be made only by using the general probabilities supplied by a theory to supply chances of particular events.

By chance I mean the definite, single-case probability of an individual event such as rain tomorrow in Tucson. As in this example, its chance depends on *when* the event occurs—afterwards, it is always 0 or 1: and it may vary up until that time as history unfolds. Chance is important because of its conceptual connections to belief and action. The chance of $e$ provides an agent’s best guide to how strongly to believe that $e$ occurs, when not in a position to be certain that it does.[^4] And the comparison between $e$’s chances according as (s)he does or does not do $D$ are critical in the agent’s decision about whether to do $D$. These connections explain why the chance of an event defaults to 0 or 1 when the agent is in a position to be certain about it—typically, after it does or doesn’t occur.

Probabilistic theories may be useful guides to the chances of events, but what they directly yield are not chances but general probabilities of the form $\Pr_{C}(E)$ for an event of type $E$ relative to reference class $C$. 