I feel a Genre Discussion of Doom coming on, but by this definition The Lord of the Rings is SF.

Except I'm not defining sf -- I'm offering a number of things that I think are characteristic of sf. The more of those things any given story has, the more likely it is to be sf, but that doesn't mean a non-sf story can't also have some of those characteristics, because these are not impermeable walls we're talking about.