Aquinas's 2nd & 5th arguments for God - 1 Aquinas’s arguments for the existence of God zAquinas’s famous 5 argument appear in both the Summa Theologica & the Summa Contra Gentiles zWill examine arguments 2 & 5 only zAquinas’s approach in all of the arguments yGod’s existence can be known through God’s effects, i.e, the created world (chapter 12)

Aquinas's 2nd & 5th arguments for God - 2 Aquinas’s arguments for the existence of God yThe 2nd argument x1. We experience causality. x2. Nothing is the cause of itself; causes are other than their effects. x3. There cannot be an infinite regress of caused causes. –If there were an infinite regress, the effects we experience here & now would not exist.

Aquinas's 2nd & 5th arguments for God - 3 Aquinas’s arguments for the existence of God yThe 2nd argument (cont’d) x4. Therefore, there must be some first cause and this we call “God.” yCritique xClarification: a temporal series of causes vs a dependent series. Aquinas is talking about a dependent series.

Aquinas's 2nd & 5th arguments for God - 4 Aquinas’s arguments for the existence of God xCan’t we take the observed causality in the world as a brute fact which requires no explanation? xPossible response: If we accept the Principle of Sufficient Reason, then causality must have an explanation. Why should we accept the P. of SR? Because it is a necessary condition for rationality?

Aquinas's 2nd & 5th arguments for God - 5 Aquinas’s arguments for the existence of God xRichard Swinburne (The Existence of God, 2nd ed. rev., Oxford UP, 1991) proposes redoing Aquinas’s 2nd argument God is necessary to account for the existence of & the sustaining of the laws of nature which in turn govern the causality we experience.

Aquinas's 2nd & 5th arguments for God - 6 Aquinas’s arguments for the existence of God –God –laws –causal events

Aquinas's 2nd & 5th arguments for God - 7 Aquinas’s arguments for the existence of God zThe 5th argument y1. The experiential datum: things which lack knowledge act toward ends (goals). Nature displays goal-directedness; it is purpose-filled. y2. Things which move toward ends must be guided by an intelligence. Analogy to an arrow shot by an archer.

Aquinas's 2nd & 5th arguments for God - 8 Aquinas’s arguments for the existence of God zThe 5th argument (cont’d) y3. Therefore, there must exist an intelligent being who directs all non- cognitive natural things toward their goals. “And this we call God.” zIn the 19th cenutury, William Paley ( ) in his Natural Theology; or Evidences of the Existence and Attributes of the Deity (1802), redid Aquinas’s argument.

Aquinas's 2nd & 5th arguments for God - 9 Aquinas’s arguments for the existence of God yAnalogy between a clock and the clock-like design and behavior of the universe as a whole and especially living things.

Aquinas's 2nd & 5th arguments for God - 10 Aquinas’s arguments for the existence of God zCritique of the design argument yThe challenge of Darwin’s theory to all design arguments based on the design of living things xThe theory of natural selection (1) Overproduction of pollen, seeds, eggs, & sperm; yet populations remain relatively constant.

Aquinas's 2nd & 5th arguments for God - 11 Aquinas’s arguments for the existence of God (2) There is a high mortality (3) Individuals within a species are not identical; there are some variations. (4) Some of these variations are inheritable. (5) Some individuals are better adapted than others to the conditions of life and to ecological niches.

Aquinas's 2nd & 5th arguments for God - 12 Aquinas’s arguments for the existence of God (6) Because of (5), there is natural selection & differential survival. (7) Over the long run, (6) results in the rise of divergent stocks issuing from common ancestors. xDarwin’s theory offers a natural explanation for the design of living things. Hence there is no need to appeal to God for this design.

Aquinas's 2nd & 5th arguments for God - 13 Aquinas’s arguments for the existence of God xResponses: Can reconcile God with the natural evolution of the design of living things by stating that God uses evolution to bring about this design. –But note that this is not an argument for God’s existence; it is a statement of the compatibility of God the designer and evolution.

Aquinas's 2nd & 5th arguments for God - 14 Aquinas’s arguments for the existence of God xResponses (cont’d) Swinburne: God is required to explain the existence and sustaining of the laws governing the evolutionary process.

Aquinas's 2nd & 5th arguments for God - 15 Aquinas’s arguments for the existence of God Darwin’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. –The cosmos displays remarkable fine-tuning directed toward the creation of life and mind.

Aquinas's 2nd & 5th arguments for God - 16 Aquinas’s arguments for the existence of God –Illustrations of this fine-tuning –The expansion rate. Stephen Hawkings: “If the rate of expansion one second after the Big Bang had been smaller by one part in a hundred thousand million million it would have recollapsed before it reached its present size”

Aquinas's 2nd & 5th arguments for God - 17 Aquinas’s arguments for the existence of God –The formation of the elements. If the strong nuclear force were slightly weaker we would have only hydrogen in the universe. If the force were slightly stronger, all the hydrogen would have been converted to helium. In either case, stars and compounds such as water could not have formed.

Aquinas's 2nd & 5th arguments for God - 18 Aquinas’s arguments for the existence of God –If the nuclear force had been slightly stronger, carbon would all have been converted into oxygen. –Conclusion: This fine-tuning of the evolution of the universe can only be explained by the existence of an intelligent designer.