 One difficulty faced by such characterizations is that of making clear what the relevant facts are supposed to be. The difficulty is particularly acute in certain debates, for instance in the debate over tense realism. For what is it for a fact to be tensed? It cannot simply be said that a tensed fact is a fact that can be referred to by means of a tensed description of type “the fact that \(p\)”, where “\(p\)” is a tensed sentence. For it is open to a B-theorist to hold that such expressions do refer to (tenseless) facts—e.g., that “the fact that Sam is lying” refers, at any time \(t\), to a fact which can also be referred to (at any time) using the description “the fact that Sam is lying at \(t\)”. Another suggestion is that a fact is tensed if and only if it is transient, i.e., sometimes obtains and sometimes fails to obtain. Yet, it may be replied, even if the proposed characterization does capture some tensed facts, it leaves aside a number of other such facts, e.g., those which can be referred to by “the fact that Sam is currently sitting or not currently sitting” and (barring certain forms of indeterminism) “the fact that if Sam is currently sitting, then it was the case yesterday that Sam would be sitting one day hence”, respectively.