As I recall it is LUDICROUSLY easy to get the high chaos ending and it's pretty much impossible to come back from. Which is why I was very, VERY careful and got low chaos in my own playthrough, but my hands weren't entirely clean. (also the "peaceful" solutions are pretty messed up, too)

Looking it up, though... your chaos rating goes up if you kill 20+% of the population you find in each mission, and if you kill 50% of the population you're stuck in High Chaos. With some factors bringing Chaos up or down.

There was no reason whatsoever to cut up the unconscious man!!!!