Hume’s suggestion that our ideas of causation and necessity should be understood in terms of constant conjunction of objects and the inference of the mind became a central thread of the classical compatibilist position. A key element of this is his diagnosis of the source of incompatibilism as rooted in a confusion between causation and compulsion. What are we to make of this aspect of the compatibilist strategy? The first thing we need to consider is how this argument stands in relation to the other compatibilist arguments already described? We may begin by noting that Hume’s strategy, as built around his “new definition of necessity” (TA, 34/661), appears to concede that a stronger metaphysical “tie” or “bond” between cause and effect would indeed “imply something of force, violence, and constraint”. From the perspective of the (core) compatibilist argument, as developed around the notion of “liberty of spontaneity” and “hypothetical liberty”, this is a basic mistake. The distinction that is crucial to the original argument is that between actions that have causes that are internal to the agent (i.e., motives and desires of some relevant kind) and those that have external causes. It is the latter that are compelled or constrained actions (such as we find in the case of the prisoner who is in chains: EU 8.23/95). This crucial distinction between actions that are brought about through the agent’s motives and desires and those that are not is not compromised by “metaphysical” (non-regularity) accounts of causation. What is relevant to whether an action was compelled or not is the nature of the cause (i.e., the object), not the nature of the causal relation. Hume’s argument relating to the advantages of his “new definition of necessity” directly challenges this – so one or other of these two claims must be abandoned.