I happen to have a copy of Philosophy of a Knife, and I couldn't watch all of it either Bob, don't feel too bad.
Unlike Men Behind the Sun, (which is in a similar vein) Philosophy is LONG. Like LOTR long. 4 ****ing hours long. And it has almost no plot (I challenge anyone to spot the plot without a guide) and practically no dialogue. It's just constant terrible horrible things.
And I can totally understand why it is like that.
See, the thing with a lot of these kinda movies is that they are aimed at hardcore horror freaks and as such are just regular horror movies juiced up to 11. And thats why I can watch them and not care too much. They are schlock exploitation that's aimed at desensitized people. The gore is shocking, the rest is often laughable.
And that's why Philosophy gets my vote for the 'best atrocity flick'. The whole point is to put in front of you things with almost no context or explanation just pain and horror and degradation. Which is pretty much what the people experimented on got. But its not really a movie. It's art.