Near the end of his life, Adam Smith returned to The Theory of Moral Sentiments, his first book and in his estimation, if not history’s, his best. He had recently finished extensive revisions to The Wealth of Nations, and, as with that work, he felt the need to make a few final additions before “the great change” came to pass. In addition to reflections on suicide and, implicitly, the incarnadine extravagances of the Jacobin radicals, Smith’s last words included these:

This disposition to admire, and almost to worship, the rich and the powerful, and to despise, or, at least, to neglect persons of poor and mean condition, though necessary both to establish and to maintain the distinction of ranks and the order of society, is, at the same time, the great and most universal cause of the corruption of our moral sentiments.

So spake the architect of modern economic thought. The statement was occasioned by the observation that wealth and power are commonly accorded “the respect and admiration which are due only to wisdom and virtue.” This is the eternal lament of philosophy—or, more precisely, the eternal lament of the philosopher—but it had special resonance for a man who spent his life describing an ethics of propriety and an engine of wealth. The “distinction of ranks and the order of society” were the cultural and political embodiment of propriety, and insofar as Smith had provided a blueprint for the aggregation of wealth, he knew that he had magnified its potential not to warp the norms of propriety, but to become their center of gravity.

As a moral and practical matter, Smith’s fear is plainly expressed by the Harvard philosopher Michael Sandel: “The more money can buy, the more affluence (or the lack of it) matters.” The statement is both the premise and the primary challenge of Sandel’s new book, What Money Can’t Buy: The Moral Limits of Markets. Money, Sandel tells us in his introduction, can buy you an upgraded prison cell in Santa Ana, the right to shoot a black rhino in South Africa, and a surrogate mother in Bangalore.

But the Parade of Horribles has only begun, and, as Grand Marshall, Sandel is prepared for the times (and there are not a few of them) when we shake our heads and ask Is nothing sacred? His answer is hardly comforting: Not in a world where everything has a price.

Take, perhaps, his most troubling example: body billboards. Sandel briefly relates the story of Kari Smith. In 2005, the 30-year old Utah woman put her forehead up for auction on Ebay. She hoped to raise money for her son’s education, but news accounts make clear that she was also burdened by the kinds of domestic tragedies—a broken marriage, the death of several family members—that can trigger a search for meaning. “I really want to do this,” she told the Deseret Morning News. “To everyone else, it seems like a stupid thing to do. To me, $10,000 is like $1 million. I only live once, and I’m doing it for my son.”

$10,000 is what GoldenPalace.com paid for Kari Smith’s forehead. When bidding reached $999.99, the online gambling site exercised the Buy It Now option, a strike price that ended the auction two days early. Including that option was obviously not Ms. Smith’s worst decision, but it was certainly ill-advised. Months earlier, the site had paid over $15,000 to another woman to legally change her name to goldenpalace.com and, less than a year later, it would pay $75,000 for William Shatner’s kidney stone.

Boldly going where no online casino has gone before has been a successful free-media strategy for GoldenPalace, which has purchased the rights to at least one other forehead in addition to over 100 arms, legs and backs. “We couldn’t come up with an advertising campaign like this and try to make people get these tattoos,” a representative for the company gamely admitted. “But if they’re putting it out there, it’s good for them and it’s good for us.”

The logic of that sentence is cozy and twisted. For Sandel, it is also too familiar. “When we decide that certain goods may be bought and sold,” he says, “we decide, at least implicitly, that it is appropriate to treat them as commodities, as instruments of profit and use.” This is a sinister variation on an age-old problem. Money has always been the hoary handmaid of corruption, conferring power on those who have over those who would. As Timon says of gold in Shakespeare’s sordid play:

This yellow slave / Will knit and break religions, bless the accursed; / Make the hoar leprosy adored, place thieves / And give them title, knee and approbation / With senators on the bench

Thus the Athenian calls money the “common whore of mankind,” a telling description, as it retains the meretricious quality of the relationships it facilitates. The thief may enjoy the genuflections of a purchased position, but they are not freely given, and no one thinks he’s deserving.

In his 1983 book, Spheres of Justice, Michael Walzer warned against the tendency of a single good becoming a “social version of the gold standard,” whose power dominates the distribution of goods in every sphere of life. “Money is inappropriate in the sphere of ecclesiastical office,” he says by way of illustration, “it is an intrusion from another sphere. And piety should make for no advantage in the marketplace.” Walzer instead champions “a diversity of distributive criteria that mirrors the diversity of social goods,” a state of affairs he calls “complex equality.” A million dollars might get you a Maserati, but it shouldn’t entitle you to solo show at MoMA or, for that matter, a Senate seat.

Walzer calls “tyranny” the instinct that contends otherwise, a term he defines after Pascal as “the wish to obtain by one means what can only be had by another.” Sandel seems broadly sympathetic to this notion—what we might call Justice as Propriety—but his book dwells on the fact that money not only allows us to breach the norms of proper behavior, it changes them as well. As an example, he cites the famous Israeli study in which the administrators of a series of childcare centers tried to deal with the problem of late-arriving parents by assessing them a fine for tardiness. But instead of underlining the offense, the fine seemed to void it. Parents now regarded “a late pickup as a service for which they were wiling to pay.” The fine became a fee, and late arrivals increased.

Such a development would not have surprised the fat friars of Boccaccio’s world. When a fine for sin became a fee for absolution, their coffers grew full. But so too did the Devil’s. Simony did not change the underlying impiety of certain actions, it simply turned them to an abbot’s best advantage. When a practice comes under the spell of market forces, on the other hand, its moral significance does tend to change. “[M]arkets are not mere mechanisms,” Sandel says, “They embody certain norms. They presuppose—and promote—certain ways of valuing the goods being exchanged.” In other words, don’t forget: When it’s okay to buy something, it’s okay to buy something.

This seems like an uncontroversial observation, even banal, but for Sandel, it is a blindspot for those economists who would promiscuously introduce market forces into all types of human activity. They, not Walzer or Smith or any other philosopher, are the interlocutors of his book. Over the last forty years, he says, these economists “have set themselves a more ambitious project” than one that limits itself to “the production and consumption of material goods.” He cites the Nobel Prize winning economist Gary Becker’s book The Economic Approach to Human Behavior as providing an intellectual call to arms for the belief that “the economic approach is a comprehensive one that is applicable to all human behavior.” For Sandel, such an approach translates into a kind of coarse-grained utilitarianism that understands the mechanics of human decision-making in terms of a commercial cost-benefit analysis. The example he provides from Becker illustrates the frontiers of this thinking:

According to the economic approach, a person decides to marry when the utility expected from marriage exceeds that expected from remaining single or from additional search for a more suitable mate. Similarly, a married person terminates his (or her) marriage when the utility anticipated from becoming single or marrying someone else exceeds the loss in utility from separations, including losses due to physical separation from one’s children, division of joint assets, legal fees, and so forth. Since many persons are looking for mates, a market in marriages can be said to exist.

Sandel’s objection is not that you cannot conceive the practice of getting married as a market practice, but that if enough people do, that way of thinking exerts a kind of gravitational pull that inevitably shapes the laws, customs, and opinions surrounding the institution. What we today understand as “marriage” inevitably changes, and not for the better.

Again, for Sandel, such an observation verges on commonsense even if many economists seem stubbornly unwilling to acknowledge the subversive implications of their thinking. For them, the introduction of markets—whether for foreheads, late pick-ups, or any one of a growing group of unlikely “goods”—is morally neutral. Markets render human behavior more efficient, as opposed to shading or fundamentally reshaping it. Economics “simply doesn’t traffic in morality,” Sandel quotes the economist Stephen Levitt as saying in his best-selling book Freakonomics. “Morality represents the way we would like the world to work, and economics represents how it actually does work.”

To Sandel’s ears, this is dangerous nonsense, and like a prosecutor pursuing his case, his book works by presenting considerable evidence to the contrary. The case he makes is convincing at the same time that it raises more questions than it answers. Describing a few of the harder ones, Sandel says

once we see that markets and commerce change the character of the goods they touch, we have to ask where markets belong—and where they don’t. And we can’t answer this question without deliberating about the meaning and purpose of goods, and the values that should govern them.

One might criticize Sandel for sidestepping such questions, but this would be to fundamentally misunderstand his book, which is a work of provocation rather than prescription. The approach reflects Sandel’s teaching style, made famous by his Justice class, for many years the single largest course at Harvard and in 2009 becoming a successful PBS series. Philosophy, he tells his students, is “a distancing, even debilitating activity,” one that works by “taking what we know from familiar, unquestioned settings and making it strange.”

There are few facts of the modern world more familiar than the prevalence of markets and the preeminence of wealth. These are recent developments with increasingly global purchase. For Sandel, their impact must be measured in dollars and sense.