In two earlier Freeman essays, I explored the idea that “ought implies can” and the role of profits in providing knowledge about how best to serve others.

Both insights rely on the foundational idea that intentions and results are not the same thing. Thinking we ought to do something does not mean it will have the results that motivate the “ought.” With respect to profits we have to recognize that because someone does something to benefit himself, it does not mean the action doesn’t benefit others too. In both cases the core concept that is often overlooked is unintended consequences. Recognizing that intentions do not equal results and that we must consider the possibility of unintended consequences is what separates good social analysis from bad.

The issue of unintended consequences is interrelated with a more general aspect of human social existence: the pervasiveness of uncertainty. The future is not available to us in the present. We cannot know the course of nature, but neither can we know the course of human choices. We are always acting based on our best guesses about what others will do and how our actions will coordinate with theirs, which we can never know with certainty. This structural uncertainty of the human condition means that we can never know all the consequences of our choices, which implies that some of those consequences will be other than what we intend. Anyone who believes the consequences of his actions will be exactly as intended is blind to the fact that his choices must interact with those of others, creating outcomes that none of the choosers designed.

Unintended consequences come in two flavors: positive and negative. The concept of negative unintended consequences is acknowledged in some social analyses and in morality, but is certainly underdeveloped in the understanding of economic policy. Positive unintended consequences are rarely recognized in “serious” conversations about public policy, even though they are at the core of modern economics.

Consider the two-by-two matrix below.

We have moral language for three of the four possible combinations of intent and outcome. Vice and virtue are easy enough, as they are our common terms for discussing the morality or desirability of our actions when the outcomes match our intentions. But what about when they don’t? We have the category of “negligence” when we cause negative outcomes we did not intend, such as failing to set the brake on a car that rolls down a hill and damages property. But we do not have a word for the unintentional doing of good! That missing box is filled in by economics and good social science as they explain how, under the right institutional framework, the pursuit of self-interest leads to unintended benefits for society as a whole.

Naming the Unintentional Good

From Adam Smith in the eighteenth century to Carl Menger in the nineteenth to Ludwig von Mises and F. A. Hayek in the twentieth, the central mission of economics has been to understand how we can produce beneficial outcomes that were not intended. Smith captured this idea with the “invisible hand” that leads the butcher, baker, and brewer to provide us with our dinner not out of altruism but “self-love.” Smith understood how exchange guided by prices and profits would harmonize (to use a term associated with Frédéric Bastiat in the nineteenth century) the self-interest of producers with the self-interest of consumers. Even if we care not at all about the people we trade with, we will nonetheless be led to satisfy their wants in our attempt to satisfy our own. Looking only at the seller’s profits without tracing out the entire chain of beneficial though unintended consequences that his self-interest produces is to take an “unscientific” approach to understanding society.

Menger put the concept of unintended consequences (and the closely related idea of “spontaneous” or “unintended” order) at the center of his conception of the social sciences. In what is often termed “the Mengerian question,” he asked: “How can it be that institutions which serve the common welfare and are extremely significant for its development come into being without a common will directed toward establishing them?” Menger recognized that many social institutions are not the product of human design, but instead emerge as people seek their own self-interest. Menger’s own classic work on the evolution of money explains how it arose this way from barter.

Mises and Hayek deepened this argument another layer as both recognized, with somewhat different emphases, the role that knowledge plays in understanding the centrality of unintended consequences in social thought. Mises provided what we might call the “microfoundations” of Smith’s invisible hand by carefully explaining how we go from people’s subjective perceptions to market-level outcomes via prices, which facilitate our calculations about the effectiveness of the use of resources. Mises also explored how profit and loss provide further signals that serve as “aids to the mind” in guiding our behavior. Entrepreneurs are led to use resources wisely, profiting for themselves but also improving the well-being of others, thanks to the signals of the marketplace.

Hayek’s work on economics, knowledge, and the problems of socialism allowed us to see the opposite side of Mises’s analysis by exploring how socialist planners would be unable to replicate the workings of entrepreneurs. Hayek argued that without market signals government planners would be unable to marshal the dispersed knowledge available to entrepreneurs through prices and other market institutions. Because of their ignorance, planners would not only be unable to generate beneficial unintended consequences in their own pursuit of self-interest, they would in fact cause harmful ones by being unable to see how their mistakes would lead to further mistakes—not to mention accumulating State power. Both Mises and Hayek saw that regardless of the socialist planners’ good intentions, their inability to make use of the knowledge of the marketplace would lead to consequences very different from those intended—in fact, as history has clearly demonstrated, consequences devastating for millions.

Institutions Against Uncertainty

The Smith-Menger-Mises-Hayek line of thought can be tied back to our earlier discussion of uncertainty. This tradition argues that we use evolved social institutions, including the market, to get more accurate expectations of the behavior of others and push back against the uncertainty that threatens to derail our plans. At the simplest level we see this with prices: The prices of particular goods or services are “aids to the mind” regarding the preferences, knowledge, and expectations of others, enabling us to better anticipate the consequences of our choices and to thereby make better ones. Institutions that emerge as a result of unhampered social evolutionary processes all perform this uncertainty-reducing function.

Consider the institution of ownership. When someone says that he “owns” a particular good, we know that gives him a certain set of rights to it and imposes certain obligations, largely negative ones, on us. Knowing that the good is owned means we can form particular expectations about what the other person might and might not do with that object, and he in turn can have reliable expectations about what we will and will not do.

An irony of social institutions is that by limiting our choices they make us better able to execute our plans and anticipate their likely consequences. However, to perform that coordinative function in complex matters and help us overcome uncertainty, institutions need to emerge from people’s voluntary interactions, usually over a period long enough for them to embody the best ways of doing things. This is why markets are so good at generating positive unintended consequences and why institutions imposed by force from the top down tend to generate negative ones. Just as we are much more productive as a society when entrepreneurs and consumers have access to competitively determined prices, so in general does human action produce beneficial unintended consequences when social institutions generally are the result of unhampered evolutionary processes.

Even in less dramatic ways modern economics remains focused on unintended consequences, particularly in how economists like to make highly counterintuitive arguments. For example, a number of years ago there was a call for government to require very young children to sit in car seats rather than on their parents’ laps when flying on airplanes. This arose out of concern that in some circumstances lap children could be hurt or could hurt others. Critics, particularly economists, quickly responded that such a law would actually kill more children than it saved.

To see why, one has to explore the unintended consequences. Under the law parents would have had to buy tickets for children who formerly flew free in their laps. Faced with the additional charge, some families on the margin would switch from flying to driving. But the odds of being injured or killed in an automobile are much greater per mile than in a plane. Thankfully, that unintended consequence was anticipated before it was too late, saving many children in the process.

The idea of unintended consequences also helps us understand one process by which government has grown over the last century or two. Because even well-intentioned interventions produce consequences that political actors could not foresee and did not intend, every time government acts, it creates a new set of problems that in turn leads to calls for more government solutions.

A final observation: The neglect of unintended consequences and the focus on motives lead us to celebrate the lives and mourn the deaths of politicians, although they may have caused undesirable unintended consequences, while inventors and businesspeople who benefit humanity while pursuing their own ends go unnoticed. As my matrix on the previous page suggests, we simply don’t have a moral category for people who unintentionally benefit others in pursuit of their self-interest. And we also highly overvalue intentions as a measure of moral worth, leading to praise for those whose “hearts were in the right place” even as they have caused incalculable damage to prosperity and freedom.

A better understanding of the idea of unintended consequences will not only give us the tools we need to more accurately analyze social issues, it will also provide us with a different way of making moral judgments. After all, it is results that count, and we all know where the road paved with good intentions leads to.