I suppose you mean the OED and not the Oxford Dictionary of Philosophy, which is in front of me with a very different definition. I'm not sure which should be considered "official", but iirc Scrabble requires Collins.

It actually doesn't matter, because neither definition is relevant, because the only definition that matters is the one that's defined in the author's paper. The author uses this to set up their argument's scope. (Oh hey, that's Oxford's very next entry! Although they only talk about it in terms of logic.)