 Dretske and Nozick focused on a form of skepticism that combines K with the assumption that we do not know that skeptical hypotheses are false. For example, I do not know not-biv: I am not a brain in a vat on a planet far from earth being deceiving by alien scientists. On the strength of these assumptions, skeptics argue that we do not know all sorts of commonsense claims that entail the falsity of skeptical hypotheses. For example, since not-biv is entailed by h, I am in San Antonio, skeptics may argue as follows: