This book explores the issue of (un)explainable technology. As we face technologies, mostly autonomous, machine-learned algorithms (AI) that elude a seamless explanation on how they work (“black boxes”), several issues both from an epistemological as well as ethical perspectives emerge. It is thus not surprising that there are plenty of technological attempts in illuminating the black box as well as philosophical efforts in conceptualizing and re- assessing our concepts of an explanation and understanding, as well emerging ethical questions on how to deal with this unexplainable technology. This book thus offers a succinct and comprehensive, opinionated but fair view on the emerging ethical debate on explainability of AI and its relevance for using AI for different more or less sensitive decision-making procedures. As a short book, the goal is to introduce the reader to the issues at hand while also offering normative arguments from different sides that motivate, complicate, and resolve these issues.