 The difference in difference cases isn’t a difference in propositions believed, but in belief-states. John and David are both belief-related to the proposition that David is witnessing John’s being attacked by a bear. But the belief-states that support their being belief-related to that proposition are different. David is in (for example) the “I am witnessing that guy’s being attacked by a bear” belief-state, while John is in the “that guy is witnessing my being attacked by a bear” belief-state. This difference in belief-states generates the differences in their behavior.