Problems related to expertise are amongst the most pressing issues of our time. Although philosophical reflection has much to contribute to the identification and resolution of these problems, the topic of expertise has not received the professional attention that it deserves. Expertise: Philosophical Reflections corrects this imbalance by critically addressing fundamental conceptual and normative issues related to three topics: 1) the phenomenology of expertise, 2) interactional expertise, 3) the ethics and politics of expertise. In so doing, it covers a range of technological issues related to expert authority, judgment, and competence, including: the prospects of artificial intelligence, the ethics of sustainability research and sustainable design, controversy over advocacy for genetically modified foods, and behavior-modifying technologies called "nudges."