Objections to Aristotelian Substances

The Argument from Vagueness (David Lewis and Jonathan Schaffer)

Unlike atoms and the whole cosmos, the boundaries of Aristotelian substances seem vague and arbitrary.

Response: the vagueness is only epistemic. The true parts of a substance are essentially parts of it.

The Empirical Argument from Atomism

It is hard to believe that individual particles, atoms, and molecules cannot survive transference from one substance to another (even when this involves different infima species).

Response: this isn’t clearly right, after the quantum revolution. In the Newton-Maxwell-Rutherford world in which atoms are little solar systems, “fundamental” particles seemed to be good candidates for Democritean atoms, with definite identity and persistence facts. Not so clear, post-quantum. We can insist upon it if we want (e.g., Bohmian mechanics), but nothing in quantum theory requires us to think this way.

The worry can also be mitigated by taking on board transferable individual accidents (like accidents of charge, mass, baryon number, or spin). Even if individual particles are material parts of substances, and even if they do not survive transpacific transfer, their individual accidents may.

The Empirical Argument from Quantum Entanglement (Jonathan Schaffer)

Quantum entanglement pushes us toward positing just one substance at the cosmic scale.

Response: how widespread quantum entanglement depends on one’s interpretation of QM (much less widespread on objective collapse theories).

In addition, quantum entanglement forces us to recognize the existence of shared accidents of power and action. Quantum entangled systems are analogous to social groups: the individual substances entangled do share intrinsically in inseparable accidents, but they are not essential parts of the entangled system. They are only contingently entangled. But contingent entanglement is not sufficient for substantial unity.

The Argument from Social Entanglement (Fichte, Hegel, British Idealists)

See above. Aristotelians need not deny that there are fundamental social entities (accidents), just that there are fundamental social substances. We are not essential parts of social groups.