Any sufficiently advanced technology is indistinguishable from magic.
It would be far from the most original idea to submit that technology is pretty advanced these days. I have here in my pocket a smartphone (three years old - practically ancient) with a touchscreen of the sort that would have astonished 1993 me. It looks like it came out of Star Trek, for Christ's sake. You can even talk to it and it answers back!
But on Star Trek the ship computer can answer complex questions that require all sorts of interpretation, guesswork and knowledge. It displays a true intelligence. All Siri can do is the same old fuzzy database matching that wouldn't have impressed 1993 me a bit. It's quite cleverly done, but it's a trick. Same as everything else. Our entire IT infrastructure has has been painstakingly constructed, piece by piece, in expensive research efforts. Not useless, by any means, but certainly not magic.
But to politicians it's all the same. They really do see a magic box which does stuff, and us - programmers and IT professionals and other such people - as wizards. They're especially concerned that we seem to be indoctrinating their children into our world without them really understanding it. All they've done is make perfectly reasonable requests like for the magic boxes for displaying information from anywhere in the world be restricted to certain types of information. If we were in a fantasy world that might sense. The magicians have cast their spells to enchant the boxes! Surely they can tweak the spells a bit, so the magic boxes have parental consent controls.
But it's hard. Filters can work two ways. Automatically, or a blacklist. Automatically is rubbish. To get them working properly you need full AI, which ranks alongside nuclear fusion in technologies that we shouldn't rely on ever existing. Blacklists are also rubbish. And, anyway, neither work for an Internet where you can encrypt information just as trivially as registering a new website.
To Cameron we're a bunch of stubborn people who could perfectly well do what he wanted. He thinks the "no", or the "we're doing the best we can" from Google and the ISPs is a negotiating position, rather than a technical reality. He has, after all, never had a job where's he's had to deal with physics and resource constraints rather than just manipulating people. He initially tried sweet-talking the internet industry, but they've not changed their line. So he's resorting to the threat of the law, because that's the next step if you're trying to get your way and you're the government.
Except, he's not alone. The Internet porn nonsense has triggered this particular rant, but we've seen more or less the same problem with copyright (they've blocked Pirate Pay how many times now?), and more recently with libel (hello Lord MacAlpine) and breach of various court orders (Trafigura, Baby P, Jon Venables). And it's not the first time a government has misunderstood the Internet but felt it ought to write a law altering the way it worked (cookies, anyone? oh, and the snooper's charter.) And this is only going to get worse. We saw a few months ago the shocked reaction to a 3D printed gun. Yes, it's not exactly viable as a murder weapon today. But ten, twenty years down the line, what then? It will be as impossible to make a 3D printer suitable for general use yet incapable of making a lethal weapon, as it is to make a phone cable unable to transmit pornography. New Scientist ran a piece about using 3D printers to synthesize drugs, where the research team naïvely thought they could make sure nobody could hack the machines to print bad drugs.
All our laws around publishing and information are stuck in a pre-Internet age, and are fundamentally incompatible with a world where you can't stop the signal. In some areas - because of their manifest absurdity - they have lost popular consent and are effectively unenforceable. Where they have been altered they have had to resort to increasingly draconian measures in the hope of having any sort of effect. An entire sector of law has become obsolete in a generation, due to massive technology shifts. We need to have a serious discussion about what to do about that. And, if kiddies really were being scarred for life by porn (hah), we'd need to come up with an appropriate reaction to that: a mass public information campaign to parents about the services and software and hardware that is already available to restrict their children's use of the Internet might be a good place to start.
David Cameron is not capable of participating in that discussion. Very few politicians are. It's not just that he's not an expert in the subject matter, but that he lacks the humility to take advice from experts (see: Khat). Only a handful of what Charles Stross calls the "ruling party" have ever lived in the real world, where you can't stop a tide by parking your throne on the beach. Computers are not magic boxes, and we can't be heading further into the 21st century with our policymakers acting like they are.