  The central challenge facing such interpretations is to account for the passages in which Locke speaks as though he accepts the corpuscular hypothesis, most notably those in which he appears to identify the real essences of material substances with the corpuscles’ primary qualities. Jolley (2002) accounts for Locke’s so-called dogmatic tendency in strategic terms. Locke’s Essay targets both Aristotelians and Cartesians, and though agnosticism, which targets the Cartesians, is ultimately the dominant tendency in his thought, Locke emphasizes the explanatory power of the corpuscular hypothesis whenever he has the Aristotelians in his sights. Downing (1998, 2007), meanwhile, interprets Locke’s Essay as developing metaphysical distinctions that constrain physical theory, and then downplays his dogmatic side by taking the corpuscular hypothesis to be truly only a hypothesis for him, and denying that real essence can be identified with primary qualities. Properly understood, Downing argues, the distinction between real and nominal essence is a metaphysical distinction. It is thus more fundamental than the distinction between primary and secondary qualities, which belongs to a particular physical theory, the corpuscular hypothesis. To be worth its salt, a physical theory must meet the metaphysical constraint provided by the real-nominal essence distinction. That is, the physical theory must provide some way of making sense of the notion that material bodies have an internal constitution that is inaccessible to us but that produces those qualities that are accessible. Locke explains his metaphysical distinction using one physical theory, the corpuscular hypothesis, as an illustration, and he often appears to accept or even defend that hypothesis. Still, this is only an appearance, an appearance due to a certain advantage that the corpuscular hypothesis has over other physical hypotheses: it is the theory best suited to our sensory capacities and understanding. Despite its unique status, Locke sees it as only a hypothesis, one crippled by the explanatory limitations evidenced by the problematic phenomena discussed earlier. For Downing, then, Locke’s dogmatic tendencies disappear, leaving only his agnostic side.