As one of the original thinkers behind probability theory, Blaise Pascal developed what is commonly referred to as "Pascal's Wager" in an attempt to prove by deductive reasoning that believing in a higher power was more rational than not. He did not strive to convince that God in fact does exist, but rather the probability that there is a God is great enough that it would be foolish for one not to believe. In doing this Pascal was not able to develop a theory that applied universally to religion, but instead created a dichotomy between those who believe in a Christian God, and those who do not. For this reason "Pascal's Wager" better served as a defense of Christianity and as a justification of the Christian faith.
The Wager initially establishes that it is not necessary to prove that God exists for him to actually exist. Pascal likens this to the number infinity. He states that although we do not know what the number infinity is, we are well aware that numbers are not finite. In knowing that numbers are not finite we are able to gather an understanding that there is an infinite number, whatever that may be. By the same method of proving infinity he claims that, "therefore we may well know that God exists without knowing what he is." Since Pascal acknowledges that he, or anyone else, cannot legitimately prove that there is a God he resorts to defending the choice that Christians have made by saying "who then will condemn Christians for being unable to give rational grounds for their belief." Calling into question the use of reason in explaining God, for the first time in his Wager, further defends this. He asserts that reason cannot decide if there is or is not a God because "reason cannot make you choose either, reason cannot prove either wrong." This is later contradicted when Pascal goes on to explain the Wager.
The main premise of "Pascal's Wager" revolves around the idea that there are two choices that can be made pertaining to whether or not there is a God, and that everyone must wager one of the two ways.