 Another ongoing debate regarding physical probabilities concerns whether chance is compatible with determinism—see, e.g., Schaffer (2007), an incompatibilist, and Ismael (2009), a compatibilist; see Frigg (2016) for an overview. Relatedly, an important approach to objective probability that has gained popularity involves the so-called method of arbitrary functions. Originating with Poincaré (1896), it is a mathematical technique for determining probability functions for certain systems with chaotic dynamical laws mapping input conditions to outcomes. Roughly speaking, the probabilities for the outcomes are relatively insensitive to the probabilities over the various initial conditions — think of how the probabilities of outcomes of spins of a roulette wheel apparently do not depend on how the wheel is spun, sometimes vigorously, sometimes feebly. See Strevens (2003, 2013) for detailed treatments of this approach. 