God's Existence

Thanks for the debate Sotiras. We will be delving into philosophy and modal logic to prove God's existence. These are some classical arguments advanced by modern philosophers to prove God's existence. Hartshorne Ontological Argument (P1) God is perfect (from the definition of God) (P2) Perfection cannot exist contingently. (premise) (P3) If God exists, then he necessarily exists (exists in all possible worlds). (from P1 and P2) (P4) God is not impossible (there is a possible world in which God exists). (premise) (P5) If p is necessarily true, then p is actually true (modal axiom). (P6) If God necessarily exists, then God actually exists. (from P5) (P7) If God does not actually exist, God necessarily does not exist (does not exist in any possible world). (modus tollens from P6) (P8) God either actually exists or does not actually exist (Principle of Excluded Middle). (P9) God either necessarily exists or necessarily does not exist. (substitution, P6 and P7) (P10) God necessarily exists. (P9, P4, disjunctive syllogism, i.e. if there is a possible world in which God exists, it cannot be the case that he does not exist in all possible worlds) (P11) God exists. (P10, P3, modus ponens). Plantinga's Ontological Argument 1. A necessary proposition is defined as one that, if true, is true in all possible worlds. (definition of necessary propositions in modal logic) 2. God is defined as a maximally great being - meaning one that exists necessarily and is necessarily omniscient, omnipotent and perfectly good. (definition of God) 3. Possibly God exists. (Premise) 4. There is a possible world in which God does exists. (By 3) 5. Therefore, there is a possible world in which it is necessarily true that God exists. (By 2 and 4) 6. God exists in all possible worlds. (By 1 and 5) 7. Therefore, God exists. (By 6 and since necessarily true propositions are true) All that is left is to prove premise 3 from Plantinga and premise 4 from Hartshorne, but this follows from the fact that things that are logically possible are things that have no contradictions in their definition. So, for example, it is logically possible that if you pick a number between 1 and 10, the number is 5, which means that there is a possible world where the result is 5. In the same way, if God can logically exist, then there is a possible world in which he exists. To understand necessary and possible existence, picture a checkerboard. To say something possibly exists is to say that you put an X in one box where that thing exists (one possible world). To say something necessarily exists means that you must put an X in every single box (every possible world). If you agree that God is possible, meaning you can conceive of a being that is omniscient and omnipotent and cannot find a contradiction there, then there is a possible world where God exists, so put an X in one possible world. But since by definition God must necessarily exist, that means that if there is an X in one possible world, God must exist in all possible worlds. Because God either necessarily exists (exists in all possible worlds, with X's in each box) or necessarily does not exist (with no X's in any boxes). So once you've placed an X in one box, you know that it's not possible for God to necessarily not exist, so he must necessarily exist. Cosmological Argument 1. Something cannot come from nothing. 2. Whatever begins to exist has a cause. (from 1) 3. The universe began to exist. 4. The universe is infinite. 5. A finite entity cannot create an infinite entity. 6. God is infinite. 7. God caused the universe to exist. (from 6, 5, 4, 3 and 2) Teleological Argument There are certain constants in physics, like the value of the strong force, which if altered by even the tiniest fractional amount would create a completely unstable universe. All of these constants being in exactly the correct range is impossible, so some entity must have fine-tuned the numbers by design and that entity is God. The argument goes: "It was recognized centuries back that conditions necessary for the flourishing of life were fairly tightly constrained (making the move to design in natural conditions and laws inherently attractive), but not until quite recent times has it been revealed through science itself just how wildly tight the constraints actually are, and just how many separate things have to converge, each within a miniscule value interval. For instance, here are two examples taken from Robin Collins: 1. If the initial explosion of the big bang had differed in strength by as little as one part in 1060, the universe would have either quickly collapsed back on itself, or expanded too rapidly for stars to form. In either case, life would be impossible. (As John Jefferson Davis points out, an accuracy of one part in 1060 can be compared to firing a bullet at a one-inch target on the other side of the observable universe, twenty billion light years away, and hitting the target.) … 3. Calculations by Brandon Carter show that if gravity had been stronger or weaker by one part in 1040, then life-sustaining stars like the sun could not exist. This would most likely make life impossible. (Collins 1999, 49.)[37] In light of these and other examples, Collins remarks that "Almost everything about the basic structure of the universe … is balanced on a razor's edge for life to occur." (Collins 1999, 48). There is some disagreement over just how many such independent factors there are, but by some counts there are over 100, although not all requiring the above degree of precision.[38] But the apparent probability of all the necessary conditions sufficient to allow just the formation of planets (let alone life) coming together just by chance is utterly outrageously tiny—by Roger Penrose's calculation, the probability of chance alone producing cosmoi capable of producing planets is 1 in 10 raised in turn to the 10123 (Penrose 1990, 343–4)." http://plato.stanford.edu...