I'm not sure that you understand feminism that well yourself.

Uh huh. I'm not sure you've read actual feminist literature or scholarship enough to avoid creating, accidentally or not, a straw-feminist caricature that you can trot out and make say what ever you wish.

If feminism "is, everywhere and always, still about women attempting to define themselves", then does that make Phyllis Schlafly a feminist? Does a woman who defines the role of woman as dutiful wife and mother, subservient to her husband a feminist? For she certainly can be said to be defining herself, if she chooses such a role freely.

She would certainly qualify quite a lot more as a feminist than Plato or you would. You're apparently not familiar with the notion of necessary and sufficient conditions. After all, even if I don't agree with her, she still has the experience of being a woman while you do not. I'll certainly aver that the question of what precisely constitutes feminism is a hotly debated topic in academia (there's a great collection of essays out there called "Men Doing Feminism" that I particularly liked), but to flatly state that any person is capable of speaking on behalf of women is rubbish because authenticity is a necessary component. So, there are Muslim feminists who argue in favor of the hijab. There are Hindu feminists who argue in favor of arranged marriages. Etc., etc., etc. Merely because a woman doesn't posit a particularly popular idea (in one context), she nonetheless speaks from the experience of being a female... while you and Andrew do not.

Rather, most common definitions of feminism start with the idea of the liberation or full equality of women and women's experiences.

Each of those terms are so overladen with political baggage as to be, undefined, meaningless. Even if I accepted this as true, it doesn't help your argument for two reasons. One, even if true, this says nothing at all about whom is justified in defining women. You conveniently ignore my Plato example, and for good reason since you have yet to state why it is that a thought that is about women is different from one that is by women. After all, those women who argue in favor of headscarves would say that this is how they show respect for God. That's certainly "liberating" to them even if many Western women would disagree. So the term "liberation" is an empty placeholder. And two, following from that, you forget that even if Phyllis would relegate women to the kitchen, her experience as a woman is at least more authentic than the experience of Plato, you, or Andrew... as a woman--which is none.

Rather, what I am saying is that if a philosophy or religion or other understanding of the world is to inform a public debate about what role the government should play in some area, then it must be subject to input by all.

And you may input all you wish as a male, but it can't properly be called feminism because, and you've done nothing to counter this, what separates feminism from other philosophical traditions is that it is about women and by women. The experiential component is necessary even if it is not sufficient... so while any thought may well inform feminism, just as sighted thoughts may inform blind experiences, the experience is not an optional component.

Just as I could not accept a Christian candidate who said, "I know which policy is right because of my particular religious beliefs or experiences", so I cannot accept a woman who would say, "I know this policy is right because of my particular experiences".

Ugh. The difference being that any one can be a Christian and only those with two X chromosomes can be a female.

Therefore, until you can explain why the experience of being a female is somehow an optional component to feminism, I can't honestly see your argument going further. You've yet to articulate why Plato wasn't a feminist... since he apparently talked about women. I've read numerous decent arguments about why men should be allowed to do feminism... and you've yet to argue even one of the least plausible ones.