How do you make it to prove that you are there? Actually you can all doubt. All.

You can doubt all you can think. You can doubt even yourself. You can all call illusion and you can doubt even doubting. Got it?

The only thing that lasts is - you doubt. This was the track Rene Descartes was following. He found himself doubting.

And doubting was to him a sign of conscience. Doubting gave him evidence that he was thinking.

And he said his famous sentence: Cogito ergo sum - I think, therefore I am. Thinking was the proof that he is there.

Now Descartes goes a step further. We can all doubt, but in us there are thoughts of the perfect, of God he said. But where do these thoughts come from?

Humans are not perfect, for they doubt. And they have desires which they would not have if there would be perfectibility.

But there are thoughts of the perfect and of God. They can not come from other humansm because they are imperfect.

Descartes concludes that it must come from God, because he is the source of perfection and perfectibility. Thus Descartes came from doubting via thinking to God.

Well, the rest of finding arguments against Descartes I`ll leave to you. I only say to you that Descartes made a basic mistake. He was not able to see the world around him part of himself. He saw the world outside as object.

Nevertheless I love the Frenchman very much. He died at 64, and some say he got murdered by poison...