Here’s how I’d counter it:
Like others have mentioned, determining who is “ignorant” will always depend on one group of people determining the intelligence of another group, and as we’re all just human, we don’t have a good way of going about that.
But let’s even assume that there is a group of “ignorant” people who we can determine “ought not vote” ... in a country whose constitutional tenets are founded on ideas of we-the-people and elected-government-officials, I can’t imagine any sort of system like that lasting very long, let alone not looking an awful lot like the various historical voter restrictions we had and now recognize as anywhere from unjust to outright condemnable (the original voters were only landowning, which meant voters were almost entirely ”white male Protestants over the age of 21”). Everyone else had to fight for their right to vote, often without access to much education or social standing, often being perceived as innately ignorant/lesser.
Additionally, it seems to me that in a long-term view, restricting voters is counter productive in several ways…
Even if someone is largely ignorant on certain issues, they still have a perspective on the country that is informed by (at the very least) their own experiences. By cutting out a swath of people—deemed “ignorant”—we wind up cutting out the voices of an entire demographic (or more, depending on how we choose to slice and dice ourselves). A democracy means we will all sacrifice a little, compromise a little—and in negotiations, we seem find it much easier to imagine the other person giving up more than we do imagining ourselves giving it up. It doesn’t seem like a huge leap to suggest that should a population be cut out of voting, that population will tend to get the short stick in decisions.
Also, cutting “ignorant” people out of the vote seems to distract from the political issues at hand. Already we have a partisan climate in which those who voted for the “losing” side feel the “winning” side is destroying the country, where people already feel like their votes hardly count—just imagine the reaction people would have when their votes really don’t count… But despite all that political hullabaloo, our voting process is a sort of trial and error. We elect whoever the majority feels will be best at the job, and then we scrutinize that elected official’s every move. Maybe it’s a bit on the extreme side, maybe rhetoric is being manipulated to present certain stories, but we do at least have a process which (in theory) we can use to self-correct ourselves. As much as I wince at the prospects of Trump being president, part of me feels that if the US elects him, then we deserve whatever happens—in the abstracted, long-term view, not in terms of adversely affected individuals—and maybe it can become a moment of self-correction in a larger historical legacy.
Which brings me to what I think is more at fault than any “ignorance” of people… The popular/mainstream discussion/coverage of this election (and the ones I have been old enough to follow) is a bit absurd. Very little time is spent discussing issues or policy in any meaningful way. Much of it is grandstanding and name calling, and whatever someone thinks will get the most attention for being the most outrageous. Probably most frustrating to me, much of the media—despite having different biases on issues—talk about the same handful of events in the same cursory ways, sometimes even with the same phrasing. We are connected to most of the world, yet our popular culture discussion largely lack much of the depth or diversity such an expanse of information offers. If we want to blame anyone for this, it ought to be all of us—maybe especially those in places of media, who took a job to spread information to others—who focus on things as frivolous as hair and skin color, and as outrageous as decontextualized sound bites declaring things that are patently untrue and/or inflammatory and/or mere flimsy rhetoric. I really don’t see how Trump would survive in a political climate that expected decorum and substantiation from a political candidate, and I really don’t see how a group of the population large enough to sway the election could, in that same climate, back a candidate lacking those qualities. I’m not saying the resulting politician would be “ideal”—just that from my own perspective, they would be better.