It is an odd example you present, and I think most sentient beings would find a good strategy to get the log down to the docks that did not include the total collapse of the smaller man. But for the sake of argument (as this whole scenario is in the first place), much can be gained from the reserves of the third man by applying the whip to his back. One would surely need to weigh the pros and cons carefully, with such action, to evaluate how to get the optimal performance from all members of the team towards achieving the goal at hand. Most people have more in them than they themselves are aware of, and only by pushing the limits of their known abilities, will they ever be able to expand them. An old saying "no pain, no gain" comes to mind. It is trite, and general, but in most cases true.
The Infernals are not chaotic. If I apply the whip to the back of a guild member, or wave a carrot in front of him, it is with a purpose. Torture for the sake of torture is waste... It does not amuse me. We strive to apply a deeper meaning to our actions. Cruelty, applied in a compassionate manner, will benefit all. Not the least of which, the recipient.
With that, I leave this debate. I will not post further on the subject. Good day.
-the Sinistar

Penned by my hand on the 4th of Aeguary, in the year 238 AF.