There are two points I've been making in conversation recently:
First: The America I grew up in, and refuse to abandon, has always believed that the essence of courtesy is to treat people the way they wish to be treated. What that means in practice is that when Bruce Jenner reintroduces himself as a woman, you treat her as a woman. Whether you like it or understand it or are comfortable with it is entirely irrelevant. In fact, the more dissonant your feelings, the greater the act of civility.
Second—not to bang the "America" drum too much here, but what the hell, THEY do—America prides itself on being the place where anyone with sufficient will and resolve can achieve the identity he/she has always wanted. We should be grateful to people, like the transgendered who fully transition, who demonstrate that so dramatically. They remind us of our own possibilities. I suspect a lot of the hostility directed at Jenner is from people who gave up on, or are afraid even to begin, their own, far less daunting journeys. In fact I'd bet money on it.
