That's true, Descartes had to deny (to question) its own existence, going to the limits of skepticism, to finnaly accept it by realizing that thinking must be an attribute of an existing being. Questionable? Maybe. At the end can one trully understand what reality is?

>>>Interesting question. I would say philosophical. :)
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>>Yes, the object in question might say: "Cogito ergo sum!" :)
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>Or, as we like to say in the Skeptics Society "Sum ergo Cogito" http://www.skeptic.com/