Mechanists have disagreed with one another about how to understand the cause in causal mechanism. New mechanists have in general been at pains both (1) to liberate the relevant causal notion from any overly austere view that restricts causation to only a small class of phenomena (such as collisions, attraction/repulsion, or energy conservation), and (2) to distance themselves from the Humean, regularist conception of causation common among logical empiricists (see also the entry on the   the metaphysics of causation).  Four ways of unpacking the cause in causal mechanism have been discussed: conserved quantity accounts, mechanistic accounts, activities accounts, and counterfactual accounts. (It should be noted that some mechanists have evolved in their thinking about causation.)