According to Isaac Newton, the causes for Natural forces to act the way they do are unknown but mathematical principles allow for a geometrical, and thus, mathematical presentation. This is the essence of Newton’s groundbreaking work, The Mathematical Principles of Natural Philosophy. In this three-volume work, Newton presents his 3 Laws of Motion, the Rules of Reasoning in Philosophy, and an attachment essay in the second edition, the General Scholium. The 3 laws of motion are three physical laws which deal with motion and forces acting on bodies.
The first law states that all objects remain at rest or continue moving unless an external force is applied to change its state. The second law states that the force exerted upon a moving object is proportion to the change of momentum in the object and the direction. Finally, the third law of motion states that to every action there is always an equal and opposite reaction. The Rules of Reasoning in Philosophy, meanwhile, are principles of inductive reasoning by which Newton was able to formulate his gravitational law.
According to the rules, only true and sufficient causes of natural things should be accepted; the same causes should be assigned to the same effects; the qualities of bodies that cannot be increased or diminished should be assigned as the universal quality of all bodies whatsoever; and propositions inferred from phenomena should be accepted as accurate or nearly true until a contrary hypothesis is found to challenge the old one.
Finally, the General Scholium summarizes the laws that Newton have formulated and been discussing in relation to the positions and movements of the planets. He also affirms his faith that ultimately Nature has been designed by a Being that governs all things. Thus, the ultimate causes of natural phenomena like gravity or force can never be answered. The scientist can only explain the phenomena.