 From a metaphysical point of view, the disunity of science can be given adequate metaphysical foundations that make pluralism compatible with realism (Dupré 1993). Dupré opposes a mechanistic paradigm of unity characterized by determinism, reductionism and essentialism. The paradigm spreads the values and methods of physics to other sciences that he thinks are scientifically and socially deleterious. Disunity appears characterized by three pluralistic theses: against essentialism, there is always a plurality of classifications of reality into kinds; against reductionism, there exists equal reality and causal efficacy of systems at different levels of description, that is, the microlevel is not causally complete, leaving room for downward causation; and against epistemological monism, there is no single methodology that supports a single criterion of scientificity, nor a universal domain of its applicability, only a plurality of epistemic and non-epistemic virtues. The unitary concept of science should be understood, following the later Wittgenstein, as a family-resemblance concept (For a criticism of Dupré’s ideas, see Mitchell 2003 and Sklar 2003).