👉 Newtonianism is a philosophical and scientific theory that postulates that all motion is caused by an object's inertia, or lack of motion. This idea is based on Newton's law of universal gravitation, which states that every particle in the universe attracts every other particle with a force proportional to their masses and inversely proportional to the square of the distance between them. In this theory, the concept of inertial mass refers to the amount of matter an object possesses that remains stationary relative to another object