Why should one make an argument for the existence of God? Why, moreover, provide five of them? Is it that the evidence for God is so weak, that believers need multiple arguments, working together in their persuasive power, to change the minds of unbelievers? Questions of whether or not these arguments are useful, or if they can actually coerce religious belief has been an area of interesting debate between philosophers for some time now.
In philosopher Alvin Plantinga’s essay “Twenty Dozen (or so) Theistic Arguments” (1986), he firsts asks this question: “What are these arguments like, and what role do they play?”  Plantinga answers this question by saying that these arguments are probabilistic either with respect to (1) the premises, (2) the connection of the premises with the conclusion, or (3) both. Furthermore, “[t]hey can serve to bolster and confirm. . . perhaps to convince” . Of course, Plantinga is careful with what it means for these arguments to be coercive. As he writes, “These arguments are not coercive in the sense that every person is obliged to accept their premises on the pain of irrationality. Maybe just that some or many sensible people do accept their premises (oneself)” . And so, the discussion could go on.
However, I present five arguments here for the existence of God so that I might establish a cumulative case for his existence. This is because some arguments are more so about strong probability (i.e.,the argument from religious experience, argument from miracles, etc.) while others can have a demonstrative element to them (i.e., Aquinas’ Third Way). The combination of these given characteristics can (in my opinion) be very effective in a case for theism – particularly, that of Christian theism. These arguments are as follows:
- (I) The Kalam Cosmological Argument
This argument draws from several lines of evidences (mathematics, science, philosophy) that try to connect the premises with its conclusion – namely, that the universe has a cause of its existence. The argument can be summarized as such: The universe cannot have existed forever in the past. In other words, the universe cannot be past-eternal. Why not? We have reached the present moment. If the universe were past-eternal, we would never reach “the present moment”; an infinite amount of “moments” would have to be realized before we reached the “present moment” (which is absurd). Therefore, the universe must be finite. If the universe is finite (i.e., began to exist), then the universe requires a cause (totally separate from it) to bring it into existence.
This cause must transcend space and time – because it created space and time – and therefore must be timeless and immaterial. But, we ask, what sorts of things that are immaterial and timeless, cause things to exist? We only have two options: (1) Abstract objects or (2) a transcendent Mind. By (1) I simply mean something like a number, but of course abstract objects can’t cause anything to exist (the number 7 has no causal power). Therefore, this cause must be a Mind – which is what believers understand to be God.
- (II) Leibnizian Cosmological Argument
Whatever exists has an explanation of its existence. In other words, nothing exists without a reason accounting for that thing’s existence. However, there are two kinds of existence that we have to be clear about: (1) necessary existence and (2) contingent existence. If something necessarily exists, then the explanation of its existence is within itself, not outside of itself.
Philosophers have argued that numbers, properties, and even the laws of logic are all necessarily existent – in the sense that none of these came into existence by some other thing, but rather that they exist by the necessity of their own nature. However, if something is contingently existent, then the reason for its existence is external to it – you and I are contingent, and so is the computer that you are using. The shortcut understanding is this: contingent things have the possibility of existing or not existing, necessary things either must or must not exist. With that understood, the argument is as follows:
- Everything that exists has an explanation of its existence.
- If the universe has an explanation of its existence, that explanation is God.
- The universe exists.
- Therefore, the universe has an explanation of its existence.
- Therefore, the explanation of the existence of the universe is God.
Given our terms above, let us restate (1): “Everything that exists has an explanation of its existence, either in the necessity of its own nature or in an external cause.” Why doesn’t God have an explanation of his existence, if he exists? or, otherwise stated, who created God? God is a necessarily existent being; he requires no external cause to bring about His existence. God is – and he cannot not be.
- (III) The Ontological Argument
First, suppose that we were to define God as “the greatest conceivable being” (GCB). Now, let’s assume that GCB only exists in your mind but not in reality. However, isn’t it true that existence in reality is greater than existence in just your mind? A mere idea of $100 in your pocket is far more lacking in being than a real $100 in your pocket. Thus, we have the assumption: GCB only exists in your mind. But, existence in reality is greater than existence in the mind. Therefore, GCB must exist in reality as well as in your mind (or else it wouldn’t be the greatest conceivable being). Therefore, the very idea of God suggests that He exists.
- (IV) The Argument from the Origin of the Idea of God
This argument has a close friendship with the ontological argument discussed above. Rather than suggesting that real being is associated with the content of the idea of God, another philosopher (René Descartes) is saying that God is such an idea that he must be the cause or the origin of this idea. The argument runs something like this: (1) We have ideas of many things; we have ideas of things that are real (the earth, the sky, etc.), but we also have ideas of things that appear to be innate. As Descartes writes, “Among these ideas, some appear to me to be innate, some adventitious, and some produced by me. For I understand what a thing is, what truth is, what thought is, and I appear to have derived this exclusively from my very own nature” .
Descartes thence goes on to have a very tedious discussion about these ideas, but what is important to notice is the next step to his argument: “All that remains for me to ask is how I received this idea of God. For I did not draw it from the senses; it never came upon me unexpectedly, as is usually the case with ideas of sensible things when these things present themselves. . . to the external organs” . Descartes contends that God is the source of the idea he has of God. He finishes: “[T]he mere fact that God created me makes it highly plausible that I have somehow been made in his image and likeness, and that I perceive his likeness, in which the idea of God is contained, by means of the same faculty by which I perceive myself” .
- (V) The Argument from Design
We notice that certain things according to our experience have been designed – or, displays a mark of intelligibility. For instance, the house requires a builder, the watch requires a watchmaker, and so on. However, what about the universe? We notice that houses and even watches have properties such as “the adjustment of parts into a whole” and “curious adapting of means to ends.” It is the case that the universe has these properties as well. If the universe does have these properties, then we can say that it is probable that the universe was also produced by design. We can put the argument like this:
- The universe displays design within the created order.
- Either this intelligible order is the product of chance or of intelligent design.
- Not chance.
- Therefore, the universe is the product of intelligent design.
- Design only comes from a mind, a designer.
- Therefore, the universe is the product of an intelligent designer.
-  From Alvin Plantinga, ed. Deane-Peter Baker (Cambridge University Press: 2007) p. 210
-  Ibid.
-  Ibid.
-  René Descartes, Philosophical Essays and Correspondence (Hackett Publishing: 2000) p. 114
-  Ibid., p. 121
-  Ibid.