Descartes point of view during the argument

So, if I was Descartes, arguing against Hume, I would have hammered home my method of doubt even more, turning Hume's favorite question, "How do you know?" back on Hume. I would have said, there is no way to know anything for sure, thus, you must doubt anything. "How do you know?" - I am a thinking substance, but all your senses can deceive you, you don't know ANYTHING for certain. Using your inductive reasoning, you can only make uncertain knowledge, only form assumptions about anything. There is no deductive reasoning, no certainty anywhere. Lastly, Hume's statement, "Reason is the slave of the passions" is ludicrous, because there is no pure passion, there is only logical and rational reasoning, which comes first and foremost before all emotions.