THe positive theory behind voting is that different people have different values. The claim that group X shouldn't vote is basically the claim that their values shoudln't count. While I recognize that this is the normal idiotic human position...it's also fundamentally broken. Different people have different values. This is positions ONE.
It's one reason to read actual political scientists, and political philosophers. They understand (in general), that the core problem is how to deal with the fact that different people have REAL different values...and that the position that we can ingore everyone else's values and just try to implement our own, while attractive to the immature, skips the hard problem in politics.