What Does "Fair" Mean In Sexual Differences?

Megan McArdle mars an otherwise fine piece on sexual differences with this graf:

It wouldn't prove that we can stand pat even if we've realized that we've reached a place where female and male brain differences are accounting for most of the difference in workplace outcome. If male brains do a better job at certain things -- say, competition or negotiating -- then the answer might be "we need to restructure the economy so that it better rewards female talents." Science can tell you what is. It cannot tell you what ought to be. And after all, gents, we are the majority. Fair is fair.

Once you've decided on arbitrary visions of "fair", you're lost. This, fundamentally, is an argument with the idea of competence. How do you make the world "fair" save by imposing outcomes you prefer on third parties who otherwise wouldn't decide in the manner you chose as "fair"? Is it "fair" that there are vastly more male Nobel laureates than female? Shall we distribute track times in this way, too? What about death rates? The world is what it is, and trying to erase fundamental, biologically determined (and thus arrived at via evolution) sexual differences with arbitrary notions of "fairness" will not produce good outcomes, for either sex. I fear McArdle here is subject to the same problems we so often see in modern feminism, in that she looks up at the men with status and power, but ignores the ones beneath her who have nothing or vastly less than her, anyway.