This volume presents, develops, and champions contextualist solutions to two of the stickiest problems in epistemology: The puzzles of skeptical hypotheses and of lotteries. It is argued that, at least by ordinary standards for knowledge, we do know that skeptical hypotheses are false, and that we've lost the lottery (unless one is in fact the winner of the lottery, in which case one does not know that one has lost, but is reasonable in thinking that one knows it). Accounting for how it is that we know that skeptical hypotheses are false and why it seems that we don't know that they're false tells us a lot, both about what knowledge is and how knowledge attributions work. Along the way, the following are all carefully explained and defended: Moorean methodological approaches to skepticism, on which one seeks to defeat, rather than refute, the skeptic; contextualist responses to skepticism; contextualist substantive Mooreanism; the basic safety approach to knowledge and the double-safety picture of what knowledge is; insensitivity accounts of various appearances of ignorance; the closure principle for knowledge and the claim that our knowledge that we are not brains in vats is a priori, despite its being knowledge of a deeply contingent fact. © Keith DeRose 2017. All rights reserved.