 This tells us what implicature is but not how it happens. For that we need four more ideas. (1) Declarative sentences are standing equipment for calling attention to the propositions they express: the proposition an uttered sentence calls to mind most immediately, reliably, and deliberately is the one it semantically expresses. (2) Once a conversation is under way I can vouch for the truth of any proposition whatsoever by calling attention to it with a sufficient show of deliberateness, if I am plausibly in a position to vouch for its truth and if no other plausible motive for calling attention to it can be expected to come to mind. (3) Suppose I call attention to a thing of any sort with a sufficient show of deliberateness. If the thing strikes my audience as a fully appropriate object of attention in its own right, their attention will dwell on it and go no further; they’ll treat my drawing their attention to it as an end in itself, as it were. But if the thing doesn’t strike them as an appropriate resting place for their attention, they’ll view my drawing their attention to it as a means to some further attentional end, an effort to refer attention onward to some further, ultimately more worthy object. (4) What a cooperative, rational, unconfused speaker is out to vouch for as true in speaking as she does includes both what she is out to get across, the part expected to address her listener’s presumed informational needs, and a rudimentary rationale for speaking as she does, serving to reconcile the words she produces with the supposition that she is cooperative, rational, and unconfused. For without a reputation for being cooperative, rational, and unconfused, a speaker simply won’t be able to collaborate effectively with her audience. Of course, parts of what she is out to vouch for may do double duty, meeting the listener’s informational needs while at the same time helping to preserve or cultivate her own reputation.