But are evil acts really an entirely distinct species of immorality? If so, what makes them different? Critics of the concept of evil might also wonder whether such talk has a proper place in contemporary moral thinking. Is evil, in reality, a theological concept that makes little sense in a secular context?

In Being Evil, Luke Russell, a philosopher at the University of Sydney, develops a non-religious theory of evil acts and evil persons which he hopes is acceptable to a secular audience as well as to those who believe in supernatural beings. In the book – which is a model of how to communicate complex ideas to a general audience – Russell defends the idea of evil as a relevant explanatory category that provides insight into our contemporary world.

A key challenge for Russell in developing his secular account of evil is to provide plausible responses to what we might call ‘evil scepticism’. The first of these sceptical challenges questions whether there is something fundamentally or radically different about evil acts and evil people. It is a form of scepticism neatly captured in Tom Waits’s 1980 tune ‘Heartattack and Vine’ when the bar-room philosopher sings ‘don’t you know there ain’t no devil, there’s just god when he’s drunk’. In a similar vein, one might think that evil acts are simply more extreme versions of everyday wrongdoing. This is certainly the line that sceptics such as the philosopher Phillip Cole pursue. Cole also claims that nothing can be explained by appeals to evil personhood: it is not that he does not believe in right and wrong, but he doubts that evil is a distinct category.

What is it, then, that distinguishes evil acts from the merely very very bad?  Russell considers a wide range of possible accounts – such as those based on the malice, or the level of harm inflicted or the horror-worthy nature of the acts – that have been developed in recent years by philosophers and literary theorists. Russell rejects accounts that focus on the sadistic intent of the perpetrator in favour of those focused on the harm caused. He suggests that an act is evil if and only if it is a wrong that is extremely harmful for at least one individual where the wrongdoer is fully to blame for the harm. The account clearly captures a significant way in which people act badly: the question for the reader is whether this is sufficiently different in kind to be regarded as a separate species of wrongdoing.

The second sceptical criticism – which many readers will probably find more compelling – is that talk of evil is morally damaging and dangerous. It is not just that evil does not exist but that we do harm thinking in such terms. Sceptics like the late historian Inga Clendinnen argue that the use of this concept might prevent us from identifying the social and historical contributing factors that often lie behind extreme wrongdoing.

Some critics also make the further criticism that using the concept of evil leads us to write people off, to mistreat outsiders, or to ‘shutdown enquiry into the causes of extreme wrongdoing’. Evil people simply become beyond the sphere of our understanding and concern.

Russell’s response to such criticism is instructive. He concedes that these criticisms of the potential damage do have some merit but nonetheless do not warrant abandoning evil as a relevant normative category. He distinguishes between evil actions and evil people and then notes that, although evil actions are comparatively common, evil persons are rare. Hence, fears of widespread exclusion are unfounded since the number of genuinely evil people is small. Furthermore, Russell argues that there will be people who are irredeemable and it is naïve to think otherwise. Perhaps then we do need a concept of evil?

My own sympathies lie with what we might call Waitsian scepticism. Particularly when it comes to talk of evil persons (as opposed to evil actions), it is difficult to see what precisely is gained by categorising some people as evil. One cannot help but think that perhaps talk of evil is just a rhetorical trope that provides us with the vocabulary to express our utter dismay at the badness of some actions.

However, one need not accept that evil is a genuine explanatory category to find the explorations of moral psychology herein illuminating. Being Evil contains extended discussions of many gruesome events – murders, torture, acts of terror – that have shocked the public in recent years. Russell provides thoughtful and sensitive explanations of how best to understand the harm caused in his chosen cases, all of which assists in contextualising the more abstract philosophical theorising. It is a book that inspires genuine reflection on what it is that makes extremely violent and cruel acts so repugnant and how we might best respond to them.