 Comparative cp-laws are connected to the invariance approach of Woodward and Hitchcock (see §6.2 below). According to this account, a cp-generalization expresses what would happen if an intervention on \(X\) would  occur.[10]  In causal graph theory, an intervention is defined as an operation which changes the value of \(X\) and decouples \(X\) from all causal parents of \(X\) (cf. Pearl 2000, 23f, Woodward 2003, 98). This notion of an intervention has the effect that a change of \(X\)’s value (as the result of an intervention) will not change the value of any other \(X\)-independent variable—which is exactly what is required by a comparative cp-law.