Many philosophers will recognize David Edmonds as one of the voices of Philosophy Bites, a popular podcast that engages with a variety of different philosophical topics.  However, Edmonds is also an expert in the sub-field that has come to be known as “trolleyology.”  This somewhat derisive term refers to an interdisciplinary field of study that seeks to utilize intuitive responses to various moral dilemmas to identify substantive moral principles and draw conclusions about human moral psychology.  Edmonds does an outstanding job of introducing the reader to the historical emergence and subsequent development of trolleyology, explaining its significance for both moral philosophy and moral psychology, and responding to a number of substantive criticisms of the field.  Edmonds’s expertise is clearly on display throughout the text, and he largely succeeds in producing a work that is informative and sophisticated without being overly technical. 

While this book is appropriate for Edmonds’s stated target audience of “someone who does not have a PhD in philosophy,” his discussion would likely be difficult to follow for someone with only limited experience with significant philosophical works.  It is a feature of Edmonds’s work that he draws numerous connections between trolleyology and a variety of significant philosophical ideas and debates.  But this feature is also something of a bug; Edmonds spends very little time clarifying what these ideas and debates are about, and one gets the sense that Edmonds takes the reader’s familiarity with these notions for granted. 

Edmonds begins by introducing the reader to the original trolley problem, known among trolleyologists as Spur.  Spur consists of an ethical dilemma where one must choose between allowing an out-of-control trolley to kill five innocent people, and pulling a lever that redirects the trolley onto another track where only one person will be killed.  An especially attractive feature of Edmonds’s discussion of the development of Spur is his inclusion of relevant social and historical factors regarding its creator, Philippa Foot.  These factors provide an immediate sense that trolley problems can be informative for resolving real-life moral problems, despite their abstract nature.  This point is made more convincing by Edmonds’s discussion of numerous historical examples that are roughly equivalent to the sort of decision one must make in Spur.   

Spur is contrasted with a similar scenario, known crassly among trolleyologists as Fat Man.  Fat Man is just like Spur, except that instead of pulling a lever to redirect the trolley and save the five, one must push a very fat man off of a footbridge above the track.  His massive girth, it is stated, will stop the trolley, but kill him in the process.  When presented with these cases, most people conclude that it is morally permissible to flip the lever in Spur, but morally wrong to push the Fat Man. 

What to make of these results is the focus of the remainder of the first section of the book.  For consequentialists, who regard the morally right action as the one with the best balance of good versus bad consequences overall, these results are potentially problematic, since they suggest that for most people, consequences are not the only thing that matter morally.  For deontologists, who regard the morally right action as a matter of doing one’s moral duty whatever the consequences, things are more complicated.  Deontologists who affirm that we should pull the lever, but not push the Fat Man must identify some moral principle which accounts for our differing moral obligations in each case. 

Articulating this moral principle, notes Edmonds, led to an explosion of variations on both Spur and Fat Man.  Increasingly elaborate trolley problem were concocted, involving additional pulls of the lever, lazy Susan’s, extra sections of track, and runaway tractors.  At this point, the claim that trolley problems are informative for both moral philosophy and real-life moral dilemmas becomes less compelling.  While Spur and Fat Man seem clearly relevant for both moral philosophy and moral psychology, cases like Two Loop and The Tumble are so bizarre that it’s difficult to form any clear moral intuitions about them, never mind identifying their broader moral significance.  As a result, Edmonds’s claim that trolleyology is informative despite its abstract nature is only somewhat convincing. 

This is reflected in the psychological and experimental literature discussed in the second section of the book.  Edmonds makes a concerted effort to explain and identify numerous empirical studies that utilize trolley-type scenarios.  Nearly all of these studies utilize some version of Spur or Fat Man; the other trolley scenarios rarely make an appearance.  Further, Edmonds tends to draw conclusions from this research that are overly ambitious and not well-supported by the given data, such as his claim that empirical data on the disparity in responses to Spur versus Fat Man indicates that the Doctrine of Double-Effect is part of an innate moral sense, comparable to our innate linguistic capacities.  So while Edmonds makes a compelling case for the usefulness of trolley-type scenarios for empirical moral psychology, Edmonds draws bold conclusions from this data that are not sufficiently supported by the evidence given here.

Overall, this book is an informative, socially and historically well-situated introduction to trolleyology, as it pertains to both moral philosophy and empirical moral psychology.  It also offers the concerned reader a good, but not fully convincing defense of some of the most serious criticisms of trolleyology.  However, the reader is left with an unclear sense of the usefulness of trolleyology beyond Spur and Fat Man.  While there is clearly something both philosophically and psychologically interesting about the way people respond to these cases, one gets the sense that the other versions of the trolley scenario are less a tool for better understanding morality, and more the sort of “exercise in cleverness” that plagues certain areas of philosophical discourse.

© 2014 Eli Weber

Eli Weber is a graduate student in the Philosophy Department at Bowling Green State University.  He specializes in ethics, applied ethics, and philosophy of the emotions.