Okay, so after running a game wrong, and reading some forum posts, I think I might get the way DW is supposed to work.  I want to recap my thoughts here to get some feedback.

I now understand that monster moves happen when players roll badly enough on a player character move.  But what was getting me, though, was what happens if the player characters never make a move?  Just standing there while a grizzly bear charges, them, for example. 

I worked through that to come to my basic statement of DW philosophy, which I hope is right:  Player character moves are the player's way to alter the course of the narration. 

So if they do nothing, I continue narrating how the bear mauls them, and have them take damage.  If they want to avoid that, they need to make a move of some sort. 

Is that how it's intended to be run?