 Lewis has anyway argued that the doctrine that truth supervenes upon being—and, by implication, optimalism—are an uncomfortable halfway house. He began by trying to persuade us that the retreat from maximalism was already mandated. He pointed out how deeply counterintuitive it is to suppose that negative existentials are true because their truth-makers exist. It seems, offhand, that they are true not because some things do exist but because some don’t. “Why defy this first impression?” (1992: 204). But, more importantly, Lewis pointed out that maximalism was incompatible with what he took to be the master principle governing our thought about modality: Hume’s denial of necessary connection between distinct existences. It is a consequence of this principle that anything can co-exist with anything else that’s distinct. But it is the raison d’être of any truth-maker for the negative existential truth that there are no unicorns—if there is one and whatever else it is like—that even though it is distinct from all unicorns it cannot co-exist with any of them, else it would make it true that there are no unicorns even in circumstances where unicorns existed. Similarly it is the raison d’être of any truth-maker for a general truth that such-and-such are all the facts there are that it refuses to co-exist with any other facts even though it is distinct from them. So if we’re to hang onto Hume’s denial of necessary connexions, we’d better give up the demand for truth-makers for negative and general truths, i.e., maximalism (Lewis 1992: 205, 2001: 610–11).