 Philosophers do not agree upon the relation between reduction and explanation. Some argue that the concept of reduction is on a par with concepts such as causation in that it is intimately tied to certain ‘because’, ‘in virtue of’ or ‘by’ statements, or that there is no fundamental split between explanatory and ontological models of reduction (van Riel 2011; McCauley 1981). Others have held that not only is there a difference between explanatory reduction, which is an epistemological matter, and ontological reductionism, but that there might even be a difference between explanatory reduction and derivation-based models of theory reduction (see the entry on  reductionism in biology;  see also Klein 2009; Dizadji-Bahmani et al. 2010).