The sight of David Cameron weighing into the "internet porn filters" debate – in a move nicely timed to distract the Conservative press from the uncomfortable news of Tory councillors losing seats by the score – isn't exactly one to fill the more web-savvy with confidence. Let's point out first that we've been here before, back in October, when Cameron proposed exactly the same idea: that people taking out new contracts with internet service providers (ISPs) should have to opt in to being able to "access porn". The idea then was that the "big four" ISPs – BT, TalkTalk, Virgin and Sky, who cover 17.6 million of the more than 19 million broadband users in the UK – would let people tick (or untick) a box when they got a new contract.

That time, the proposal emerged from a Cameron meeting with the Mothers' Union. This time, it came from a breakfast conference. This time, there is also the background mood music of a restive right wing in the Tory party unhappy at setbacks and compromise, and the boombox backing of Claire Perry, a Tory MP who chaired an independent inquiry into online child protection. Perry has been calling loudly for filtering of some sort, saying: "We know the current model is failing [and] we need [the ISPs] to acknowledge there is a problem, and we need to do that quickly."

She's not wrong about one thing: there is a problem with internet pornography. The problem, however, isn't that it's too easy to access. The whole idea of the internet is to make things easy to access. Just in case Perry has forgotten, the internet was originally designed as a network that would be robust against a nuclear attack; I don't think even her ire quite matches that. So as long as there is pornography online (and that's going to be forever), people will be able to access it. Furthermore: porn merchants being what they are, they'll try to get their products in front of people as much as they can. And at the other end, you have a lot of adolescent boys who might be underage, but still managed to get their teenage kicks even in the days of print. Put those two at opposite ends of the internet, and nothing short of a direct meteorite hit will stop them connecting.

The Daily Mail, which has been banging the drum for Perry increasingly loudly, may or may not know this truth. Paul Dacre, its editor, hasn't shown much inclination to engage with the internet, beyond dismissing "the Twitters". Yet even as the paper hailed Cameron's move on Friday, it did hold it in a pair of tongs, carefully putting quotes in a headline which said "Internet porn: PM steps in to 'safeguard children'".

So what is the problem with internet pornography? It's that too many parents (and by proxy MPs) think the solution is to regulate the internet, when the answer is to regulate the children – or better still the parents. I write this as a parent with children of both sexes. Frankly, I'm amazed by the tales of parents who let their children have TVs or computers in their bedroom. First of all, it's like telling them not to socialise with you; and it's by socialisation that we work out what we do and don't accept as sensual, and sexual, and pornographic (and where the line lies). Watching TV together means you can discuss what you're watching. Having computers in shared spaces (effectively banning solitary use), using the filtering systems that they have built in – these are solutions that work. They don't need legislation; they don't need complicated filters that will be routed around in a flash (try a search on "VPN filter evade"); they just need to be part of the family. You can't turn off the internet, nor make its denizens respectable (ask Louise Mensch). You can, however, turn off the computer, or explain respectability to your child.

That of course is probably too much to ask. There will be louder calls for filters, even though applying it only to those who change contract will take decades to permeate through (only 5% of people change contract per quarter, and 5 million have never changed).

And even then, once the filters are in place, there will still be a site offering endless pictures of women in bikinis, or see-through dresses, or "hooker heels", to tantalise salivating boys and offer a demeaning message for girls. No, the Daily Mail's website won't fall foul of those filters. Consider that, Claire Perry.

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