In the passage from Descartes’ Meditation, the conclusion is that Descartes now has reason to doubt all of his beliefs including those of his senses. The premises seem to be: (1) If an omnibenevolent god wouldn’t deceive us then there must be an evil demon doing so. (2) If an evil demon is our source of deception then one cannot know true beliefs. In the passage from Sweetman’s “The Pseudo-Problem of Skepticism” the conclusion is that we should not take the problem of skepticism seriously because we have no reasons to do so. The premises seem to be: (1) We know that it is not possible to be a brain in a vat. (2) If we know that it is not possible, then we have no good reason to believe that we are just brains in vats. In the passage from
