When we decide that certain goods may be bought and sold, we decide, at least implicitly, that it is appropriate to treat them as commodities, as instruments of profit and use. But not all goods are properly valued in this way. The most obvious example is human beings. Slavery was appalling because it treated human beings as a commodity, to be bought and sold at auction. Such treatment fails to value human beings as persons, worthy of dignity and respect; it sees them as instruments of gain and objects of use.
Something similar can be said of other cherished goods and practices. We don’t allow children to be bought and sold, no matter how difficult the process of adoption can be or how willing impatient prospective parents might be. Even if the prospective buyers would treat the child responsibly, we worry that a market in children would express and promote the wrong way of valuing them. Children are properly regarded not as consumer goods but as beings worthy of love and care. Or consider the rights and obligations of citizenship. If you are called to jury duty, you can’t hire a substitute to take your place. Nor do we allow citizens to sell their votes, even though others might be eager to buy them. Why not? Because we believe that civic duties are not private property but public responsibilities. To outsource them is to demean them, to value them in the wrong way.
These examples illustrate a broader point: some of the good things in life are degraded if turned into commodities. So to decide where the market belongs, and where it should be kept at a distance, we have to decide how to value the goods in question—health, education, family life, nature, art, civic duties, and so on. These are moral and political questions, not merely economic ones. To resolve them, we have to debate, case by case, the moral meaning of these goods, and the proper way of valuing them.