The Nagel model of theory reduction offers a clear vision of the “unity of science” (see the entry on unity of science). According to the model, the unity among scientific disciplines is achieved by reducing theories of higher-level disciplines to the theories of lower-level disciplines. Integration, on that vision, is understood as progress toward a grand, unified body of scientific knowledge. For mechanists, in contrast, integration is piecemeal, local, and pluralistic. What sort of unity could such an “integration” sustain? This question plays out in a back-and-forth between Longino and Tabery concerning disciplinary relationships in the behavioral sciences. Tabery argues that disciplines as disparate as neurobiology and quantitative genetics could pluralistically co-exist and co-inform one another’s causal explanations of complex behaviors by way of mechanism integration. Longino counters that Tabery’s pluralism is only a “moderate” sort because the push for integration ultimately is a push for unification (Longino 2013, 2014; Tabery 2014a,b).  Sullivan (2009) also challenges the push for mechanism integration; she argues that there are significant barriers to the kind of integration mechanists envision. Different laboratories use different experimental protocols to study what they assume to be the same phenomenon; however, these different protocols often in fact target different phenomena, so the integration achieved by combining results is only illusory. These discussions are symptomatic of more general philosophical questions faced by mechanists: How are mechanism integrations actually achieved (as opposed to just asserted)? And what is the relationship between mechanism integration and unification? The new mechanical philosophy stands to benefit from future efforts to situate mechanistic integration into more general philosophical views of integration and pluralism.