 On most accounts of causation causal claims closely track counterfactual claims. But counterfactual claims are notoriously vague and appear to be highly context-dependent. Consider the following example of how the vagueness challenge for counterfactual claims may arise in combination with the time-asymmetry challenge: imagine a fully elastic collision between two billiard balls on a frictionless plane. What, if anything, can single out putatively causal counterfactuals of the form “If the balls’ initial state prior to the collision had been different, their final state after the collision would be different” from putatively anti-causal backtracking counterfactuals of the form “If the balls’ final state were different, their initial state would have to have been different”? Newton’s laws underwrite both kinds of counterfactual equally: just as different initial states are associated with different final states, differences in the system’s final state have to be correlated with differences in the initial state. Within the context of an initial value problem, in which the initial state of the balls is given and Newton’s laws are used to calculate the subsequent motion of the balls, the former type of counterfactual is the appropriate one, while the context of a final value problem (which asks us to calculate the balls’ prior motion given their final state) suggests the latter type of counterfactual.