Okay, thinking a little harder, I came up with a possibility. It's not relevant to the whole discussion (hehe) that got to this point, of course, but it *is* something.
*If* I were planning a pushing-the-limits solo dive in which I needed all my air to follow my dive and contingency plan, and if someone wanted to buddy up on that dive, I would have to tell them that I could not share air with them, given my plan. That's not the same thing as saying I would not share air; rather, it is saying that my solo dive plan is not compatible with sharing air.
Would I do such a solo dive? Probably not. I like my "safety" margins. Would it be a theoretically valid reason to say for that dive that I cannot share air? It seems that could be the case. Where I diverge from the "would not share" side of things, however, is that *I* would refuse to allow a *buddy* to dive with *me*, as I would not consider myself to be in a position to be able to carry out the duties that I expect of myself and my buddies.
If I were to say I'd buddy with anyone but would not share air if they need it, I would consider that a very bad sign about my care for those with whom I may dive. On the other hand, saying, "I don't have enough air to share, so I cannot in good conscience allow you to dive with me this dive" shows precisely the opposite. Between two true solo divers, there may be a middle ground, where there is a plan mutually agreed upon that says that this is a solo-and-solo dive and relatively very little assistance may be possible. I would not be able to make such a dive (when I'm around others, I cannot release myself from a basic standard of care -- it's just who I am), but I would not judge two solo divers who *did* make such an agreement.
For non-solo divers, I can't think of a case where it would be acceptable behavior to deny outright the standard of care which is the basis of non-solo diving.
Sorry about that. I'll certainly try again. :biggrin:
Basically, in my head at least, I make a strict distinction between solo diving as a choice and diving alone due to any other reason. To me, solo diving must have intent. If a buddy team gets separated, I do not consider that solo diving -- any incidents that may result are (bad) buddy diving incidents, *not* solo diving incidents. If one person willfully swims away from his buddy, he may be solo diving, but his buddy is not.
Perhaps it's a bit arbitrary, but I believe it yields far better information when you make a distinction between poor buddy diving and willful solo diving. (I don't mind other interpretations of what is and isn't solo diving, of course, but I've chosen the one that makes the most sense and provides the most utility for me.