As part of his recent stand-up routine, Ricky Gervais made a very funny, though politically incorrect, observation about the march and demo in support of lowering the homosexual age of consent to 16: there weren't that many 16-year-olds present, but there were an awful lot of men in their 30s and 40s.
A similar observation could be made about the campaign to lower the voting age. Among the vaguely left wing political classes, there seems to be plenty, or at least, vocal, support for the measure. It's just a pity that among the age group affected, demand for change doesn't go beyond that tiny unrepresentative minority of teenagers who are already politically engaged.
So let's review the case for the change - a case already supported by none other than Ed Miliband, who told Labour conference this week that any government led by him would lower the voting age to 16.
First, the biggie: marriage. If 16-year-olds are deemed mature enough to have sex and marry, why on earth can't they cast a vote as well? And the unpopular answer, I'm afraid, is that they are not mature enough to get married at all. The state has made the correct judgment that, since 16-year-olds are going to have sex anyway, it would do no-one any good for the police to start getting involved in what is already a sensitive area (as it were). But that's not the same as the state saying: "You have our blessing to go and get laid. Oh, and while you're at it (as it were), why not get married too?"
In fact, I can safely say that no-one, not a single person in these isles, is mature (or, if you prefer, "grown up") enough to become half of a married couple. Obviously making judgments about others' choices is one of the worst crimes anyone - let alone an MP - can commit, but getting hitched at 16 is a very, very bad idea. Do not do it. No good will come of it and you will regret it.
Second: the Army. This is always raised as if military recruiters are touring dockside taverns in the dead of night with a press gang, pouncing on teenagers who have had rather too many snakebites with blackcurrant (teenagers still drink that, right?), knocking them out with a blackjack and dumping them aboard a navy ship headed for the Mysterious Orient...
They're really not. Three things you should know about teenagers who join the Army: they do so entirely voluntarily - if they don't want to join, they don't have to. It's their choice. Second, while you can join up at 16, you can't be sent to "fight for your country" until you're 18. Which is also, conveniently, the age when you can have your first vote.
And third, you can only join at the age of 16 with your parent's permission. And I don't think supporters of votes for 16-year-olds are suggesting that you they should only vote if their mum says it's alright.
And the last in the trinity of slam-dunk arguments used to justify this change in the franchise - taxation. If you're old enough to pay tax, you're old enough to vote, apparently. The thing is, there is no age threshold for taxation. We're all subject to it, but that depends on income, not age. Granted, you're more likely to earn a wage when you're sixteen than when you're ten, but in fact there are proportionately fewer 16-18-year-olds earning a full time wage today than at any time in our history. So you could argue that whatever validity this argument has, it has less now than 40 or 50 years ago.
Let's deal with a few of the extraneous arguments often deployed. Regrettably, these often call into service the analogy of the suffragettes or the American revolutionaries.
Emily Davison did not throw herself in front of a horse because she was going to have to wait a couple of years longer than she would have liked to get the vote. To compare voteless teenagers with more than half the population permanently denied a democratic say because of their sex is bordering on offensive.
The citing of the American revolutionaries is even more absurd and historically preposterous, but it's used in the above argument about taxation, which should always be accompanied by representation. UK citizens are guaranteed a vote and a voice when they reach the age of 18; American colonists were taxed without any sort of say whatever on how those taxes were spent or how they were governed. And neither were they promised such in the future. That was their lot. I know teenagers are known for their rebelliousness, but I think our tea chests are probably safe.
But how can under-18s get proper representation without the vote? They can and they do. Representation should not be confused with accountability. There are plenty of people in every constituency who are not allowed to vote at specific elections but who are nevertheless entitled to be represented by their MP. Up to about a fifth of the adult population in the UK is not on the electoral register and have excluded themselves from the right to vote, for example. Nevertheless, they get representation if they ask for it. Citizens of foreign EU states cannot vote for an MP, but can expect the same level of help as anyone else. Similarly, I spend a great deal of time representing asylum seekers, none of whom can vote for or against me at election time. And not that anyone cares very much, but members of the House of Lords are in the same boat as under-18s on general election polling day.
And what's the big deal with having a single age threshold at which you become an adult? Yes, the current array of minimum ages is uneven, but so what? I see no signs of society collapsing because you can have legal sex at 16 but have to wait another year before you can drive, or until you're 18 before you can vote or buy ciggies and alcohol.
One Lib Dem pompously declared that it's fine for the law to encourage young people (he probably said "da kidz") to do good (voting) while discouraging them to do things of which he disapproved (drinking and smoking). I wonder if he would have expressed similar equanimity at the odd 16-year-old who decided to vote BNP? I think I'd rather they smoked a fag...
Crucially, under-18s themselves express no great demand for this change; the politically-engaged 15-year-old is, sadly, an oddity and hardly representative of his age group. According to YouGov, 60% of voters oppose lowering the voting age, and even in the 18-24 age group, nearly the same proportion are against.
But here's the biggest canard in the pro-votes at 16 argument: that this change will re-engage young people in the political process. Like all such claims made in respect of constitutional change, whether it's electoral reform or electing the House of Lords, it's based not on empirical evidence but on wishful thinking. It may or may not turn out to be true, but if (when) such hopes prove groundless, what then? Restore the 18 threshold? Of course not. We will be left with a policy that achieved nothing other than a modest increase in the total number of those who take part in elections, but a substantially lower per centage turnout.
Follow Tom Harris on Twitter: www.twitter.com/TomHarrisMP