Here is a problem with modal conditions on knowledge, as traditionally understood. Some of the beliefs we form pertain to things that our own existence is ontologically dependent on. Consider the following scenario:
Two people, Timothy and Titus, look at a photograph of a woman and form the belief She existed at some point. Neither, let us suppose, know anything about the person in the photograph, however, as it happens, she is the mother of Timothy.
Were the belief false, Timothy would not exist. As a result, in the closest world(s) in which the belief is false Timothy fails to form the belief, and there are no close worlds in which Timothy believes that proposition in which it is not true. So Timothy’s belief is both sensitive and safe (according to traditional construals of sensitivity and safety), and necessarily so. Yet, depending on contingent background facts about the photograph, there are situations in which Titus’s belief fails to be sensitive or safe. So, according to traditional accounts of safety and sensitivity, the epistemic status of Timothy and Titus’s beliefs are different, but, according to common sense, this is not the case.
