important to remember that you typically would not ask or feel you had a right to understand why anyone has chosen to have a child, or bear one, let alone feel that they have to justify it to you in order to be treated with the basic respect of using their pronouns and recognizing the gender with which they identify.

But you’re already on our side. If your coworker John is pregnant, but still asks to be called he/him and John instead of their birth name Jane, you’re going to call them John and he/him, right?
If so, welcome to the woke! That’s all we’re asking from you. If you’re with us already, then all you need to tell them is whatever got you here with us.
It’s going to take a while to go through what I have started, but I’ll start here first.
Yes, of course. I would call him John and a him and ask him how the baby was. But I don’t think that is sufficient because I might go home and not understand John and think him to be somewhat weird.
If the answer was more sufficient than “Just shut up and do what we say” then I might not have to fake support John but be understanding and do more as a fellow human than just call him by whatever name he asks, and the others who openly hate him might have to confront their own biases if presented with a cogent argument.
Persuasion is always better than force.
You really shouldn’t bother faking it. If you don’t want to do something, don’t do it.
Not all what I am saying. I guess I’m not expressing myself well. I, Ultravires, could give two shits about what John does or wants to be called. For some on my side of the political aisle, John represents a left wing threat to do away with the values we grew up with, sort of like how in Dr. Strangelove the commies poisoned our drinking water with fluoride.
Whatever may be true of that larger argument, I know that John at work isn’t part of a left wing conspiracy; he just wants to be happy, so I’ll be glad to call him John. But I want to understand so that I can get over the preconceived notion that John is weird or that I should just do what the latest fad from the left is. Respectfully, I don’t think comments like “well don’t do it if you don’t want to” are helpful because: 1) a person doesn’t have that choice unless they can afford to lose their job, or 2) we want to do more than just go through the motions.

But I want to understand so that I can get over the preconceived notion that John is weird
Maybe, instead of “getting over the notion that John is weird”, just embrace it, and enjoy living with the weird and wild variety of humans who roam this earth. I mean that in all seriousness.

But I don’t think that is sufficient because I might go home and not understand John and think him to be somewhat weird.
You can’t really control how you think of something. If you think it’s somewhat weird, that may be perfectly normal. Over time, if you spend more time with him (and maybe others), that feeling would probably subside.
What you can control is what you say to others and how you respond. If one of your less sensitive friends says, “look at that weirdo? How can she call herself a man when she’s having a baby”, you can respond with, “Hey, what difference does it make to us what he calls himself?”, rather than, “preach it, brother! what a weirdo.”

Maybe, instead of “getting over the notion that John is weird”, just embrace it, and enjoy living with the weird and wild variety of humans who roam this earth. I mean that in all seriousness.
I’ll never get to the other comments at this rate, and have to take a few hours before I’ll be back, but:
We take it as a given that there is a line drawn somewhere, right? We don’t embrace child molesters or murderers, for example, as part of a broad mosaic of humans roaming the earth. We do draw lines at places where we say: this person good, that person bad. There is a strong cacophony of voices on one side of the line that says the idea of a “pregnant man” is absurd. I think that we (and I mean that) need a stronger argument than just “accept it” or “go along with it” or similar. People will not give up things that they have been taught their whole life just because people say to do it.
That’s why I started the thread. Let’s get some good, logical reasons to persuade instead of forcing. There might literally be another civil war if we keep forcing.

I don’t think comments like “well don’t do it if you don’t want to” are helpful because: 1) a person doesn’t have that choice unless they can afford to lose their job, or 2) we want to do more than just go through the motions.
You control your own actions. If you want to do more than go through the motions, then do so. If not, well guess what, everyone knows you’re faking anyway so might as well just do what you wanted.
There were a ton of good, logical reasons. Gender is a spectrum; some transmen may value parenthood to the point of putting their transition aside for a while; it’s difficult for non-cis couples to adopt; people are different. But, mostly, it’s no skin off my nose if a transman wants to have a kid, which isn’t true of murderers or child molesters.
You can recognize that all of transphobia looks exactly like homophobia from generations past and get ahead of it or pull up the rear. No one is forcing anything. The rule at work isn’t “treat transsexuals special”, it’s “treat people with respect.”

And i blurted out, “you’re crazy!” What i meant was not that he was literally insane, but that choosing to go through female puberty, and all the misery that entails, was crazy like keeping chickens is crazy.
We are still close friends. I suffered no adverse consequences.
For what it’s worth, I think maybe you should have?

We take it as a given that there is a line drawn somewhere, right?
Absolutely. And that line is at “bad”, not at “weird”.
Yes, a pregnant man is weird. I’m not the thought police. I think it’s okay if you feel that way. Even if you think it’s absurd. If you are decent to John when he’s pregnant, I don’t care if you think his condition is absurd.

Let’s get some good, logical reasons to persuade instead of forcing. There might literally be another civil war if we keep forcing.
These “logical reasons” you keep asking for will never satisfy.
If you feel unwelcome social forces require violent response then violence is inevitable.

But I want to understand so that I can get over the preconceived notion that John is weird or that I should just do what the latest fad from the left is.
What is happening in society now is that people can identify as whatever gender they like and the definition of what that means is up to them. Your understanding of that gender is irrelevant. Society’s version of that gender is irrelevant. If the person identifies as a gender, then that’s that.
It’s similar to how I might say “I am a comedian”. That means I see myself as a comedian, not necessarily that I match society’s idea of a comedian, Johnny Carson’s idea of a comedian, and so on.
I think your struggle is that you are applying your version of “man” to someone else since they are identifying as a man. But that person may not have any overlap between their concept of man and your concept.

For what it’s worth, I think maybe you should have?
I have several friends who have transitioned physically. I am supportive of them. I don’t actually think any of them are crazy. And I’m not close enough to most of them to comment on their choices at all.
But I am very close to this guy. And he valued my opinion. “Going through female puberty is awful” is a data point. At that point, he knew that I would support whatever he chose, and I’m pretty sure I didn’t harm him.
The point of my anecdote isn’t that “it’s okay to call your friends crazy”, though, it’s that it’s really NOT okay to call people crazy over their gender choices in any situation where there’s any risk of your being thought to believe it’s literally true.
Note that “crazy” in it’s literal meaning is a form of “bad”. (although it’s more broken-bad than evil-bad.)