  There are many philosophical accounts of what actually grounds chance, as part of the minor philosophical industry of producing ‘interpretations’—really, reductive analyses or explications—of probability. In this vein we have at least the frequency theory of Reichenbach (1949) and von Mises (1957) (and Carnap’s own explication of probability\(_2\) was in terms of frequencies), the propensity theory of Popper (1959) and Giere (1973), as well as many more recent accounts, notably Lewis’ (1994) ‘Best System’ account of chance (see also Loewer 2004). There is no agreement over which, if any, of these accounts are right; certainly both the accounts mentioned face difficulties in giving an adequate account of chance. The consensus mentioned earlier is not over what actually plays the role of chance, but rather on the constraints that determine what that role is.