I suspect that any configurable or discretionary barrier to voting will be used to disenfranchise voters unfairly, at least some times in some places. As it is,

I suspect that any configurable or discretionary barrier to voting will be used to disenfranchise voters unfairly, at least some times in some places. As it is, I'm aware of an age requirement (18 years) and a criminal status requirement (not a felon, sometimes just not incarcerated). A literacy/civics/logic/knowledge/etc. requirement would at best discriminate against people who are uninformed, unintelligent, uneducated, unable or unwilling to take a written test, etc. But they are people whom the laws affect and who should be able to vote. I don't think that they are a comparable category to the exceptions mentioned above, but that's debatable. Most importantly, the test would be optimized to exclude whoever the test designers and proctors consider, knowingly or not, unworthy. I understand the desire to exclude the dummies. I know thoughtful and educated people who espouse the same wish, but it's just too dangerous.