George Berkeley
Berkeley argued that forces and gravity, as defined by Newton, constituted "occult qualities" that "expressed nothing distinctly". He held that those who posited "something unknown in a body of which they have no idea and which they call the principle of motion, are in fact simply stating that the principle of motion is unknown." Therefore, those who "affirm that active force, action, and the principle of motion are really in bodies are adopting an opinion not based on experience." Forces and gravity existed nowhere in the phenomenal world. On the other hand, if they resided in the category of "soul" or "incorporeal thing", they "do not properly belong to physics" as a matter. Berkeley thus concluded that forces lay beyond any kind of empirical observation and could not be a part of proper science. He proposed his theory of signs as a means to explain motion and matter without reference to the "occult qualities" of force and gravity.
Jordanus de Nemore
The medieval “science of weights” (i.e., mechanics) owes much of its importance to the work of Jordanus. In the "Elementa super demonstrationem ponderum", he introduces the concept of “positional gravity” and the use of component forces. Pierre Duhem (in his "Origines de la statique", 1905) thought that Jordanus also introduces infinitesimal considerations into statics in his discussion of "virtual" displacements (this being another interpretation of Duhem) of objects in equilibrium. He proves the law of the lever by means of the principle of work. The "De ratione ponderis" also proves the conditions of equilibrium of unequal weights on planes inclined at different angles – long before it was re-established by Simon Stevin (with his clootcrans -- "wreath of spheres" experiment) and later by Galileo.