LONDON — Few figures in English history have been more willfully misunderstood than poor King Canute. In the popular telling, Canute’s arrogance was such that he believed even the tides could be bent to regal whim and that the waves would retreat if he commanded them to do so. (He got wet.) For a thousand years now, the story of Canute and the waves has been improperly held against him. In fact, Canute was probably making the opposite point, illustrating the limits of even royal power. The king could not command, far less control, nature.

Fast forward a thousand years: did you hear the one about the politician who thought he could turn off the Internet? If only, cynics and skeptics sigh and chuckle, he could be more like wise old King Canute. But David Cameron is no Canute; indeed, the British prime minister really does think his government can control at least some of the wilder parts of the web. 

This week, Cameron announced plans to radically curtail Britons’ Internet freedoms and limit what sites and material they can access online. He didn’t put it like that, of course. Instead, Cameron said that service providers would be asked to place automatic filters on every domestic Internet account in Britain. The filters — the design and practicality of which have not yet been tested — would block most pornographic sites on the web. Account holders who wished to view (legal) pornographic images would have to "opt-out" to do so. Some internet service providers (ISPs) already offer filters but households must at present "opt-in" to the restrictions. Cameron’s proposals reverse that presumption.

Cameron insists he has no wish to "moralize" or "scare-monger." Nevertheless, said the prime minister in high moral tones, this is a question "about how we protect our children and their innocence…. [I]n no other market, and with no other industry, do we have such an extraordinarily light touch when it comes to protecting our children. Children can’t go into the shops or the cinema and buy things meant for adults or have adult experiences we rightly regulate to protect them." Cameron stressed, as you would expect him to, that "of course a free and open Internet is vital." But, he added, "when it comes to the Internet in the balance between freedom and responsibility, we have neglected our responsibility to our children." There is, he said, "a contract between parents and the state. Parents say ‘we’ll do our best to raise our children right’ and the state agrees to stand on their side; to make that job a bit easier, not harder."

Cameron is a conservative, not a libertarian and certainly not a libertine. Freedom, as Margaret Thatcher once said, is not the same as license. But whenever a politician invokes principle, the wiser class of voters searches for the political motivation that lurks behind this sudden and convenient conversion to lofty idealism. Principles are fine but pragmatism rules. 

So Cameron’s anti-porn crackdown is both heartfelt — the prime minister has three young children — and cunning. For months, the Daily Mail, Britain’s most powerful and influential newspaper, has campaigned for stricter limits on online pornography. Though a conservative paper, the Mail has not always been on friendly terms with the prime minister. Cameron’s patrician ease sits uncomfortably with the Mail’s pugnacious middle-class cultural conservatism. Keeping the Mail happy makes Downing Street a happier place. Irony aficionados will appreciate that the Mail’s online success (it is the world’s most popular English-language newspaper site) is predicated upon attracting readers to ogle photos of scantily clad female celebrities.

Cameron also knows that his quest for a second term is in large part dependent upon women voters returning to the Conservative fold. The government’s cuts to welfare programs — including child benefits — have hurt the Tories’s standing among women, while the increasing cost of food and energy has been accompanied by a fall in real-term wages. Though the Tories enjoyed a five-point lead among women in the 2010 general election, poll after poll in recent months has suggested the Labour Party currently enjoys a double-digit advantage among female voters.

Hence Cameron’s attempt to appeal to parents and, especially mothers who, it is presumed, are concerned their children are too frequently exposed to hardcore pornography online. A popular clampdown on online pornography also satisfies Cameron’s backbenchers, many of whom view his social liberalism with some suspicion. The Tories in Parliament were dismayed by his decision to legislate in favor of gay marriage and Downing Street’s prediction that a backbench rebellion would be easily extinguished proved hopelessly optimistic. Half the parliamentary party voted against the government’s own bill. So, tacking to the populist right on pornography allows Cameron to throw a consolation bone to his backbenchers and the party grassroots. Many Tories believe that even softcore pornography acts as a kind of "gateway drug" to much more extreme imagery.  

There are other factors prompting the prime minister’s actions too. Two recent high-profile murder trials in which the victims were teenage girls killed by men who had accessed significant quantities of child pornography online prompted calls from MPs and children’s charities to do something to stem the sewer of filth flowing unrestricted into every British home. That means placing filters on all pornography while also requiring search engines such as Google to remove or block search terms deemed too disturbing to be permitted. 

In other words, there exist all the ingredients necessary for a full-scale moral panic reminiscent of past scares about the effects of rap music, video games, or Hollywood movies. It seems improbable — the Internet being the kind of creature it is — that Cameron’s crackdown will have the desired effect. Few people oppose making greater efforts to block access to the so-called "deep Internet" where pedophiles swap files over peer-to-peer networks, but there are justifiable concerns that applying filters to "standard" pornography will also trap plenty of respectable, non-pornographic sites. (For what it’s worth, autocracies like Russia and China have pushed through restrictive Internet legislation using the trusty Trojan horse of protecting children from porn.)

Theoretically — that is, assuming the filtered Internet works — parents would be able to relax, knowing their offspring are less likely to inadvertently (or deliberately) stumble across horrific images that, it is being claimed, might be thought liable to pervert their children’s view of women or children or their own sexuality.

Nevertheless, the Internet is not so easily corralled and it is notable that technology writers have greeted Cameron’s proposals with some skepticism. But even if Cameron’s plans prove unworkable, the mere fact that he has made these suggestions and — that firms such as Google and Yahoo! have agreed to them — is another sign that the days of the old, sprawling, and unruly Internet are coming to an end. Like the Wild West, this is a frontier that may be on the brink of closing.

Many parents are doubtless concerned by what their children can read and watch online. Whether that requires greater government intervention is a different matter. David Cameron’s desire to play nanny is a typical politician’s fetish and one for which, alas, no filters have yet been designed to protect the public.