Lastly, some new mechanists, particularly those interested in providing an account of scientific explanation, have gravitated toward a counterfactual view of causal relevance, and in particular, to the manipulationist view expressed in Woodward (2001, 2003) (see, e.g., Glennan 2002; Craver 2007). The central commitment of this view is that models of mechanisms describe variables that make a difference to the values of other variables in the model and to the phenomenon. Difference-making in this manipulationist sense is understood as a relationship between variables in which interventions on cause variables can be used to change the value of effect variables (see the entry on   causation and manipulability).