De Motu (Berkeley's Essay) - Principles or Causes of Motion

Principles or Causes of Motion

Bodies are not known to contain, within themselves, forces that cause motion. Minds, however, are known to cause motion. Such minds are particular, individual causes that are parts of the primary, universal cause of motion.

Bodies are passive, not active. They merely persist indifferently in their states, whether of impelled motion or of rest. Action and reaction are only mathematical hypotheses, not physical qualities. It is useful to refer to action and reaction when demonstrating mechanics, but they are not causes of motion.

We personally experience within ourselves a cause of our bodily motion. It is called soul, mind, or spirit. But, we do not experience a cause of motions inside of other bodies. The ultimate cause of the motion of all bodies is the mind of God. This is known through metaphysics and theology.

Natural science is limited to experiments and mechanics, but it assumes that God was the prime source of motion. The laws of motion, not the cause of motion, are established by natural science. Physicists explain and understand phenomena by showing how they agree with the laws of motion. Fictional, abstract, general terms such as force, action, and reaction are used in theories, formulas, and computations. These cannot be found in bodies.

Through our senses, we actually experience only the effects of moving or resting bodies. The natural scientist is concerned with experiments, laws of motion, mechanical principles, and rational deduction from those principles. The principle and cause of motion itself is a metaphysical, theological, and moral concern.