What is the response to the quote "I think therefore I am"?

Question

Another philosopher retorted this quote by Descartes but I can't remember how it went and who said it. It said something about being the consciousness behind the thought. This is killing me that I can't find it....

Answer 1

"I think I am, therefore, I am. I think." - George Carlin

or

Maybe something said by Immanuel Kant [not sure of an exact quote]. I know he had some problems with the Descartes' statement.

Answer 2

i know i exist because i can think. by descartes

Answer 3

Cogito Ergo Sum.... I think it was said to by Plato and/or Aristotle.... But I am not very sure of it... n_n