Imagine that you and I buy the same product from the same website at the same time, yet you pay more than I do. The difference is that the seller knows something about each of us. Perhaps your browsing history, shopping behavior, location, or some other factor suggests that you are willing to pay more than I am. Is this fair? More importantly, is it illegal?

The Federal Trade Commission (FTC) is thinking about this. This issue is whether there is something about personalized pricing—pricing that treats customers as individuals rather than groups—that increases the chances of unfair or deceptive business practices, as the FTC defines them. It has proposed an enforcement policy that would scrutinize businesses that use personalized pricing.

The concern is understandable, but misplaced. Digitization gives businesses far more information about customers than they previously possessed. And machine learning makes it increasingly possible to use that information to estimate what an individual might be willing to pay. But knowing that prices can be personalized tells us little about whether consumers are harmed.

The standard textbook example of personalized pricing considers a monopolist that knows precisely what each customer is willing to pay, and charges accordingly. The monopolist makes higher profits and higher-end consumers lose the surplus they would have received if prices were uniform. This might sound ominous, but it leaves out much of what happens in actual markets.

Start with competition. A business that knows you are willing to pay $100 for something might like to charge you $100. But another firm notices and, if feasible, might offer you $90, stealing your business. If firms have similar information about you, personalization can intensify competition for your business.

This isn’t simply conjecture. Prominent research has shown that personalized pricing can benefit consumers when market coverage is high. It also finds something especially relevant for policymakers: Consumers can sometimes be worse off when only some firms are able to personalize prices than when either all firms or no firms can do so. Other research reaches related conclusions, finding that consumer information can intensify competition as businesses make targeted offers to defend existing customers and attract customers from rivals.

There is no general rule that personalized pricing harms consumers or is problematic in any other way. It might benefit firms, but it can also increase competition, bring additional consumers into the market, and improve the matching of products with customers.

There is another issue that deserves more attention. Many of the analyses assume that the products in question already exist. But we know that when incumbents profit, rivals innovate. The same information that lets a business personalize prices can help it personalize products. This is already happening in e-commerce, entertainment, travel, and education. As the costs of customization decline, both prices and products become increasingly personalized. Regulations that make personalization less profitable will lower incentives to innovate.

The FTC’s proposal recognizes that personalized pricing is not unlawful in itself. But it states that when consumers reasonably expect prices not to vary with personal data, businesses using personalized pricing should disclose the personalization, its basis, and the types of data used. Failure to do so, the FTC says, is likely to constitute an unfair or deceptive practice. That puts a lot of weight on “reasonable expectations” and the presumed value of disclosing trade secrets.

People certainly care about fairness. But perceptions of fairness differ among people and change with experience. Americans do not even agree about whether our economic system itself is fair. Trying to turn such perceptions into a policy encourages arbitrary enforcement.

Besides, consumers already have ways of responding to situations they consider unfair. Richard Thaler’s work on transaction utility shows that people care about more than just prices. They care about the nature of the deal and respond accordingly. Businesses that violate customers’ senses of fairness lose business.

None of this means businesses should be free to deceive customers. The FTC should pursue violators based on current legal standards, applying them equally regardless of whether prices are uniform, personalized, or something in between. Research gives us little reason to believe that principles should change as knowledge increases.