 (18) assumes an intensional semantics that is based on possible situations. In possible situation semantics, propositions are sets of possible situations, or characteristic functions of such sets, and all predicates are evaluated with respect to a possible situation. 18(b) is the proposition expressed by (17) in context c. That proposition is a property that is true of a situation s iff there is a situation s′ that is accessible from s and the unique bear in s′ is a grizzly in s′. The modal might introduces existential quantification over possible situations that are accessible from the evaluation situation s (see the entry  modal logic).  The kind of accessibility relation is determined by the lexical meaning of the modal in interaction with properties of the utterance context c (see the entry  indexicals).  In our example, the modality is a particular kind of epistemic modality that relates two situations s and s′ in a context c just in case s and s′ are equivalent with respect to the information available in c, that is, whatever evidence about s is available in c isn’t specific enough to distinguish between s and s′ (epistemic contextualism). Evidence that counts as available for epistemic modals might include the distributed knowledge of the discourse participants (see von Fintel &amp; Gillies 2011), other available sources of information like ship’s logs or computer printouts (Hacking 1967, von Fintel &amp; Gillies 2011), but, interestingly, not necessarily information that happens to be hidden from sight like test results in sealed envelopes (de Rose 1991), babies in wombs (Teller 1972), weather conditions behind drawn curtains (Gillies 2001), or details of animals obscured by darkness. Suppose the actual bear in Bear Sighting is in fact a black bear, and not a grizzly. Since it is night and we can’t see the bear very well, the evidence we have about Bear Sighting when I utter (17) cannot distinguish the real situation from many merely possible ones, including some where the bear is a grizzly and not a black bear. This is what makes my utterance of (17) true.