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The Social Cost

In my memory, he was a reed-thin, almost delicate man, with curly hair and a slightly exasperated demeanor. He was obviously intelligent, and his lectures in my philosophy of law class were always rich in detail and balance. He tackled the big subjects — the death penalty, for instance — with the same even-handedness as others, always probing, always neutral. I was a little surprised when he revealed his love for motorcycle riding, and even more surprised when he expressed such disdain for California’s mandatory motorcycle helmet legislation, which was then on the books but not yet in effect. His opinion still sticks with me today: “I would rather not ride,” he said, “than ride with a helmet.” I’m a little sorry that I didn’t keep up with him after I left school; I don’t know whether he quit riding the following year or two when motorcycle helmets became obligatory for everyone. What I do still find interesting, though, is that the same arguments we tackled then in class over motorcycle helmets are now, nearly twenty years later, being broached yet again, this time in a huge war of words over bicycle helmets.

Elly Blue’s recent Grist article on bicycle helmets sets out the major combatants, with some particular focus on Copenhagenize.com‘s Mikael Colville-Andersen, calling him “the face of the anti-helmet movement.” I’m not sure that this designation is entirely accurate, for it ignores his many antecedents and philosophical compatriots. It also puts him in the uncomfortable position of being an “expert” on bicycle helmets, a moniker that he probably doesn’t want or deserve. Imagine the decision matrix of alien, asked to make a choice about helmet wearing, with the only inputs being these two TEDx videos about helmets, posted only a few days apart:

If I were that alien, presumably a bit risk averse and self-preservationist, I’d probably err on the side of caution, and go with Dr. Gergens’ advice to wear a helmet, even if she seems a bit smarmy and overbearing. She’s an expert on the brain; he’s a photographer who takes many photos of well-dressed women riding bicycles. Her qualifications go far beyond Colville-Andersen’s I-read-a-few-papers “research” résumé.

Any discussion over helmets really comes down to two questions, both related but with different arguments underpinning them:

► Should I, as an individual, wear a helmet?

► Should we, as a public policy matter, make helmet wearing mandatory?

These are yes-no questions, and their possible answers are straightforward:

Personal Choice Public Policy
I wear a helmet I want mandatory legislation
I don’t wear a helmet I don’t want mandatory legislation

The American cyclists I’ve met and read tend to have the ideological viewpoint represented in red: they (mostly) wear helmets while riding but think mandatory legislation isn’t necessary. I share the same viewpoint. I wear a helmet because I feel safer. This is my choice. But the broader issue of whether we ought to require everyone to wear them requires a far different calculus. Public policy is not about personal decisions writ large, but about the (too often negative) impact of collective decisions writ small.

Part of the problem may be that it’s difficult to tease apart motorcycle helmet arguments from bicycle helmet arguments. It’s tempting, of course, to equate the two, given that they both involve two-wheeled machines and both involve helmets, but there are real and substantial differences in their application. For those who haven’t seen them, the best anti-and-pro mandatory motorcycle helmet arguments can perhaps be summarized in two lines:

► Anti: The state has no compelling interest in making helmets mandatory because the decision to wear them or not affects no one else.


► Pro: The state has a compelling interest in mandating helmets because the “collective social costs” (direct medical, reduced productivity, emotional distress) to the society are higher when unhelmeted motorcyclists get into crashes.

Given the U.S. Constitutional principle of substantive due process of law, which requires (among other goals) that legislation be “narrowly targeted” at a “compelling” state interest, the cost argument has done all or most of the work of finding a state interest. Without that, it becomes more difficult to show why the state has any interest in interfering in the private choices of individuals (the anti argument), even if you happen to think helmet-wearing is generally a good idea. It’s probably a good idea to wear shoes while walking on concrete, too, but passing a law to mandate shoe-wearing probably doesn’t make sense.

Whatever its shortcomings, the cost argument probably applies to the bicycle helmet debate exactly opposite to the way it is generally applied to motorcycle helmets; that is, requiring bicycle helmets has a higher social cost than not requiring them. If we accept that there are large societal benefits to cycling — which seems to be universally acknowledged even by people temperamentally skeptical of cycling — this conclusion depends almost entirely on the large question of whether mandatory helmet legislation tends to reduce ridership. The studies on this point are inconclusive, but generally tilt towards answering yes.

Studies aside, helmets must have a negative impact on cycling for the simple reason that they complicate the decision to ride. Helmets have to be purchased, carried, and worn. They are non-integral to the act of cycling, unlike, say, the way an arrow is integral to the act of archery. If they’re lost, they have to be replaced. I could go on…

In the motorcycle domain, there was a collective shrug over the (possible) departure of helmet-hating riders. The government didn’t really care whether we had fewer motorcycles on the road. The public good wasn’t enhanced or diminished by their absence. Motorcycles may reduce congestion, but by some metrics, they can increase (!) pollution, and they do nothing for public health. By contrast, the benefits of cycling mean that reduced ridership would have a negative cost.

Fortunately, at the moment I don’t know of any serious proposals to make helmets mandatory, at least not in California. Los Angeles mayor Antonio Villaraigosa found himself booed when he mentioned such a proposal earlier this year. Maybe that reaction, and more like it, will keep it off the agenda for now … and for good.

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  1. chillikebab
    February 4, 2011 at 2:29 PM

    It’s a pity that Dr. Gergens does not understand the principles of the physics she is talking about.

    Concussion occurs when a rapid change in velocity occurs to the head; the actual mechanism of injury is that the brain continues to move inside the head after the skull has stopped moving – essentially the brain hits the inside of the head in the same way a car occupant hits the interior of the car in a collision.

    These forces (more correctly considered as ‘jerk’ forces than g-forces) can only be ameliorated by slowing the head down more gradually. This is how an airbag works; the car occupant hits the airbag, and as it then deflates they are more gently slowed down over a distance of a 40cm or so, as opposed to coming to a sudden stop when they hit the hard interior of the car.

    However, helmets do very little to slow the head down gradually; typically a helmet will only crush by about 1cm – this offers only negligible benefits in terms of deceleration. This means that helmets do very little to prevent concussion; something that has been recognised recently in research on hockey helmets. A helmet that was able to prevent concussion would have to be very thick indeed in order to slow the head down more gently; however a helmet a foot thick is probably not going to be acceptable to many users!

    What helmets do is to reduce the focal forces on the skull. Whilst the rate of deceleration is not much changed by a helmet, and the total force of the collision is of course unchanged by the helmet (well,to be completely accurate it is increased a little because of the additional mass, but this too is negligible) what changes is how the force is distributed to the head. Rather than being concentrated in one small area, the helmet spreads the force out over a much wider area of the skull. Thus helmets can usefully protect against a skull fracture – however this is a relatively rare type of injury.

    A lot of doctors talk about helmets as if they offer significant protection against concussion. They do not; the reasons why they do not are quite apparent when one considers the basic physics. However, this is not doctors’ area of expertise. We wouldn’t expect a physicist to offer an opinion about the best way to treat a brain injury, so why do we expect doctors to comment on the mathematics of forces and moving objects?

    • February 4, 2011 at 2:49 PM

      Does this analysis apply to motorcycle helmets as well as bicycle/hockey helmets? From what little I read on motorcycle helmets, they seem to have a pretty good track record for the forces they need to dissipate, but I don’t know much about their specific characteristics.

  2. July 16, 2012 at 4:06 AM

    Lots of good stuff here – including the comments – but the “Personal Choice – Public Policy” graphic leaves out the quite varied range of helmet promotion (soft compulsion), especially from government authorities.

  3. July 16, 2012 at 5:02 AM

    A photographer, yes. But as a member of the European Cyclists’ Federation and their workgroup on helmets I am in daily contact with a vast array of researchers, doctors and scientists who are in a constant and productive dialogue about the many scientific studies regarding helmets. They – as well as the private forum for the Bicycle Helmet Research Foundation which is another authoratative group filled with passionate academics who are dedicated to the goal of increasing cycling – are a constant source of inspiration. For four years I’ve been bombarded daily with information, analysis and research and while I certainly don’t wish to be labelled an expert I think that I have done – and am doing – a fair amount of thinking and analysis on the subject. Something I wish other people would do.

  4. KARL
    July 18, 2012 at 4:53 AM

    I think you have missed the point- should we allow people to wear helmets in public even though doing so scares most people into disowning any association with bikes and it’s implied dangers? We can require people expose there faces in public, and letting people armor there skulls has a huge societal cost you clearly have not even though about. you can’t bring luggage on the metra in chicago- why should you be allowed to wear a helmet on a ordinary paved commute? Why should we allow a two second maneuver on the motor controller for amped etc. bikes ‘bionics’ to have enabled by the largely illusioin of protection excessive speeds inviolation of federal law? If your not speeding the selfish beenfit fo the helmet is like not having to finance the precious metals inthe catlytic convertor- fewer injuries and fatalities would result if wearing helmets was as criminal as esxposing genitals- and only the former has an basis in reason to ban. Requrinjg air b ag vests in though an entirely different matter- and requring old cars to retrofit to havethem also a no brainer even thoug hthat enables people to feel secure enough to drive there old car drunk etc. as well.

    I doubt you could goto court wearing a bullet proof vest onthe outside- and if you MUST wear a helmet it better be invisible!

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