Because our society is built on trust and logic. Language is how we communicate with each other and it's a major vehicle for furthering trust. The word "woman" is a fundamental word in our language. It's central and primary. When you claim that "a trans woman is a woman" you are attempting to unilaterally undo society-wide, agreed upon meanings.
@JDMS and
@SomeRandom - I can accept your explanations as to the origins of the phrase.
But trans-activists often claim that sex is malleable, and so the fact that the phrase is used in definitions of trans appears to be a tactic to cast doubt on the medical practice of assigning sex.
No doubt there are rare cases as you mentioned. Rare cases do not undo the basics of biology.
Doing so also ignores the indelible fact that a person is either a biological male or female. Medical transition does not somehow reformat the individual's composition which was established long before they were born and for which it's irrelevant whether they later experience dysphoria.
While it's all well and good to talk about social acceptance and letting people present how they want, the reality of biology is always in the background.
Okay, here we go. Logic is it. The relevant part of logic used by both of you is the classical law of thought as per non-contradiction.
I will use the ontological version here as that is what we are playing:
"It is impossible that the same thing belong and not belong to the same thing at the same time and in the same respect."
Now I will be honest with you 2. This is formal learning that you don't need that to be human, but that you need to understand it if you claim logic as you both do. In other words you are not responsible because I say you are that. You are responsible for be able to use logic, because you do that.
So in practice I will employ reductio ad absurdum both for the contradictions and that you both will in all likelihood will experience cognitive dissonance.
Now for the above definition it has several elements but if effect for thing and respect as to human as a thing,, it is not the tautology that a human is a human, it is that a human is something in a given respect, sense, factor and so on. In the formal sense it is X is Y.
A human is a characteristic observed for the thing human. So far so good.
But now comes the problem. A human is not just one factor. A human is a set of factors, but what we include in that set, is a cognitive social construct.
And here is how it works for we as not you 2 as we define that set and use it against you 2.
We are as humans Y and if you are not Y, you are not humans and in fact you have a disorder, that needs to be removed or you are not humans.
That is what you 2 do.
Humans are a set of factors and some of them are variants that you accept, but others that you don't, because you don't accept that as being human. That is the over reductive logic you both use. A human is Y and if a human is not Y, it is a disorder and not really being a human and needs to be fixed.
And now I am really going to be private for being a variant. I am not trans but for the fact of being a variant I belong to the same class of what variant means for this debate. I have an outward behavior that doesn't match Y. Just as an out of closet trans person, I have a behavior for some cases that doesn't match Y.
The problem for the logic and truth you 2 assume, it is my behavior is not false for logic and truth. But if I internalized your claims, I would end up being harmed, because trying to be Y when I am not, causes harm in me.
So you 2 as representative for normal people are not normal nor abnormal. You are variants like all humans are that, but what you claim is false in the following sense. You can't with objective truth and logic alone establish what it means to be human and you are as a group causing harming in other humans, because you in effect deny that we are humans like you.
And now if you want to call me out as for the rules of the forum, I am going to call you out for in effect claim that I am not a human, because I am not Y.
That is where it ends. Being a human is not just objective truth or your kind of over reductive logic for the category of being a human.
If you cut me, I bleed. If cut you, you bleed. But somehow you are in effect a special positive with truth and logic and I am a special negative with truth and logic. The problem is that it is false.