Humean Objective Chance

Abstract In this chapter, Humean objective chance (HOC) is laid out and discussed using a number of examples. The theory can be summarized as follows: Chances are constituted by the existence of patterns in the mosaic of events in the world. These patterns are such as to make the adoption of credences identical to the chances rational in the absence of better information, if one is obliged to make guesses or bets concerning the outcomes of chance setups. The full set of objective chances in our world is a Best System composed of many kinds of chances, at various levels of scale and with varying kinds of support in the Humean base. What unifies all the chances is their ability to play the role of guiding credence, as codified in the Principal Principle. The Best System(s) involved in HOC are, as with Lewis, determined by a balance of simplicity and strength and fit; through examples, the right way to understand these notions is sketched. HOC is explicitly pragmatic and is tied to the needs and capacities of limited rational agents.