Scotland allowed 16 and 17 year olds to vote in yesterday’s historic referendum on independence. Georgetown political theorist Jason Brennan, author of the excellent book The Ethics of Voting, makes a strong case that the United States should do the same thing:

Scotland decided to trust its 16-year-olds to vote in the biggest question in its history when the country headed to the polls this week for a referendum on independence. Americans, in contrast, don’t even trust theirs to help pick the county sheriff. Who’s right?
Many here might be skeptical about the idea of the United States following Scotland’s lead in lowering the voting age. The trouble is that the main reason most people cite for barring 16- and 17-year-olds from voting looks like an equally good reason to stop most American adults from voting, too.
The key argument against letting high school juniors vote is simple: Their choice would affect all of us. After all, a voter chooses for everyone, not just him or herself. Many worry that most 16-year-olds lack the wisdom or knowledge to cast smart votes, so we don’t let them vote because we want to protect ourselves from their decisions.
And this concern is often grounded in reality — young adults are indeed in many cases profoundly ignorant about politics. But if that is a reason for excluding them from voting, it is surely a reason to exclude almost everyone else.

As Brennan recognizes, the strongest argument against letting 16 year olds vote is that they lack relevant political knowledge. But, he points out, the evidence indicates that most adult voters are also ignorant. Just this week, an Annenberg Public Policy Center survey found that only 36 percent of American adults can name the three branches of government, only 38 percent know that the Republicans control the House, and a similar percentage know that the Democrats control the Senate. These results are consistent with much previous survey data, going back decades. Brennan points out that the evidence does not support claims that people over the age of 18 have some sort of improved wisdom or judgment that enables them to make better political decisions, regardless of the extent of their factual knowledge.

There is, however, some evidence that young voters are more ignorant, on average, than older ones. Brennan correctly responds that that concern does not justify excluding those younger voters who do have at least as much political knowledge as the average adult voter. For example, he suggests that we could allow people under the age of 18 to vote if they can pass the citizenship test administered to immigrants who seek to become naturalized. Most native-born American adults probably could not pass that test; so letting children vote who could pass it would actually increase the average knowledge level of the electorate rather than diminish it.

I myself have advocated for letting knowledgeable children vote since 2008. As I explained in my very first post on the subject, if the knowledge problem is set aside, there is a strong case for allowing relatively well-informed children to vote:

[I]t’s probably true that the average child knows a lot less about politics than the average adult, and that may be a good reason to deny most children the franchise. But why deny it to all of them? If a minor can pass a test of basic political knowledge (say, the political knowledge equivalent of the citizenship test administered to immigrants seeking naturalization), why shouldn’t he or she have the right to vote? Such a precocious child-voter would probably be more knowledgeable than the majority of the adult population. Giving her the right to vote would actually increase the average knowledge level of the electorate and thereby slightly improve the quality of political decision-making. I’ve met twelve-year-olds with far higher levels of political knowledge than that of the average adult. You probably have too.
Once the knowledge objection is off the table, all the arguments for giving adults the right to vote also apply to sufficiently knowledgeable children. Like… adults, children have a claim to the franchise because government policies affect them too, because otherwise their interests might be undervalued in the political process, because it affirms their status as citizens with equal rights, and so on.

There are other possible arguments for denying the franchise to knowledgeable children. But they have little validity, and some are uncomfortably similar to long-discredited rationales for denying it to women:

Some people might worry that even knowledgeable child-voters will be “unduly” influenced by their parents’ preferences. Given the existence of the secret ballot, I doubt that this would be a major problem. Moreover, children who are knowledgeable enough to pass the test and interested enough to take it will probably have at least some political ideas of their own that aren’t easily susceptible to parental suasion. In any event, I’m not sure that the possibility of parental persuasion would necessarily be a bad thing. The objection is in fact similar to one of the arguments once raised against giving women the right to vote – that they would be unduly influenced by their husbands or fathers. Husbands will often influence the views of their wives (and vice versa); similarly, parents will influence those of their children. That doesn’t by itself justify denying either married people or children the right to vote….
[C]hildren might lack maturity or life experience, as well as knowledge…. I’m just not convinced that either is tremendously useful for voting. Most voting decisions have to do with complex, large-scale policy issues that can’t easily be weighed based on personal experience. Realistically, even most adults have little life experience that is directly useful in assessing difficult policy issues… At the very least, it seems to me that superior knowledge might well outweigh inferior maturity and life experience. And I’m only advocating giving the franchise to children who can demonstrate knowledge levels superior to those of the average adult voter…..
[Some cite] the value for voting of such “adult” experiences as holding a job, paying taxes, owning property, and so on…. I’m skeptical that these experiences greatly improve the quality of voting decisions. Even more to the point, however, we don’t exclude from the franchise the many adults who lack some or all of these experiences – even if they are also ignorant of even the most basic political knowledge. If lack of life experience is not enough to justify exclusion of even the most ignorant adults from the franchise, I don’t see why it should be considered sufficient to exclude vastly more knowledgeable minors…
One can argue that the exclusion of children is more permissible than that of comparable adults because it is “only” temporary. But every election leads to policy decisions that have permanent long-term effects. Knowledgeable children who were denied the vote in 2004, 2008, and this year, are going to be massively affected by the decisions made by the winners of these elections. And, of course, the exclusion of adults who don’t have jobs or other relevant life experience might also be temporary, lasting only until they manage to get that experience.

As I have noted previously, it may not be easy to incentivize the government to design an unbiased knowledge test for children that does not unduly favor supporters of the incumbent ruling party. But the idea of extending the franchise to knowledgeable minors is one that should be taken seriously. It could simultaneously eliminate an injustice and improve the quality of the electorate.