Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

There is no evidence that shows bike helmets seriously increase the risk of death or injury. Therefore I will wear one.

That is a statement of known facts, followed by a reasonable conclusion. But equally, so is this:

There is no evidence that shows bike helmets seriously decrease the risk of death or injury. Therefore I won't wear one.

The whole point of the helmet 'debate' is that it is fought out as though it made any difference, when really neither side can properly lay claim to anything but the most marginal benefit. It is because the question of whether cyclists wear helmets turns out to be so insignificant that libertarians are so vehemently opposed to compulsion. It is hard to see where the advocates of compulsion get their energy, other than from the seemingly boundless resources of ill directed enthusiasm which infect all authoritarians. If compulsory cycling helmets could demonstrably cut cyclist KSIs by 90%, one might give the authoritarians the benefit of the doubt that they were at least well-meaning, albeit that no benefit of such magnitude would actually require compulsion since every cyclist with a brain worth protecting would voluntarily wear a helmet, but when nobody really knows for sure what the total QALY effect of compulsion would be, not even whether it would be positive or negative, one is forced to conclude that the authoritarians are driven by nothing but the usual egotistical ambition of all politicians to enforce their will on the populace.