One of the results of the Scottish independence referendum has been an increase in support for lowering the voting age to 16 among centre and centre-left politicians. As with Alex Salmond's original calculation (which appears to have been misjudged), some of this stems from the assumption that yoof is instinctively more progressive in its politics, though a more fundamental fear may be that without increased participation by the young the centre of political debate will become ever more geriatric as the population ages.
Polls suggest a large majority against votes for 16 year-olds, though that's probably inertia rather than a strongly held opinion, so this could change if the debate becomes more prominent. Unfortunately, the arguments being made in favour of reform are intellectually lazy and cliché-ridden. Step forward Andrew Adonis: "Given that 16-year-olds are judged old enough to leave home, to marry, to lead an independent life, and even join the Army, it is hard to argue in the modern age that they shouldn’t also have the vote". Well, actually, its pretty easy to argue the opposite because these claims are specious. Tenancy agreements require a guarantor over 18 (or sometimes even 21), marriage requires parental approval until you are 18, and while you can join the British armed forces at 16, you can't be deployed in the field until you're 18.
The equation of voting with rights such as marriage or joining-up is misleading. Nobody has a right to join the army, any more than they have a right to buy a creme-egg or watch Huddersfield Town. This is a simple misuse of the word "right". Marriage is a right, but in the particular sense of having the freedom to choose whom you marry, i.e. not being coerced into an arranged marriage or denied the civic benefits of marriage because of your choice (the argument for gay marriage). It's a negative freedom. There is no right to be married. Singletons cannot march on the town hall and demand a spouse.
Another popular claim is that "if you're old enough to pay tax, you're old enough to vote", which uses tax as a synonym for full-time work. In fact, you start paying tax when you get pocket-money, as most tax paid by the young (and the poor) is in the form of VAT. Equating voting rights with the payment of income tax is not a good argument for lowering the voting age because few 16 or 17 year-olds will pay income tax. This is a result of the increased personal allowance, low wages (the national minimum wage for the under-18 is currently £3.79), and the requirement from 2015 to be in full-time education or training up to 18. More generally, equating taxation and representation risks giving currency to the "no representation without taxation" meme.
Opponents of lowering the voting age to 16 inevitably end up arguing about the fitness of the electorate, which is a reactionary position, no matter how ostensibly liberal they consider themselves to be. Here's an example in respect of the Scottish referendum experience: "the often febrile and divisive nature of the debate may have actually schooled younger citizens in a form of binary politics that is deeply adversarial and reductive. Some young people may even have been discouraged from engaging in established forms of democratic politics. Before we talk about lowering the voting age, we need to start offering young citizens more opportunities to acquire political knowledge, skills and experience." The desire that the young be coached in their civic responsibilities is also found among advocates of a lowering of the voting age, such as Adonis, but that's because both sides start from the patronising belief that the electorate should deserve the vote, a view that is common among the political caste though rarely expressed explicitly.
The right to vote was originally a property right, being tied to landholdings or income, and the age qualification reflected the legal age of majority, i.e. the age at which property could be owned without restraint (the "keys to the door"). The evolution of universal suffrage extended this right to all men and women but retained the age qualification, with the threshold only dropping from 21 to 18 in 1969. This change was the product of a number of factors, but anodynes such as "youth culture" and "changing attitudes" obscure a simple material explanation, namely that the late-60s marked a high-point for the property independence of young workers due to the historic peak in new builds, employment and wages.
It is worth noting that the progressive decrease in the age at which children left home was a trend that started in the 1940s, reached an inflexion point in the late-70s, and has been in reverse ever since. Part of our anxiety about the "boomerang generation" is the worry that living at home into your 30s makes you less than a full adult, because we still equate adulthood and thus civic participation with property independence. The advocacy of a lower voting age is perhaps a grudging acceptance that the link between citizenship and aspirational home-ownership, which has been central to political ideology since the late-70s, is now broken and has become more a negative than a positive in propaganda terms.
But rather than lowering the voting age to 16, why not abolish the age restriction altogether? If having a home of your own or being in full-time work (as opposed to the permanent adolescence of MacJobs and zero-hours) is no longer the assumed standard, what makes a 16 year-old more qualified than a 15 year-old? Why not let every child who wants to vote do so? Would the outcome of elections be noticeably different? Would many 10 year-olds skip from the sweet shop, having paid their VAT dues, to the polling station? No, but the tiny number who would are presumably precociously interested in politics and sufficiently self-assured to brave the disapproving stares. In that sense, they are probably just as informed and engaged as many 50 year olds. The idea that the modern equivalent of the Bash Street Kids might sway the result of a by-election based on whichever candidate promised them a slap-up feed is obviously absurd (but a nice image).
However, we shouldn't consider knowledge or engagement themselves to be qualifications for voting, as this might lead to disenfranchising the ignorant and the lukewarm, i.e. people we don't like or value. Democracy means every idiot gets a vote, though the state has historically tried to restrict the franchise where it can. The UK famously refuses to allow convicts to vote in parliamentary elections, but it also denies a vote to UK citizens who haven't been resident for 15 years, members of the House of Lords, and "people with mental disabilities if, on polling day, they are incapable of making a reasoned judgement" (i.e. you can vote for a Monster Raving Loony candidate but you can't be raving yourself). The UK, like many states, also supports reciprocal resident voting rights in national elections for certain other countries, notably the Republic of Ireland and the Commonwealth.
In fact, why not abolish all these restrictions? We do not penalise the eligible who chose not to vote, so why penalise those who wish to vote but can't? The current restrictions to the franchise are a confused mixture of popular censure (convicts), questionable definitions of fitness ("incapable of making a reasoned judgement" doesn't exclude people who vote based on the candidate's photo), and inconsistent attitudes towards resident foreign nationals (Graham Norton yes, Arsene Wenger no). In reality, there is more likelihood that we will give the vote to 10 year-olds than we will give it to foreigners, no matter how long they have lived here, paid tax and owned property.