Should their be an age cap? At what level of mental capacity should the cap be set? How do you evaluate someone to determine if they are fit to vote?

The problem with rules around voting is that they can always be exploited. I generally believe that the best way to avoid that is simply to remove rules aside from 1 person 1 vote.

The rule for voting is very simple: if you are legally allowed to make decisions for yourself, you are allowed to vote (with a minor exception of certain kinds of criminal convictions). Children and people who are mentally impaired to a severe degree are not allowed to make legal decisions, and are thus not allowed to vote.

What you're proposing is nothing but an absurd over-representation for parents of small children, who will be able to vote twice or even more.

Yea you’re totally correct. I’m mostly responding to those saying mental acuity or general knowledge are reasons to not lower the voting age. That’s a line that’s very challenging to draw equitably.

How does that work for e.g. infants? Doesn’t it give unscrupulous parents of those children an extra vote?

I think the execution is probably difficult, but in principle you can make the requirement that the voter marks a valid ballot by themself.

Interacts badly with mail in and lots of other issues of course.

fine - they have more at stake. Might actually encourage having more children, increase familial voting power

yes of course. 5 or 50. There is no argument for an age requirement, other than gerontocratic one