Final answer:
Descartes would argue against Assumption 2 by stating that just because something is conceivable does not mean it is possible. He would point out the masked man fallacy, which occurs when we mistakenly assume that what we can imagine or conceive in our minds must be true or possible in reality.
Step-by-step explanation:
Descartes would reply to Assumption 2: What is conceivable is possible by arguing against it. Descartes would argue that just because something is conceivable does not necessarily mean it is possible.
He would propose that the masked man fallacy occurs when we mistakenly assume that what we can imagine or conceive in our minds must be true or possible in reality.
Descartes would assert that our ability to imagine or conceive something does not prove its existence or possibility in the external world.