Man vs. bear

In spirit, this is what every internet forum post is like. One of the funniest things I've ever seen on the internet:

Could a typical young man, armed only with a knife, (say, six or eight inches long) be trained to consistently "win" fights with a grizzly bear? Assume no element of surprise.

Includes this award-winning response:

In the meantime your knife will probably break. Or worse yet, get stuck. Have you ever felt bear hide? Counting in the thick fur I suspect most blows would glance off. Remember that the bear is moving very fast. And all it needs to do is tag you once and you're toast.

and this counter-response:

I'm talking serious ninja-level combat reflexes here, though. You're probably thinking of just Secret Agent level reflexes. Step it up another notch. I'm imagining the guy is all wall-jumping off trees and doing scissor-kicks and stuff.