Newton’s scientific method and the universal law of gravitation

When Newton first presented his argument for the law of gravitation not all were convinced. Huygens, while admiring Newton's achievement in the Principia, was skeptical. Since gravitational attraction contradicts the principles of mechanical philosophy, Newton's theory seemed counterintuitive and even absurd. Leibniz was also critical of Newton's argument. After all, how is one to accept action at a distance without relying on any contact forces or whirling fluids? Newton, on his part, argued that his theory was based on impeccable reasoning. Even if his gravitational force violates the scientific sensibilities of the day, one still has to accept it as fact. Newton explains his attitude towards hypotheses in the General Scholium to Book III of the Principia: For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this experimental philosophy, propositions are deduced from the phenomena, and are made general by induction. The impenetrability, mobility, and impetus of bodies, and the laws of motion and the law of gravity have been found by this method. (Newton 1999, p. 943) According to Newton the nature of a hypothesis does not matter; hypotheses have no place in experimental philosophy. The historical context here is that Newton is primarily concerned with undermining the Cartesian explanation for gravitation as a legitimate alternative to his attraction force. According to Newton, mechanical explanations are no more scientific than occult qualities if we cannot deduce them from the phenomena. The empiricist rhetoric gives Newton an important advantage over his Cartesian opponents.