"War killed an average of over a hundred people an hour through the 20th century,” writes Jonathan Glover. One can only wonder what the 21st century will bring. Glover, director of the Centre of Medical Law and Ethics at King’s College in London, undertakes the momentous task of offering a moral history of the past century. According to Glover, it is the history of the failure of our humanity and the concurrent rise of barbarism. He charts the constant threat of barbarism and struggles to build up ethical defenses against it.

In writing any history of the recent past, factual error is a danger, as is distortion of perspective, oversimplification or faulty inference. The difficulties mount if one purports to write a moral history. How is the author to avoid moralizing, biased judgments or, perhaps worse, a simple reading of history as moral progress or moral decline?

Though Glover is aware of all of these dangers, he persists in his task. He believes that the moral reflection of those who have been spared the most horrendous events of the past century can be true only if it grapples with what others have suffered and done. Only in so engaging the past can we expand our moral imaginations and escape the confines of our limited social and moral experience. In the process, Glover suggests, we may also discover something about the structure of moral experience that emboldens us to struggle against forces of injustice.

Glover does not spare us the details of a century of untold blood and savagery, yet his main focus is on a reality that he believes lies beneath the horror—the fading of the moral law. “The idea of a moral law external to us may never have had secure foundations, but, partly because of the decline of religion in the Western world, awareness of this is now widespread. Those of us who do not believe in a religious moral law should still be troubled by its fading.”

Throughout most of Western history people have believed in some kind of moral order within which they made sense of their lives. Morality was justified religiously through the idea that human beings are created in the image of God, or rationally through such ideas as the notion that all humans have the capacity to know the good. These justifications are now lost to us, Glover contends.

Whether the phenomenon is called the death of God, the modern disenchantment of the world, the loss of a background of value or the failure of an ethical attitude toward nature, Western peoples’ sense of a moral order to which they can, may or must conform has diminished. Indeed, many consider the very idea tyrannical—a denial of the individual’s right to free choice. The escape from a morally deep world was undertaken in part to celebrate freedom and to energize human creativity. Since classical moral realism—the idea that moral values are rooted in objective reality and so have factlike status—has vanished, we need other sources to direct human life and combat barbarism. This is the moral challenge that launches Glover’s book.

Glover contends that moral reflection must move in an empirical and psychological, rather than a rational and religious, direction. It must seek to reconstruct ethics around people’s revulsion toward violence and their consequent attempt to restrain violence. One must look close and hard, therefore, at what forms and deforms moral sensibilities.

Glover argues that three sensibilities restrain violence: sympathy, recognition of human dignity, and a sense of moral identity. People sense a moral bond with others and restrain their actions because of their sympathy with others’ suffering, their acknowledgment that others are due respect, and their belief that acts of violence toward others would destroy their own sense of self and community. Sympathy, dignity and moral identity are features of most of our lives most of the time, which is why the world is not normally torn apart by festivals of cruelty. Ethics can be reconstructed on the basis of these features of ordinary life, Glover believes, without recourse to disputed rational axioms or religious beliefs.

Glover is not alone in recognizing the loss of moral depth to life. Many have attempted to respond to the new situation. Indeed, the work of reconstruction has been the central business of contemporary moral theorists. Some thinkers, especially conservative theologians and cultural critics, appeal to their specific faith or moral traditions. Moral reason and moral identity, they insist, are constituted exclusively by the traditions that shape us. The problem for any moral community is to form people with the virtues necessary to live rightly with others.

Other moral thinkers narrow morality to the simple demand for nonmaleficence and socially defined norms of justice. In this case, morality is reconstituted not in terms of virtues and a vision of the good life, but in terms of the minimal demands of justice necessary for some measure of social tranquillity. Still others try to work out a phenomenology of moral experience. They try to show that, at least with respect to human beings, life is permeated with a worth that evokes respect, dedication to enhance life and constraints that limit the wanton use of power. Glover moves between delineating a psychology of sympathy, dignity and moral identity and presenting detailed historical studies of the most heinous events of the past century. He shows what light a specific moral psychology throws on human events and also how those events sharpen awareness of the fragility of our moral condition.

It is notoriously hard to make goodness compelling, whereas the human imagination is gripped by stories of evil. Glover knows this and plays upon it, yet he still seeks to discern within the horror of the past century a glimmer of human dignity. Each of his studies—of My Lai; Rwanda and tribalism; Stalin; the Nazis—explores how the normal restraints on violence (rooted in sympathy, dignity and moral identity) were overwhelmed in certain situations. He provides a fascinating if troubling examination of how belief systems, physical distance from one’s “enemy,” tribalism, humiliation and other social forces destroy normal psychological inhibitors to cruelty. The case studies offer insight into the terrible fragility of moral sensibility, the ways in which it can be manipulated and overwhelmed, and the thoroughness of that process.

One is left to wonder, and certainly Glover wonders, if any kernel of moral sensibility can remain in human beings amid such barbarous situations. The ethical question, in Christian terms, is to what extent moral awareness endures within human sinfulness. And further, what would it mean if we thought our moral sensibilities could be completely effaced? Glover’s empirical approach to ethics does not allow him to probe these kinds of questions in detail.

The moral history Glover presents is disturbing not only for what it relates but also for what it fails to relate. Even as he seeks grounds for reviving the moral imagination and provoking moral sensibilities, Glover pictures humanity in its most depraved forms. No mention is made of the past century’s great movements of liberation, or the worldwide women’s movement, or struggles for freedom and human rights. Are these not also part of the moral history of the past century?

This point is especially consequential for Glover’s argument, since many of the resistance and liberation movements of the past century were inspired and championed by people with deep religious convictions. Mahatma Gandhi, Martin Luther King Jr., Desmond Tutu, Dorothy Day, the French Protestants who resisted fascism and protected Jews, Buddhist monks in Vietnam and many, many others were led by their religious convictions to fight for human dignity and human rights. It is necessary to remember acts of goodness if one is to provide a complete picture of moral motivation. Insofar as any history is a complex act of remembering, how and what is remembered is of utmost importance.

This is related to another concern about Glover’s ethical position. Can all forms of moral realism so easily be dismissed? To be sure, classical realism is lost to us, a development due in part to increased awareness of the extent to which the human mind and cultural forms are the irreducible prisms for any apprehension of reality. We do not see goodness in the world in the same way that we perceive natural phenomena like thunderstorms or Orion’s Belt on a chilly summer’s eve. But don’t the sensibilities that Glover points to—sympathy, dignity and moral identity—tell us something about the deeper texture of reality?

Recent debates about realism in ethics and about the array of basic goods that human flourishing requires make Glover’s portrait of the moral life seem thin. The issue is not so much that sensibilities are socially constructed but how they are morally cultivated. As many religious traditions testify, the ability to perceive and attend to others is part of being human, but too often it is stunted, deformed and misdirected. One must therefore work to cultivate moral awareness, sharpen the conscience, test and reform perceptions of self and others. Profound moral traditions have the means to tutor our sensibilities and transform conscience, and they do so in part through what is remembered, in part through what is believed, and in part through symbolic, ritual and textual resources that form the moral imagination.

Moral perception when it is correct is always about something. It purports to be about things and persons within a distinctly moral mode of being. Lurking throughout Glover’s book, then, is a question about human nature. What kinds of creatures are we, morally speaking? If recent discussions about realism are on the right track in confronting the fading of the moral law—and I believe they are—then the question of the depth of morality is more complex than Glover’s empirical psychology allows. For religious thinkers this is an especially pressing point. Jews, Christians, Muslims, Buddhists and Hindus hold that morality is not only a human fabrication, even though our moral sensibilities are indeed fragile. There is still a case to be made for the insights of these traditions.

But whatever one’s criticisms of Glover’s Humanity, its aim is plainly and forthrightly humane. Given that aim, religious people face a choice. They may either put their moral convictions and energies in the service of our shared humanity on this fragile planet, or they may stress local identities and a sense of moral uniqueness, and in doing so with a clean conscience allow the horror to continue. Everyone must confront certain questions in the light of the recent past. What can we human beings learn from the violence of the past century? Can we escape the entrapments that foster and lead to violence? How do we preserve our humanity? How have our religious traditions fostered and continued to foster untold acts of barbarism?

Believers in every tradition need to articulate a historically honest, realistic and yet truly humanistic version of their convictions. That is the work ahead for those of us who have escaped the 20th century’s more horrendous forms of violence but who now find the forces of cruelty working within our own traditions.