> OK, then, with that clarification understood, is there anytime when
> science should make the "no possible natural mechanism" conclusion
> instead of the "no known natural mechanism" conclusion?
Science _qua_ science? No.
(It cannot reach the first conclusion, only the second.)
Individual scientists? Yes, depending upont the situation, and always
provisionally.
The scientific community as a whole? Probably not.
(As always, the community tends to focus its resources on problems
it believes it can profitably pursue; however, that does not mean
it should *completely* give up on an "no known natural mechanisms"
problem, no matter how intractible it seems at the moment.)
Loren Haarsma