  Another obstacle is that we are almost entirely unable to discern the necessary causal connections among the qualities of substances. (And Locke does take those connections to be necessary--but does he construe them in terms of nomological or logical necessity?  Given his view that demonstrative knowledge in natural philosophy is possible for immortals and serves as an ideal for mortals, he seems to be thinking in terms of logical necessity, much like the Aristotelians he was reacting against, a point made by Ott (2009, p. 13).) Locke does find two instances in which we can discern necessary connections between qualities of bodies: “Some few of the primary Qualities have a necessary dependence, and visible connexion one with another, as Figure necessarily presupposes Extension, receiving or communicating Motion by impulse, supposes Solidity.” (E IV.iii.14, p. 546) Apart from these two exceptions, however, necessary connections escape us. In part, this is due to the first obstacle, our inability to discover real essences, due to the minuteness of particles. It is also due, however, to the remoteness of so many bodies, those which lie “beyond this our Earth and Atmosphere…even beyond the Sun, or remotest Star our Eyes have yet discovered” (E IV.vi.11, p.586–87, and IV.vi.12, p.587). For according to Locke’s speculations, all things might be causally interconnected in complex ways, such that we could not know one without knowing all of the others with which it is causally connected.