 Recall that above, when we translated discourse (33) into Shanahan’s Event Calculus, we arbitrarily chose instants of time \(T_1 ,\ldots ,T_4\) to locate actions in time. This is not how it is done in natural language discourse. The first sentence (Yesterday morning Vincent loaded the gun) states that within some time interval \((=\) reference time) before now \((=\) speech time) there was a time \(t'\) at which a loading event happened \((=\) event time). The second sentence (Then he smoked a cigarette) is linked to this event by the connective then, stating that at some later time \(t''\) a smoking event happened with \(t''\) also being temporally located before now. Analogously for the third sentence: there is an event time \(t'''\) at which Shoot happens and \(t'' \lt t''' \lt\) now. Note that when locating events in time it is always done by existential statements of the form there is a time. So far, however, we have only been dealing with universally quantified variables. Clearly, a formula like \(\forall t\).Happens(Load, \(t) \wedge t \lt\) now cannot be used to represent tense since it would state that Load happens at all times in the past. We have to find a way to introduce existentially quantified information. 