 But how are the informants to understand the questions they’re being asked? If they understand the term “possible” as logicians do, as truth in a set-theoretically specified model, then it will be too weak: there are obviously models in which synonymous expressions e.g., “horse” and “Pferd,” or “bachelor” and “unmarried male” are assigned non-overlapping sets (cf. Quine [1953 [1980a], pp. 22–3), so that it’s logically possible for there be a horse that’s not a Pferd, or a bachelor that’s married (again, “a married bachelor” is formally contradictory only if one substitutes synonyms for synonyms; but we certainly can’t appeal to synonymy in trying to define synonymy). But if “possible” is understood (as it ordinarily would be) as merely imaginable, then it will be far too strong, ruling out ideas that the scientifically under-informed might find impossible, e.g., curved space-time, something having the properties of both waves and particles, or completely unconscious thoughts (which, at least, e.g., John Searle 1992, pp. 155–6, and Galen Strawson 1994, pp. 166–7 report having trouble conceiving). As Quine (1953 [1980a]) famously argued, such appeals to informant verdicts will only work if the informants understand the questions as about the very terms the proposed test is supposed to define, viz., “possible” as constrained by synonymy or preservation of meaning. Although, as many have noted (e.g., Williamson 2007, p. 50), there may be explanatory circularities in the best of theories, the circularity here seems particularly vicious, with the relevant ideas appearing not to perform any explanatory work other than bringing in each other’s laundry.