1. Aquinas on the existence of God ~ slide 1 Aquinas on the existence of God zAquinas’s arguments for God âAquinas’s famous 5 arguments appear in both the Summa Theologica & the Summa Contra Gentiles âWill examine arguments 2 & 5 only âAquinas’s approach in all of the arguments

2. Aquinas on the existence of God ~ slide 2 Aquinas on the existence of God yGod’s existence can be known through God’s effects, i.e, the created world (SCG, chapter 12) âThe 2nd argument y1. We experience causality. y2. Nothing is the cause of itself; causes are other than their effects.

3. Aquinas on the existence of God ~ slide 3 Aquinas on the existence of God y3. There cannot be an infinite regress of caused causes. åIf there were an infinite regress, the effects we experience here & now would not exist. y4. Therefore, there must be some first cause and this we call “God.”

4. Aquinas on the existence of God ~ slide 4 Aquinas on the existence of God âCritique yClarification: a temporal series of causes vs a dependent series. Aquinas is talking about a dependent series. yCan’t we take the observed causality in the world as a brute fact which requires no explanation?

5. Aquinas on the existence of God ~ slide 5 Aquinas on the existence of God yPossible response: If we accept the Principle of Sufficient Reason, then causality must have an explanation. äWhy should we accept the P. of SR? äBecause it is a necessary condition for rationality?

6. Aquinas on the existence of God ~ slide 6 Aquinas on the existence of God yRichard Swinburne (The Existence of God, 2nd ed. rev., Oxford UP, 1991) proposes redoing Aquinas’s 2nd argument äGod is necessary to account for the existence of & the sustaining of the laws of nature which in turn govern the causality we experience.

7. Aquinas on the existence of God ~ slide 7 Aquinas on the existence of God åGod ålaws åcausal events

8. Aquinas on the existence of God ~ slide 8 Aquinas on the existence of God zThe 5th argument â1. The experiential datum: things which lack knowledge act toward ends (goals). äNature displays goal-directedness; it is purpose-filled. â2. Things which move toward ends must be guided by an intelligence. äAnalogy to an arrow shot by an archer.

9. Aquinas on the existence of God ~ slide 9 Aquinas on the existence of God â3. Therefore, there must exist an intelligent being who directs all non- cognitive natural things toward their goals. “And this we call God.”

10. Aquinas on the existence of God ~ slide 10 Paley’s version of the design argument zIn the 19th century, William Paley (1743- 1805) in his Natural Theology; or Evidences of the Existence and Attributes of the Deity (1802), redid Aquinas’s argument. âObserving a stone & finding a watch âI find that it has a purpose & all of its parts have a purpose. âThe watch must have a watchmaker, a intelligent designer.

11. Aquinas on the existence of God ~ slide 11 Paley’s version of the design argument yIt does not matter if somehow the watch was made by a previous watch & that by a previous, etc. This would only increase our admiration for the watch. yAnd it does not matter that we have never seen a watch made. Cf. finding a piece of ancient art.

12. Aquinas on the existence of God ~ slide 12 Paley’s version of the design argument yConcludes that there must be a “designing mind” behind the watch, or watches.  Now the design we observe in the watch exists in nature, but to an even greater degree.

13. Aquinas on the existence of God ~ slide 13 Paley’s version of the design argument  “The contrivances of nature surpass the contrivances of art, in the complexity, subtlety, and curiosity of the mechanism.” “And still more... do they go beyond them in number and variety.” âConclusion: Nature must have a designer and this is God.

14. Aquinas on the existence of God ~ slide 14 Aquinas on the existence of God zCritique of the design argument âThe challenge of Darwin’s theory to all design arguments based on the design of living things yThe theory of natural selection ä(1) Overproduction of pollen, seeds, eggs, & sperm; yet populations remain relatively constant.

15. Aquinas on the existence of God ~ slide 15 Aquinas on the existence of God ä(2) There is a high mortality ä(3) Individuals within a species are not identical; there are some variations. ä(4) Some of these variations are inheritable. ä(5) Some individuals are better adapted than others to the conditions of life and to ecological niches.

16. Aquinas on the existence of God ~ slide 16 Aquinas on the existence of God ä(6) Because of (5), there is natural selection & differential survival. ä(7) Over the long run, (6) results in the rise of divergent stocks issuing from common ancestors. yDarwin’s theory offers a natural explanation for the design of living things. Hence there is no need to appeal to God for this design.

17. Aquinas on the existence of God ~ slide 17 Aquinas on the existence of God yResponses: äCan reconcile God with the natural evolution of the design of living things by stating that God uses evolution to bring about this design. åBut note that this is not an argument for God’s existence; it is a statement of the compatibility of God the designer and evolution.

18. Aquinas on the existence of God ~ slide 18 Aquinas on the existence of God yResponses (cont’d) äSwinburne: God is required to explain the existence and sustaining of the laws governing the evolutionary process.

19. Aquinas on the existence of God ~ slide 19 Aquinas on the existence of God äDarwin’s theory is restricted to the realm of life. Some claim we need God to explain the evolution of the cosmos from the Big Bang. åThe cosmos displays remarkable fine-tuning directed toward the creation of life and mind. This can only be explained by the existence of an intelligent designer.