Most people believe that God does exist. In a survey of Americans in 2006, 94% said that they believed in the existence of God. However, it is unlikely that these people have an argument for God’s existence. It is also unlikely that they know much at all about what God is like. In the medieval period, the philosopher-theologian Aquinas dealt with this problem by expanding an argument for God’s existence given by Aristotle. He turned one argument for God’s existence in five arguments later known as the five ways.
Aristotle offered a single argument for the existence of God in book 12 of the Metaphysics. He claimed that God was living, eternal, knowing and goodness. He argued for this position after he had established his entire metaphysics. He argued that change itself required an explanation. His argument was rather advanced considering that he was the first person to offer that kind of argument. Much later on, Aquinas recorded a summary of the various arguments of his time that proved God’s existence. He gave five such arguments. These became known as the five ways.
Today, popular understanding of the five ways is inaccurate. Aquinas did not defend the five ways in detail, but only offered summaries of them. He wrote these summaries using the technical Aristotelian vocabulary of his time. This would not be a problem if everyone studied Aristotle in school, but most do not. Dawkins, Richard Swinburne, Hume and Kant all criticized these arguments by destroying a position that Aquinas did not believe in. Among these people, Dawkins is the least reliable and is philosophically recognized as a perfect example of bad philosophy. So the best way to begin any understanding of the five ways is by carefully examining what Aquinas said that what Aristotle said in his metaphysics.
The five ways are five separate arguments that have three things in common. First, they all begin with some undeniable empirical fact. For example, there is some kind of change somewhere in the universe. People are born, crops grow, planets move and many other changes happen. Second, there is a reason for everything that happens in the universe. This does not rule out coincidence. What it does say is that all change and all things capable of change have reasons for their change or capability of change. To suggest otherwise is to block the progress of science. It is also irrational. Third, all of the arguments take us from the start to the finish by deductive reasoning. This is the strongest form of reasoning it is possible to have.
The five ways each compare a different but obvious aspect of our world to arrive at God’s existence. The first way argues from the capability of change that things have. The second way argues from cause and effect. The third way argues from the fact that some things exist that could have not existed. The fourth way argues from the fact that some things are better than others. The fifth way argues from patterns in nature – natural laws. This extremely brief summary should be enough to give a general idea of what sort of starting place the five ways have. Aquinas believes that they all succeed. As far as I am aware, no philosopher who has actually understood the five ways has succeeded in refuting them. Or in clearer terms, I am aware of no philosopher who has dialectically argued against the five ways and been successful. If that is true, then atheism can be and was proven false over 600 years ago.