  When Newton took for granted that there is just one kind of universal matter and refused to include gravity as a primary property of matter because of worries about the ontological status of force, he was playing the role of a natural philosopher in the tradition of the mechanical philosophy. When he offered a pragmatic justification of his specification of the force of gravity independently of how that force might be explained he was acting as one who sought to develop an experimentally confirmed science independent of the kinds of ultimate explanation sought by the mechanical philosophers. His atomism contained elements of both of these tendencies. A sympathiser could say that whatever the philosophical problems posed by forces, Newtonian atomism was a speculation that at least held the promise of explaining material phenomena in a way that mechanical atomism did not and so experimental support in the future was a possibility. A critic, on the other hand, could argue that, from the philosophical perspective, the introduction of force undermined the case for the clarity and intelligibility of mechanical atomism on which its originators had based their case. From a scientific point of view, there was no significant empirical support for atomism and it was unable to offer useful guidance to the experimental sciences that grew and prospered in the seventeenth century and beyond.