WASHINGTON – There have been various attempts over the decades to bury moral philosophy – to dismiss convictions about right and wrong as cultural prejudices, or secretions of the brain, or matters so personal they shouldn’t even affect our private lives.

But moral questions always return, as puzzles and as tragedies. Would we push a hefty man onto a railroad track to save the lives of five others? Should Petty Officer 1st Class Marcus Luttrell, in June of 2005, have executed a group of Afghan goatherds who, having stumbled on his position, might inform the enemy about his unit? (Luttrell let them go, the Taliban attacked, and three of his comrades died.)

These examples and others – price gouging following Hurricane Katrina, affirmative action, gay marriage – are all grist for the teaching of Michael Sandel, perhaps the most prominent college professor in America. His popular class at Harvard – Moral Reasoning 22: Justice – attracts about a sixth of all undergraduates. For those lacking $49,000 a year in tuition and board, he has written “Justice: What’s the Right Thing to Do?” which has been further translated into a PBS series and a Web site, justiceharvard.org.

Sandel practices the best kind of academic populism, managing to simplify John Stuart Mill and John Rawls without being simplistic. His discussion of Immanuel Kant’s case against casual sex was almost enough to make me dig out my college copy of “Critique of Pure Reason.” Almost.

But Sandel is best at what he calls bringing “moral clarity to the alternatives we confront as democratic citizens.” In this cause, he outlines three attempts to define the meaning of justice, each with large public consequences.

Definition one is the maximization of social welfare – the greatest happiness for the greatest number. But utilitarianism, in Sandel’s view, has glaring weaknesses. It allows no principled defense of individual rights. What if the sum of social happiness is increased by throwing a minority to the lions? And utilitarianism ultimately can make no distinction between fulfilling higher forms of happiness and degraded ones. Why should we prefer the pleasures of art museums to the pleasures of dog fighting?

A second definition of justice consists of respecting individual freedom. This approach can take the form of market-oriented libertarianism – the belief that justice is identical to the free choices of consenting adults. Or it can have a more egalitarian expression, in which society is organized for the benefit of its least advantaged members. But both of these views assume that government’s only job is to set fair rules and procedures; it is entirely up to free individuals to choose the best way to live.

Many Americans would find this view not only unobjectionable but also unassailable. Sandel assails it. “I do not think,” he says, “that freedom of choice – even freedom of choice under fair conditions – is an adequate basis for a just society.”

This equation of justice with freedom, he says, is unrealistic about the way human beings actually live. Our views of right and wrong, duty and betrayal, are not merely the result of individual free choice. All of us are born into institutions – a family that involves our unconditional love, a community that elicits feelings of solidarity, a country that may demand a costly loyalty. Sandel argues that a liberal individualism cannot explain these deep attachments. We are “bound by some moral ties we haven’t chosen.”

Sandel, in the good company of Aristotle, contends that knowing “the right thing to do” in any of these institutions requires a determination of its purpose. And the purpose of government is not only to defend individual rights, but also to honor and reward civic virtues – patriotism, self-sacrifice and concern for our neighbor. This third definition of justice, by nature, is a moral enterprise.

Because Sandel is a progressive, he calls this approach “communitarian.” The stars of his political firmament are Robert Kennedy, for his call to vigorous citizenship, and Barack Obama, for his recognition that social justice is often based on moral ideals. But Sandel’s belief in family and community, his respect for religious motives and his defense of patriotism might also be called conservative, at least in an older sense of the term.

Sandel sets out to confront the most difficult moral issues in politics. He ends up clarifying a basic political divide – not between left and right, but between those who recognize nothing greater than individual rights and choices, and those who affirm a “politics of the common good,” rooted in moral beliefs that can’t be ignored.

© 2009, Washington Post Writers Group