Last week, a physicians' group called on governments to make helmets mandatory for both children and adults on ski slopes. Lots of people support that. They feel that skiers should not be permitted to decide for themselves whether to wear a helmet because skiing without one is too dangerous. Two days later, Sarah Burke, a champion "superpipe" skier, died as a result of injuries sustained in competition. Burke was almost universally praised as a courageous and talented athlete who died doing what she loved.

Does that make sense?

Maybe it does. I don't know. The question isn't rhetorical.

Risk is everywhere, always, which means we are constantly drawing lines, whether we are aware of it or not. We draw lines between risks that we are willing to personally engage and those we will leave to others. We draw lines between risk-taking that is praiseworthy and that which is foolish, between risks that should be promoted and encouraged and those that should not. We draw lines between what people should be free to decide for themselves and what should be regulated, restricted, or even banned.

But we seldom compare the lines we draw and ask if, in juxtaposition, they make sense.

The injury that killed Sarah Burke was far from her first. Along with the usual torn ligaments and strained muscles, Burke's sport had previously broken her nose, ribs, and back. She was tough, no question about that. Many people praised her for it and were delighted when her sport was added to the Olympics, thanks largely to her prominence and lobbying. But how many of those same people would praise a recreational dirt bike rider who enjoyed off-road stunts so much that he wasn't deterred by a long string of crashes and injuries that finally ended in his death at the horribly young age of 29? Not many, I think.

Does that make sense?

Some people are uncomfortable with these sorts of comparisons. They unsettle what we assume is settled.

Two years ago, the scientist who headed the United Kingdom's government advisory board on drugs published a paper in which he concluded that consuming the illicit drug ecstasy is "no more dangerous than horse riding." He was savaged. Not because he was wrong. He wasn't. The statistics are clear. But stigma plays a huge role in risk perception and showing that a stigmatized activity is no riskier than a socially approved activity upsets intuition and moral judgment. Which makes people angry.

The same scientist then published a paper in which he quantified the harms of various illicit drugs and compared the results to the government's classification scheme, which supposedly categorizes drugs by dangerousness. There was little correlation. The government thanked the scientist for this important insight by firing him.

Another poignant illustration comes by way of "mixed martial arts" (MMA) contests. In MMA, heavily muscled fighters try to beat or choke each other into submission using fists, elbows, knees, feet or any other body part that does the trick. To some, it looks disturbingly like illegal bare-knuckle brawls. Senator John McCain, a longtime boxing fan, famously called it "human cockfighting."

But federal Heritage Minister James Moore couldn't disagree more. "As you know," Moore said at a September reception on Parliament Hill, MMA "has a bit of a stigma still with some folks who are a little bit hesitant about welcoming it into the mainstream of the sporting world. I think that's silly." More and more people agree with Moore. The reception was proof of that, as MPs from all parties gathered to express their support for MMA and have their pictures taken with the stars of the sport. "We want to make sure Canadians understand this is a fast-growing sport, the fastest growing sport in the world," Moore enthused.

It was all very pleasant until a reporter asked Moore why his government would endorse and promote bloody fights between consenting adults while simultaneously insisting that marijuana is so dangerous that consenting adults who choose to smoke it must be treated as criminals. Moore ducked the question.

On Twitter, I goaded the minister. He responded. The comparison is "ridiculous," he tweeted.

If so, I wrote back, it should be easy to explain why. Please do so.

Moore went silent.

I feel for the minister. Juxtaposition can be difficult.

Each year in the United States, high school sports are the cause of an estimated two million injuries, 500,000 doctor visits, and 30,000 hospitalizations. The overall rate of significant injuries is estimated to be 2.44 per 1,000 periods of training or competition, which is high enough to make them an expected part of the experience.

Fortunately, "catastrophic injuries" are far rarer. In the 2007-2008 school year, there were 180. Relative to the number of kids in sports, that's tiny. But still, that is 180 cases of broken necks, paralysis, or death.

So what do we ban? Steroids. They're dangerous, after all.

Does that make sense? "I would prefer my child take anabolic steroids and growth hormone than play rugby," a British scientist who studies doping told the Financial Times. "I don't know of any cases of quadriplegia caused by growth hormone."

Of course there are enormous benefits from playing sports and it's undoubtedly true that in many cases, maybe most, the benefits massively outweigh the risks. But that's not so clear in every case. Look at the coming Super Bowl extravaganza - which celebrates a sport that routinely tears and breaks young bodies, damages brains, and turns elite athletes into pain-soaked middle-aged wrecks. It's family entertainment. The audience is huge, so advertisers love it. One year, the U.S. government spent millions of dollars to air ads about the dangers of marijuana.

Does that make sense?

And what about the "superpipe" that killed Sarah Burke? It's now an Olympic sport and so it will be supported in various ways with public money. In effect, tax dollars will be spent encouraging young people to take up a sport that has an exceptionally high injury rate - a sport that repeatedly battered Sarah Burke's body until, finally, it killed her.

Does that makes sense?

I suspect the answer in many of the cases above is "no." But I'm not certain. The only thing I know for sure is that it's wrong to duck these questions.