OM, I agree fully about the four conditions; I guess my presumption for this thread was that at least one of the four would not be met. The other presumption was that there may be a developing a sub-UL (or "lunatic fringe UL", depending on where you stand) philosophy that, to save the maximum weight, you should take lighter layers and sleeping bags than conditions would indicate and rely on building a fire to help keep you warm - this shifts the decision from "When is a fire appropriate?" to "Always plan to use a fire because carrying the lightest load is the only important consideration."

It was that inferred "light-at-all-costs" philosophy that I felt might be in conflict with LNT - and I'm hoping to find out whether my inference is correct. I fully agree that it is easy to incorporate LNT into lightweight backpacking; in fact, in many ways, they seem to mesh quite well. One example: lightweight philosophy says to reduce food packaging to a minimum by repacking before you leave, which meshes with LNT's pack-it-out philosophy. (Lunatic fringe UL would say, "Burn it in the fire, and you don't have to carry it.")