Philosophy in Review XXXV (2015), no. 1 Penelope Maddy. What do Philosophers Do? Skepticism and the Practice of Philosophy . Oxford University Press 2017. 264 pp. £19.99 GBP (Hardcover ISBN9780190618698 ). Probably every philosopher when confronted with this by an audience of non-philosophers will have noticed that most of the time the reaction is merely a compassionate smile. In the worst case his or her profession is mistaken with psychology and in the better case he or she will be asked about the meaning of life or, again with that same compassionate smile, the existence of the outside world. In her familiar lucid style Penelope Maddy takes us on a journey to formulate an answer to the question what it is what philosophers actually do, while at the same time dealing with the question why skeptical arguments about our knowledge of the outside world are a challenge any serious philosopher should at least take seriously. The book found its conception in the lectures given by Maddy during her Phi Beta KappaRomanell professorship in 2013-2014 and is written to serve a wide non-philosophical audience with an accessible book without giving in on rigor and depth. A task she completed in an outstanding manner. The main characters of the book are Plain Man, first introduced by and modeled to the image of the philosopher J.L. Austin, and Plain Inquirer who also appears in Maddy's earlier work under the name of the Second Philosopher. Together they respond to two skeptical arguments, Descartes' Dream Argument and Berkeley's Argument from Illusion. In two appendices of the book Maddy also gives some remarks on the Infinite Regress of Justification argument and the Closure Argument. In responding to these skeptical arguments five methods of doing philosophy are considered. Common-sense philosophy and ordinary language philosophy both attributed to Austin, Maddy's own austere version of naturalism better known as Second Philosophy, therapeutic philosophy as propagated by Wittgenstein, and finally conceptual analysis. Having said this it is clear that this book serves two different purposes. The first one is to respond to the before-mentioned skeptical challenges, the other one is to introduce the reader into metaphilosophy, the philosophy of philosophy, or in the case of this book, what Maddy considers to be the proper way to do philosophy. So how do we know that what we consider to be the outside world isn't just an elaborate dream, or how do we know that we are not a brain in a vat created by an evil scientist? If all we have to rely on is the information supplied to us by our senses, how can we tell that there really is an outside world behind these sensory inputs, or, if there is indeed an outside world, how can we tell that this world resembles the picture we have of it given these sensory inputs? It are questions like these that the skeptic denies we can answer. According to the skeptic we have as much reason to believe for instance that we have hands and that there is a chair in front of us as we have reasons to disbelieve them. After careful consideration of the skeptic's arguments we learn that it is Maddy's conclusion that in the end these arguments form no danger for our ordinary beliefs about the outside world and also form no danger to the ways in which we usually acquire these beliefs. Now how does she come to these conclusions? The first skeptical challenge Maddy discusses is the Dream Argument. With its origin in Descartes Meditations on First Philosophy. This argument is basically the thought that the example of what we experience while dreaming supplies us with evidence that our senses are not the be trusted when it comes to distinguishing between waking and dreaming or between reality and illusion. The conclusion is that any one of our beliefs that is dependent on sensory input should at the very least be carefully examined to determine whether it is in fact real or illusory. Since sensory inputs are also the starting point for the beliefs of both Plain persons they might find themselves in trouble here. Employing his Method of Doubt Descartes hopes to find principles that are more certain than the evidence from his senses. The Plain Inquirer will in principle agree here with Philosophy in Review XXXV (2015), no. 1 Descartes although not wholeheartedly, especially when it comes to his conclusions. Her response will be that of course she is willing to admit that her beliefs can have sources of error in them and of course she is more than willing to adjust her beliefs given new evidence to do so. What is more important is that in the end neither Descartes nor the Plain Inquirer draw any skeptical conclusion. Descartes believes he has found the certain principles he was looking for and the Plain Inquirer, although not convinced by these certain principles, goes on using the methods she learned to rely on in supplying her with her beliefs. When the original Dream Argument is extended from ordinary dreaming to extraordinary dreaming, this is the sort of dreaming where the distinction between dreaming and waking cannot in principle be made because extraordinary dreaming is an allencompassing continues dream, the challenge gets harder. After careful consideration Maddy however concludes that the concept of knowledge we employ by no means demands that the option of extraordinary dreaming is ruled out and thus no skeptical challenge arises. To go a step further Maddy also argues that even if it were the case than we are unable to know or to acquire knowledge it isn't at all clear how extraordinary dreaming implies that all of our beliefs are just as likely true as not true. The Argument from Illusion, that can be found among others in Berkely, Russell and Ayer, find its origin in the fact that things are not always as they seem to be. To be more specific it is an argument about the existence of sense-data. If a stick is held underwater it seems to be bend and no longer the straight stick that it was before it was held underwater. Despite knowing that the stick is straight the mental image we have is that of a bend stick. Since the stick is not in fact bend this mental image of a bend stick is described as an illusion. What is actually perceived is not a direct image of the stick as it is but an indirect image or sense-datum. This being the case the skeptical conclusion from this argument is easily made. If all there is to perceive is sense-data than the belief that the stick is straight before held underwater is just as likely to be false as the belief that it is bend after holding it under water. Being mediated by sense-data any knowledge about the stick, or of whatever what, is an impossibility. Based among others on theories on vision Maddy makes a convincing case that the sense-datum inference on which the Argument from Illusion is based is wrong and that, even if it were not, the step to the skeptical conclusion drawn from it is one that can't be made. In order to justify the step from a representative theory of perception to its skeptical conclusion perception itself has to be justified in terms of other faculties. A step that Maddy rejects as being an unmotivated inference from inner to outer. One of the questions this book tries to answer is that why, despite all the arguments against it, the skeptical 'from scratch' challenge is taken to be so dangerous to our ordinary beliefs that it is insisted it should be ruled out. G.E. Moore thinks it is because philosopher tend to underestimate common sense, Wittgenstein because he thinks that skepticism as well as anti-skepticism are two different language games each with their own rules. The Plain Inquirer and Maddy with him admit that they can't meet the extreme 'from scratch' challenge to rule out skepticism but they still hold their conviction that given all the methods they have come to rely they have no reason whatsoever to doubt any of their beliefs or be that of Plain Man. The different skeptical challenges are shown to be based solely on 'argumentative slips, verbal distortions, anachronistic theorising, unmotivated presuppositions, and plain acts of inattention and carelessness'(201). Returning now to the initial questions of what it is what philosophers do and what the proper method of doing philosophy is. Maddy concludes that there are plenty of genuine philosophical questions to be answered. About the proper method of answering these question she agrees with the Plain Man and the Plain Inquirer that employing common sense and ordinary empirical methods are the right way to follow. Where possible and useful these can be supplemented by conceptual analysis, therapeutic philosophy, and ordinary language philosophy. Philosophy in Review XXXV (2015), no. 1 To write a book for non-philosophers about what it is exactly that philosophers do, is by no means easy. Still, Maddy has succeeded very well with this book. It is very well written and not at all difficult to understand for a non-philosophical audience. It is an invitation to the reader to delve deeper into the fascinating world of philosophy and metaphilosophy. Jan Arreman, Independent Scholar