 The core idea of regularity theories of causation is that causes are regularly followed by their effects. A genuine cause and its effect stand in a pattern of invariable succession: whenever the cause occurs, so does its effect. This regular association is to be understood by contrast to a relation of causal power or efficacy. On a regularity theory, a cause and its effect only instantiate a regularity. No causal powers are posited in virtue of which a cause brings about its effect. Moreover, no metaphysical entities or connections are posited which would ground the regularities in the world. Causation is not conceived of as a metaphysically thick relation of production, but rather as simple instantiation of regularity.