What are helmets supposed to do? Here are some ideas I've heard about what helmets do:
1. They protect bicyclists when biking on shared streets because bicyclists are unpredictable and will dart in front of motorists who might unwittingly hit them
2. They protect bicyclists from head injury when they crash alone, which is much more common than incidents with motorists
3. They keep the helmet industry going
4. They perpetuate the idea that biking is unsafe
5. They make politicians look like they've done something effective when imposing a mandatory helmet law
6. They keep people off bikes because people don't want this to happen:
I've developed my own perspective on helmets from riding a bike for the last seven years and visiting cities as a bike researcher for the last five. As with many other aspects of bicycling, context matters when considering helmets. If I am going to bike at low speeds on neighborhood streets or on some off-street path, falling off my bike would be about the same as falling while walking.* And, as I have heard helmet critics point out, we're not going to try to get pedestrians to wear helmets, are we?
When I was in Copenhagen and Amsterdam this summer, I could see why wearing helmets there didn't seem important. People biked slowly, and had to pay attention to the many other street users. When I biked in Dublin, I wore a helmet because I felt wobbly with the different orientation of streets, and I wished I had one when I biked in London for the same reason. Where I live, in hilly Seattle, I would feel unsafe without a helmet to protect my brain when I'm flying downhill at speed. (I'm also so accustomed to wearing a helmet that to go without makes me feel naked, so the city's helmet ordinance is a moot point for me.) As for the helmet protecting me against motorists, if wearing a special hat makes your body feel safer when two tons of engine-powered metal are cutting close to your flesh, I'll have what you're having. I pay very close attention to the spaces where I ride, doing as much as I can to compensate for the undeniable fact that many road users are just plain not paying attention. My helmet doesn't solve that problem.
We all count on each other to stay alive when we're traveling, regardless of our transport mode. If we stay alert, and treat city streets like bustling places where different kinds of users are going to pop up, bicycling, walking, and driving will be safer for everyone. What do you think matters more when a kid is biking: wearing a helmet or being around motorists who notice what's going on outside their windows? If our streets are unsafe, that's our collective problem, and not something each bicyclist can fix by wearing a foam hat.
And yet, over and over, helmets come up when a motorist hits a bicyclist, like in the news I read today. How often are the people who tsk tsk over helmets bicyclists themselves? "Concern trolling" is an internet phrase that can mean pretending to care about someone's welfare, but really criticizing their conduct. That's what comes to my mind when I hear people who don't bike talk about helmets. It seems to me that concern trolling about helmets is a veiled statement that the speaker doesn't think bicyclists belong on the street anyway. It would be better if you were gone, they imply, but if you must impose your privileged, entitled presence on roads made for driving, at least wear a helmet. Or if you don't wear a helmet and you get hit by a car, well it's your fault, this line of logic seems to go, as this recent post on a mainstream ladyblog noted. Motorists shouldn't be blamed for hurting somebody that didn't belong there in the first place. That sounds really icky. Google's not driving your car yet folks, you are. While nobody wants to hit others, choosing to drive and yet expecting no other road users to appear is very dangerous.
As for the anti-helmet crowd, I think that part of the resistance comes from bicyclists who know that helmets are not going to change the fact that motorists don't want us in the street. A friend reported recently that while riding the bus he overheard one young man congratulate another for finally biking without a helmet. People seem to think that not wearing a helmet is a grand statement about bikes being "normal." But as bicyclists we often interact with motorists who are not used to sharing roads with nonmotorized transport modes, and some of these motorists make it clear that they don't want to see us as normal at all. We've got bigger fish to fry, and the helmet is a red herring.
*I have a friend who was biking on a quiet street without a helmet, when a little kid walking down the street asked his mom why that guy didn't have to wear a helmet. I bet that lady wished my friend had been wearing his stupid helmet so she didn't have to answer smartypants questions about it.