René Descartes was a famous philosopher who coined the classic phrase, “I think, therefore I am.” When Descartes came up with that idea he believed that he had dumped all of his knowledge base and was essentially starting from scratch to determine what man could truly know based on his reason alone. The only way to be free from doubt was to start at ground zero and work from there. Well, it’s my belief that Descartes did not get too far before he messed up. More accurately his logic failed in his first statement. Three cheers for human reason!
Why did Descartes fail? Doesn’t the ability to think in a self-aware fashion prove that “one is”? Not so fast. Remember Descartes was trying to prove this without establishing belief. He was seeking to create an epistemological foundation on which to build all of his other thoughts. Yet without a provable foundation his other thoughts are suspect.
So why is the idea “I think, therefore I am” a statement of belief that goes beyond what human reason is able to demonstratively prove from a strictly rationalistic perspective? Descartes’ logic is as follows: “I doubt, therefore I think, therefore I am.” Yet, with this idea he has actually proven his inability to perform a true epistemological dump and has started with a presuppositional idea of “I” or “self.” Who does the doubting? He does. But then how can he be sure that he is anything at all before coming to that conclusion? He cannot establish or prove the idea of self with this method, despite his attempt. There are other ideas within the realm of a strict rationalistic plausibility structure that could account for his thinking that would result in a statement that defeats his idea of a “self” or, at the very least, “his self” doing the thinking.
Just because one is thinking does not demonstratively prove that one is the agent responsible for ones thoughts. (Let that thought bake your noodle) Again from a strong form of rationalism one could argue that the idea of a self could technically be a projection of a foreign agents manipulations that have created a manifestation of a self that is not in actuality a true and free self thinking agent.
Finally, even if we were to look past this major flaw, his logic also fails to provide necessary proof for what thought is. How can you establish self prior to establishing thought? How can you establish thought without a self? It is yet again a statement of belief. He is assuming rationality behind his thoughts, despite his doubts, and then declaring existence based on that unproven concept of thought. You cannot make a declaration of what something is when based on your ability to think if you have yet to establish a grounds for proving that your thoughts are even anything coherent.
No matter what you do, no matter how many times you start with human reason alone, you cannot escape the less poplar idea of philosopher Alvin Plantinga that “All knowledge rests on belief.” To declare that we know anything, even that “I am” or even more that “I doubt”, is to believe in something. The irony of this is that many people argue that it is wrong to believe in God unless you can demonstratively prove His existence, yet they themselves certainly have beliefs and when it comes down to the nitty gritty reality of human epistemology nothing can be proved in the way that these philosophers demand. To be consistent with that same standard about belief in God they have no right to believe in their own thoughts, their own existence, their own beliefs nor their own lack of belief. By reason alone they cannot establish a shred of “knowledge” that could ever be holistically and demonstratively proven and ironically they could therefore never systematically prove that something, anything really, was not true. If you have zero knowledge about what is, you have zero knowledge about what is not. You are always one fact away from finding out that 1+1 is not what you think it is, you cannot perfectly, systematically, and rationalistically even prove that to the level of absolute. There are other possibilities. Anyone starting to smell a little post-modernity? Indeed, how great the darkness. (Colossians 1:13-14, John 1:5)
Does this prove God’s existence? Of course not. Does this prove a glaring lack of consistency on the part of many? I believe that it does. Another irony is that this lack of “knowledge” is not a defeater for Christianity but a declaration of its own testimony. “My message and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and power, so that your faith would not rest on the wisdom of men, but on the power of God.” (I Corinthians 2:4-5, cf. I Cor. 1:17-31) It would be more problematic for Christianity if this level of knowledge and provability were required by it, the fact that it testifies against such an establishment of knowledge is more of a sign post towards it than it is an easy defeater of it.
(I’ve written a bit more on this topic in: The Knowledge Problem within a Secular Worldview)