Swindon Borough Council are considering getting rid of their speed cameras. Roderick Bluh, the Council Leader, offered a truly awful argument for doing so on today’s BBC lunchtime news:

When you fine a motorist for speeding, he’s already been speeding. Would it not be best to invest and make sure that speeding is prevented in the first place?

There’s nothing wrong with the idea that it’s better to prevent a crime than to punish one. If we can implement measures (e.g. advertising, improved signage, etc.) to encourage drivers to slow down, then that’s great. However, whatever measures we take to reduce speeding are only going to be partially successful; there will still be some people out there who break the speed limit. So what should we do about them?

There’s no reason why, having done all we can to prevent people from breaking the law, we can’t also try to catch and punish people who break the law. The first problem with Bluh’s argument is therefore that it restricts the options, trying to force us to choose between prevention and punishment when we can in fact have both.

The second problem is that it ignores the fact that speed cameras act as a deterrant. If you know that if you speed you’ll get caught and fined, then there’s a good chance that you’ll slow down. Bluh’s argument thus generalises from the fact that speed cameras don’t stop some crimes (those that they detect) to the idea that they don’t stop any crimes. Speed cameras may not stop people who are fined from speeding, but they do stop plenty of people who aren’t fined from speeding.

Even without those problems, however, there would still have been reason to worry about Bluh’s argument. If its logic worked, and we should get rid of speed cameras because by the time we catch and fine someone for speeding it’s too late to prevent them from speeding, then we should get rid of more than speed cameras. When the police catch and imprison a murderer, his victim is already dead; should we therefore forget about trying to catch and imprison murderers? Bluh’s argument isn’t just an attack on speed cameras, it’s an attack on crime detection and punishment in general, so goes far too far to be plausible.

Whatever decision the Council reaches, hopefully they won’t get rid of the cameras on the basis of the argument above.

We hear a lot about climate change and what we need to do to reduce carbon emissions and so preserve the environment.

One suggestion is that we should replace fossil fuel consumption with biofuel consumption, moving from burning coal and oil to burning ethanol and biodiesel.

Biofuels are liquid fuels made by fermenting plant material such as corn and rapeseed. Although they release carbon when burned, this is carbon aborbed by the plants when they’re grown. Fossil fuels, on the other hand, release into the atmosphere carbon which would otherwise be stored in coal and oil desposits underground. The impact on the environment of burning biofuels is therefore less than the impact of burning fossil fuels.

Or is it? Critics of biofuels point out that to fully understand their environmental impact we need to think more carefully than this.

The process of growing the crops used to make biofuels can be polluting, as can the process of converting the crops into fuel. Areas of rainforest, which act as a carbon sink, are being destroyed to make room to grow biofuel crops; whatever carbon would have been absorbed by the rainforest but now isn’t is a carbon cost of biofuel production.

It may well be that all things considered, biofuels are greener than fossil fuels, at least when they are produced in the right way. What we can’t do, though, is generalise from biofuels being greener than fossil fuels in one way (whatever carbon is emitted into the atmostphere when biofuels are burned is first absorbed when the biofuel crops are grown) to the conclusion that they are greener than fossil fuels full stop.