Why are you hitting yourself?
Deadnaming a trans person -- calling them by their former name that they have abandoned -- is a way to cause harm. It is well established to be harmful to their mental health.
When you deadname a trans person, the harm is not limited to that instant -- other people who see or hear your use of the incorrect name might start using it themselves, especially if they don't know that it is a deadname, thus propagating the harm.
If you deadname a trans person, it is your responsibility to correct the harm. It's no one else's responsibility. It's especially not the responsibility of the trans person you just harmed.
There are many cis people who don't think of themselves as bigots, but who will accidentally deadname a trans person and then refuse to correct their harm. This is a specifically transphobic thing to do.
Sometimes the cis person will perceive only harm to themselves in the situation -- the risk that they will be called transphobic -- and will focus on only that, instead of correcting the actual harm they caused by deadnaming. These people frequently seek any other target for the blame other than themselves, and all too often, they will blame the trans person they just deadnamed.
But you said earlier that was your name, they say. That was the name you gave in the past. I was just saying what you said. It's your fault.
I've heard this particularly from people keeping records of various sorts. "This is the name you said was yours," they say, "so it's what we have to keep calling you. You shouldn't have given us your name if you didn't want us using it."
Claiming that the victim of your harm is simply hurting themself, and that you bear no responsibility for it, is an old schoolyard bullying tactic: "Why are you hitting yourself?"
But I didn't know they changed their name.
If you're saying that, you know now. You can fix it. Correct the harm.
You can't just change history!
History is the story of our current knowledge of the past. History changes all the time as we learn new things.
There are many old views of history that are harmful and incorrect. A trans person's deadname is a microcosm of that. You know their correct name now, and you can fix it.
But we don't have a name change process.
This just means "We've tried nothing, and we're all out of ideas!"
If you're implementing a bureaucratic procedure that you think requires you to deadname someone, you are still deadnaming someone. You have agency. You have the option to not do it.
Processes can be changed. You can point out that the process is asking you to deadname someone, which you won't do, and that's the first step toward finding a new process.
Processes can also be disregarded when they cause harm. You can just write down the trans person's real name instead of their deadname. You can edit an entry in a database. If someone wants to punish you for doing that, they are the one implementing transphobia.
The first name change processes in scientific publishing emerged from allies who refused to knowingly deadname. These heroic accomplices maintained the day-to-day operations of the authoritative repository of papers in a particular field, and when someone* asked them to correct the name of a trans author**, they just did it. That established a precedent, and the formal bureaucratic process came later. Now, a majority of reputable journals have name change processes.
* Specifically, me.
** Also me.
Put an end to this form of bullying
If you see someone using the "why are you hitting yourself?" defense of deadnaming a trans person, call them out. Link them to this page.
Either they will entrench themselves in their transphobia, in which case you now know what kind of bigot they are, or you can work with them to fix the harm.
Notes: I've edited this post, to make parts that were just about deadnaming in general more concise, and to put more attention on bureaucracies that blame the person for having given their deadname.