Help me understand then. Is gender entirely separate from sex?
As I am learning, it is. They are gradients on their own lines. See this neat diagram:
http://itspronouncedmetrosexual.com/wp-content/uploads/2012/01/1600-Genderbread-Person.jpg
So, do you use male/female to designate one's sex, and man/woman to designate one's gender?
I still don't know the answer to what words to use. I've seen new words like "xe" and "xer".
The issue is that society is slowly breaking out of a category trap. It's messy, but the facts are clearly shown by the actual existence of humans who do not accept those categories.
If having a penis or not having one has nothing whatsoever to do with being a man, in your view, then how does one's gender get determined?
By the genderbread person, penis is not on the same line as gender. You're still in a strict male/female category. When you abandon that, I think, these new ideas will start to make sense.
Is it something anyone can change at any time on a whim?
I'd say no because, by all accounts, the category trap holds us all and it's hard to break it when you are a victim of it. Homosexuals have to "come out" and that's a gruelling life-changing experience. A lot of these "whims" force people into harm's way. Derision, suffering, sadness and death are the rewards for many who push at the categories.
This is not a whim.
(Another angle on this category trap is that even people who
fit can't speak out against it for fear of being thought deviant or dirty (etc.) by their peers.)
What you seem to be advocating for (correct me if I'm wrong) is a paradigm where "you are what you say and feel you are, irrespective of what your biology is" - is that fair?
Expand your idea of biology. Is the mind not biological? Can one's inner feeling of gender not be said to be biological? I say yes. A transexual, cis or homosexual human is powerless but to be
who their bodies make them be. Our minds are body, don't forget.
Indeed, the very words transexual and homosexual and all the rest are foolish. We have such a need to categorize; it's a red-tape of the mind that strangles reality.
To add, I'd say this sex/gender reality is the same as skin colour. We are in a category trap there too.
That's my rather ignorant and limited take on the matter.