I've been going slow through the SEP article on intrinsic properties, and came across this intriguing gem:
(The locution ‘state of affairs’ is used differently by different philosophers. Here it is being used to refer to the zero-place analogues of one-place properties and multiple place relations. Just as a property is a way of a thing is or fails to be, a state of affairs, under our usage, is a way things are or fail to be.)
I've never seen this definition before, not to my memory anyway, but it seems useful, both as an analysis of the state-of-affairs concept itself, but also on its own terms (i.e. I would be minded to accept the existence of zero-place counterpoints to properties and relations, regardless of whether I thought "states-of-affairs" was a phrase better reserved for some other conceptual phenomenon). If zeroth-order logic is usually credited with being propositional logic, however, is there a mismatching of definitions, here? For first-order logic is predicate logic, second-order logic involves predicates of other predicates (meta-predicates), or sets-of-sets (where the first-order case is sets-of-(not-sets)?). Granted, if states-of-affairs enter into the obtainment relation, and this is a truth-like or fact-like status, and truths and facts are propositional either as is or in their consequences, perhaps there is not so much of a mismatch.