[rayiner]

Your assumption that the race and gender distribution of the legislature should reflect that of the overall population rests on a normative principle. My point is that normative principle is in tension with democratic principles.

For example, if it is your position that the race of a legislator matters--that one can expect a black or asian senator to do something differently than a white senator--then it is entirely rational for individual voters to prefer representatives of their own race. And in a white-majority society like the U.S., where minorities are geographically distributed amongst a white majority, that means that almost all legislators will be white. Any effort to rebalance that racial distribution would be in tension with the will and self interest of the voters.