Suppose you can stop a trolley from killing five people, but only by turning it onto a side track where it will kill one. May you turn the trolley? What if the only way to rescue the five is to topple a bystander in front of the trolley so that his body stops it but he dies? May you use a device to stop the trolley that will kill a bystander as a side effect? The "trolley problem" challenges us to explain and justify our different intuitive judgments about these and related cases. Frances Kamm's 2013 Tanner Lectures present some of her views on this notorious moral conundrum. After providing a brief history of changing views of what the problem is about and attempts to solve it, she focuses on two prominent issues: Does who turns the trolley and how the harm is shifted affect the moral permissibility of acting? The answers to these questions lead to general proposals about when we may and may not harm some to help others. Three distinguished philosophers - Judith Jarvis Thomson (one of the originators of the trolley problem), Thomas Hurka, and Shelly Kagan - then comment on Kamm's proposals. She responds to each comment at length, providing an exceptionally rich elaboration and defense of her views. This book is invaluable not only to philosophers concerned about the trolley problem, but to anyone worried about how we ought to act when we can lessen harm to some by harming others and how we can reach a decision about the question.

"subtle, brilliant ... Kamm's forte lies [in] the illuminating new perspectives and puzzles she opens up." - Jane O'Grady, Times Higher Education

"In response to her commentators Kamm tries to answer these objections and many other objections. And these remarkable exchanges between some leading contributors make this book really invaluable. I suggest reading this book to every graduate student or moral philosopher who wishes to know lots of hypothetical cases in which the trolley problem happens." - Ebrahim Azadegan, Metapsychology Online Reviews

"... the book is best seen as an overview of the important contributions that Kamm and her interlocutors have made to the literature. It is also a rich source of cases for testing new hypotheses -- cases ranging from ingenious classics like Transplant, Driver, and Bystander, to some newer developments like Driver Topple and Thomsonâs Loop Case, to some particularly perplexing cases involving tractors and bombs ... the trolley problem is still as real, pressing, and fascinating as ever, and it is helpful to have as oneâs guide through the problem a philosopher who does not shy away from complexities." - Molly Gardiner, Ethics

"Professor Frances Myrna Kamm, a moral philosopher who for decades has been a leading analyst of this thought experiment, has now published her richly stimulating Tanner Lectures. Joining her lectures as chapters in the book are a trio of rigorous and unrelenting responses from a panel of philosophersProfessors Judith Jarvis Thomson, Thomas Hurka, and Shelly Kaganas well as an introduction by legal scholar Professor Eric RakowskiThe beating heart of this book is a fresh, often raw, analytical quarrel between Kamm and ThomsonThe books timing is impeccabledue in part to its uncanny resemblance to emergent questions about how to program autonomous vehiclessuch as military drones or driverless carsto act ethically." - Harvard Law Review