Well any debate on "leave no trace" you quickly conclude that leave no trace means leave minimal trace. The environment is able to handle some impact from humans. Sure there are places that are scorched from campfires and trees are stripped bear, but there are other places that you could have a fire in an existing fire ring and no one would notice the missing downed branches that got burned up in a small fire.

How do you know if a fire would leave an acceptable amount of human impact? In my opinion, rangers spend a considerable amount of time thinking about these questions... considering they are often on the frontlines of these fires and have dedicated their lives to protecting our natural resources. I often take their advice. There are many regulations (that change throughout the year) on what campfire policies are acceptable and which are not. If they say NO FIRE, then to me that means no fire. If the rangers say fires are ok, then in my mind it is acceptable. The regs are their for a reason. If I got to an area and it was quite a bit drier or more stripped than what I feel the regs were written for, then I would hold off.

In my mind LNT means follow the regulations and don't participate in wanton destruction that skirts the regulations.