Joseph Kenny, O.P.


��� Introduction (below)

  1. Definition of Philosophy of Nature
  2. The Principles of Nature: Thomas Aquinas to Brother Sylvester
  3. The subject of Natural Science
  4. Causal explanations in the Science of Nature
  5. Motion
  6. The Infinite
  7. Place, Space, Void
  8. Time
  9. The kinds of motion & their contrariety
  10. The divisibility of motion
  11. The cause of motion
  12. A First Mover
  13. Thomas' five ways


Philosophy of nature is in a way the most important course in Philosophy. Metaphysics and philosophy of the nature of man are more important because what they treat, but these sciences are grounded in Philosophy of Nature, and without a good Philosophy of Nature there can be no sound metaphysics or philosophy of man.

I share the conviction of many that Thomas Aquinas' philosophy is essential for any sound philosophy of nature. Yet it cannot be denied that the chemistry and physics he inherited and accepted is flawed in many important points, and these affect his fundamental philosophy of nature, since for him physics, chemistry and biology formed an integral whole with the basic principles studied in the Physics. His geocentric universe is a small problem in comparison with his lack of appreciation of the full implications of the idea of impetus.

There are also many erroneous ideas circulating in introductions to modern texbooks on the physical sciences. These and other problems are faced in this book, to the extent that is possible in an introductory work such as this. Some of the passages of modern authors have been taken from Vincent E. Smith

Plan of the course

Following Aristotle's Physics and Thomas' Commentary, we have the following tasks to do:

  1. To determine what is Philosophy of Nature in the scheme of philosophy and science.
  2. To determine the fundamental principles of nature, with an examination of the different meanings of nature.
  3. To define the subject of natural science.
  4. To examine causality and chance, because natural causes are the principles of demonstration.
  5. To analyze the meaning of motion and its various species, since motion is the basic characteristic of natural things.
  6. To analyze several subsidiary concepts, such as the infinite,
  7. place, space, void,
  8. time.
  9. To analyze further the three species of motion, replying to various objections to the possibility of motion.
  10. To analyze the divisibility of motion and rest, towards determining the efficient cause.
  11. To determine the what is the first mover or ultimate efficient cause of motion, and
  12. To review all the various arguments for the existence of God.