No.

It should be like at airports, everything gets checked, even your body gets checked.

This was the opinion of a Greyhound passenger in the wake of yesterday's gruesome murder aboard a bus in Manitoba. She's not alone, but she is wrong.

First, let's understand the rationale for airport security: airplanes aren't like any other mode of transportation. If somebody gains control of an airplane, either by force or by threat thereof, everybody aboard that airplane is completely at the highjacker's mercy. Moreover, there is zero chance of any useful intervention from law enforcement personnel while the situation is ongoing. The highjacker can exact concessions, or, if his goal is less personnel, he can just kill everyone aboard (and plenty more besides, as we saw a few years ago). Hence airport security.

But even here, I have a sense that we might have gone too far. I'm emphatically no expert on airport security, but for me the apparent lesson of September 11 wasn't that we should tighten it a whole bunch, but that we probably couldn't prevent a really determined group of people from highjacking an airplane by force (remember, these were boxcutters, and if they could do it with those they could probably do it with something that we haven't even thought of yet). Ultimately, we take a risk when we get on airplanes, and that risk can't be eliminated. Fortunately, it's already pretty negligible.

Same goes for buses, only more so. Buses, by most measures, are already pretty safe: there are plenty of people around, and there's nowhere for a would-be assailant to escape. Essentially, the only person who would pull something like that is somebody with no particular regard for self-preservation. Unfortunately, as we saw, there are such people. Fortunately, that risk too - the risk of being murdered by a stranger aboard a passenger bus - would be so negligible as to be laughable under other circumstances. I don't know for sure, but I suspect it's about the same as the risk of being murdered in a crowded shopping mall, or walking down a busy street, or in any number of other situations to which we expose ourselves daily. It seems likely that if this guy didn't do this on a bus he would have done so elsewhere at some point.

There's been a lot of examination of the merits of curtailing our liberty in the interests of protecting ourselves against an organized threat. The wise realize, to use a cliche, that if we sacrifice our liberties for the sake of protecting ourselves from terrorists, those terrorists have won. The same isn't true when it comes to protecting ourselves from random isolated threats like the one that took the life of that Greyhound passenger - there are no winners there - but the same principles apply. Fear exists for a solid evolutionary reason, and we're often wise to heed it. But there's a point at which a rational fear (hey, there's a bear on the trail, so we probably shouldn't keep following it) crosses the line into hysteria, when the fear ad the actions it inspires (or prevents) is a greater threat to our well-being than is its target. The notion that bus passengers should have to go through metal detectors, assuming the necessary cost in time and money to do so, is well past that line.