Pascal’s Wager is an argument for belief in God based not on an appeal to evidence that God exists but rather based on an appeal to self-interest. It is in our interests to believe in God, the argument suggests, and it is therefore rational for us to do so.
The claim that it is in our interests to believe in God is supported by a consideration of the possible consequences of belief and unbelief. If we believe in God, the argument runs, then if he exists then we will receive an infinite reward in heaven while if he does not then we have lost little or nothing.
If we do not believe in God, the argument continues, then if he exists then we will receive an infinite punishment in hell while he does not then we will have gained little or nothing.
Either receiving an infinite reward in heaven or losing little or nothing is clearly preferable to either receiving an infinite punishment in hell or gaining little or nothing. It is therefore in our interests, and so rational, to believe in God.
The Ontological Argument
The ontological argument is an argument that attempts to prove the existence of God through abstract reasoning alone. The argument begins with an explication of the concept of God. Part of what we mean when we speak of “God” is “perfect being”; that is what the word “God” means. A God that exists, of course, is better than a God that doesn‘t. To speak of God as a perfect being is therefore to imply that he exists. If God’s perfection is a part of the concept of God, though, and if God’s perfection implies God’s existence, then God’s existence is implied by the concept of God. When we speak of “God” we cannot but speak of a being that exists. To say that God does not exist is to contradict oneself; it is literally to speak nonsense.
The Cosmological Argument
The cosmological argument is the argument from the existence of the world or universe to the existence of a being that brought it into and keeps it in existence. It comes in two forms, one modal (having to do with possibility and the other temporal (having to do with time).
The modal cosmological argument, the argument from contingency, suggests that because the universe might not have existed (i.e. is contingent), we need some explanation of why it does. Whereever there are two possibilities, it suggests, something must determine which of those possibilities is realised. As the universe is contingent, then, there must be some reason for its existence; it must have a cause. In fact, the only kind of being whose existence requires no explanation is a necessary being, a being that could not have failed to exist. The ultimate cause of everything must therefore be a necessary being, such as God.
The temporal kalam cosmological argument, begins by arguing that the past is finite. The idea that the universe has an infinite past stretching back in time into infinity is, the argument notes, both philosophically and scientifically problematic; all indications are that there is a point in time at which the universe began to exist. This beginning must either have been caused or uncaused. It cannot have been uncaused, though, for the idea of an uncaused event is absurd; nothing comes from nothing. The universe must therefore have been brought into existence by something outside it. The kalam argument thus confirms one element of Christianity, the doctrine of Creation.
The Teleological Argument
The teleological argument is the argument from the order in the world to the existence of a being that created it with a specific purpose in mind. The universe is a highly complex system. The scale of the universe alone is astounding, and the natural laws that govern it perplex scientists still after generations of study. It is also, however, a highly ordered system; it serves a purpose. The world provides exactly the right conditions for the development and sustenance of life, and life is a valuable thing. That this is so is remarkable; there are numerous ways in which the universe might have been different, and the vast majority of possible universes would not have supported life. To say that the universe is so ordered by chance is therefore unsatisfactory as an explanation of the appearance of design around us. It is far more plausible, and far more probable, that the universe is the way it is because it was created by God with life in mind.