One of the more interesting arguments for the existence of God is the idea that you cannot argue without logic and without God there would be no logic. When a Christian uses this argument with an atheist, he concludes that God must exist or we couldn’t even be having this argument. This can end the debate quickly if the atheist is not ready with a counter argument.

This argument is based on the idea that there are three basic laws of logic. 

1. The logical law of identity says that something is itself. This seems pretty reasonable.
2. The logical law of non-contradiction say that a statement cannot be both true and not true at the same time. Again this seems reasonable.
3. The logical law of the excluded middle says that either a statement is true or the opposite is true. This is a little more problematic in a complex world.

Aristotle discussed these laws over 2000 years ago and they have been used ever since to reason about the world. The religious argument based on these laws of logic says that these laws are universal and not based on any particular thing at any time or place. Therefore they are transcendent. They are also concepts and concepts cannot exist without a mind to hold them. So transcendent concepts must exist in a transcendent mind and God is that transcendent mind.

There are several big leaps in an argument that is supposed to be based on a chain of reasoning. One problem is that there are different kinds of logic. Aristotle’s logic is well known but there are other types not as well known.

There is “fuzzy” logic that deals with “shades of grey”. Terms like “old” and “tall” are well defined sharply bounded ideas. But there are degrees of each of them. So instead of something being true OR false, it could be only 75% true, for example. Then there is the idea of a continuous range of possibilities. Atmospheric humidity is not “wet” or “dry”, it is somewhere in the range. So if you considered these qualities to be overlapping, then you could have the humidity be 25% wet and 75% dry. So much for the excluded middle and non-contradiction.

Another problem is the idea that logic is some kind of absolute ideal thing that stands outside of space and time. Logical statements must be presented in a language. Languages have complex differences. And languages are definitely dependent on minds that exist in time and space. While some of the things that exist beyond human beings can be reasoned about with a particular logic, those external things are not themselves logical entities that require a mind to exist.

Even if you were to grant the Christian that logic is a transcendent absolute that requires a God, you still do not have any reason to believe that that God is the Christian God. This requires a great leap of faith unconnected to the logical argument.

And finally, for good measure, there is the question of whether God is bound by logic. In other words, can God be himself and not himself at the same time? If he cannot, then he is not omnipotent.