 As an example, consider the theory \(T\) of classical particle mechanics. For simplicity we will assume that kinematical concepts, such as the positions of particles, their velocities and accelerations are given independently of the theory as functions of time. A central statement of \(T\) is Newton’s second law, \(\bF= m\ba\), which asserts that the sum \(\bF\) of the forces exerted upon a particle equals its mass \(m\) multiplied by its acceleration \(\ba\). 