Well, it proves self existence (which was a genuine point of interest in the early Enlightenment). There's no way to prove it to another though, sadly.

[quote]Well, it proves self existence[/quote]No, it doesn't actually. You see, the 'I' that is apparently proven to exist at the end, is already there at the start. 'I think' already presupposes that I exist, so it cannot therefore be proof that I exist. How do i know i exist? Because I am thinking. But how do I know I am thinking? Because I exist. It's a classic example of circular logic. It's like saying the Bible is true because it is the word of God, and God exists because it says so in the Bible.

Circular logic can actually be applied to these circumstances though. How can you exist without the capability to do anything? Doing something proves the point of existence, as existing proves the point of being able to do something.