Hey Carl, no debate here. Just sharing different experiences and perspectives...
If the young idiot in question had not had a sturdy, invincible in his mind, Buck knife, would he have risked such behavior? No. If he had a slip joint pocket knife, he never would have been tempted to abuse it in that manor. Just before lunch, when he was seen doing this, he was told to knock it of. His answer was, "It's a Buck knife!" as if that excused everything. He didn't heed the warning and just after lunch he chopped off his index finger by being stupid. He went out on a limb because he had faith that his Buck knife would not fail him.
This is an excellent point that needs to be underscored. It sits at the very heart of the problem of "risk compensation". Paul Petzold started NOLS, the National Outdoor Leadership School. He was often quoted as saying that a mountaineering helmet increased risk instead of reducing it. With helmets, a climbing party is more likely to climb in the face of rock fall hazards. Without helmets, they are more likely to retreat and seek an alternate route. It's the same principle.
http://en.wikipedia.org/wiki/Risk_compensation
There are studies that show that skiers who wear ski helmets tend to ski faster than those without.
Just to emphasize that we're in agreement on this core problem.
If your cutting brush and you are worried about bumping a knife blade hard enough to close it, you're using the wrong tool. Again, if you are beyond the light everyday common tasks of a slip joint, then why not use a sheath knife? In the garden or any heavy duty use, I've become a huge fan of the mundane red handle Swedish mora number 1. The 10 dollar puuko design is about as fool proof as you can get, rugged construction, and a free swinging scandinavian style sheath that the knife just drops back into as easy as it pulls out. Can be pulled and used while wearing heavy work gloves, and no joints at all to fold or gather dirt and debris.
It is here that we have different experiences perhaps. I'm in total agreement in that I prefer fixed blade knives over locker. But, truth be told, I prefer fixed blade knives over any folding knife, locking or not, for any cutting situation. Heck, I just got back inside after cutting up some tinder for a back yard fire and used my Schrade H-15. Just a wonderful knife to use. But, I use locking folders more often for 3 reasons....
1) Convenience - I hate carrying stuff on my belt and it's just much easier to carry a locking folder than a sheath knife.
2) Social Acceptance - People around me hate me carrying a sheath knife (unless I'm at hunting camp). I can complain about it all day long and it's not going to change a dang thing. If I wore my H-15 on my belt to go to the store, they'd call the cops, whether it's my legal right or not. Just the way things are.
3) Safety - General hard use (within reason and not being stupid like your work mate) can cause a slip joint to slip but at the same time falls very, very short of stressing a well made lock back to the point of failure.
Risk compensation is a tendency, not an irresistible compulsion. If you're bright enough to treat a locking folder as a knife that might close if pressed hard (as in with any stabbing motion or any leverage on it), then I find them to be
safer than a slip joint as they protect against bump closures and the like.
Just to reiterate, I think you're spot on with your basic point that lock invite problems as a general rule. Bicycle helmets have the same effect on the general population. Head injuries remain rather consistent even with helmet laws and studies show that drivers drive closer to cyclists who wear helmets. Better to learn to ride safely.
