Why PPE?

Philosophy, Politics, and Economics (PPE) began as an interdisciplinary degree program at Oxford in 1920, and ninety years later it has spread to well over a hundred universities around the world as either a major or minor area of study. The original idea was, in part, to provide future civil servants in the United Kingdom with an opportunity to become generalists by exploring public policy through the different lenses of complementary disciplines.

Over the past few decades, as PPE made its way to the United States, the curriculum and tools of analysis have changed considerably. The more recent version of PPE was shaped by people like Geoffrey Brennan, an economist-turned-philosopher from the Australian National University and the Founding Director of the joint Duke/UNC PPE program. As Brennan conceives it, politics is a domain of study, but economics and philosophy provide the tools that help us explain, predict, and evaluate behavior under alternative political institutions.

This description of PPE is, of course, incomplete. Another focus of PPE students is on economics rather than politics—especially on studying how markets work and how the division of labor that markets promote affects human welfare and intellectual progress. As early “political economists” such as Hume, Smith, Marx, and Mill recognized, market exchange typically operates in the context of a political system that determines what can be owned and traded, which contracts will be enforced, and which activities will be permitted or prohibited. All these facts affect the welfare of market participants and the distribution of goods that market exchange produces.

Those of us who teach in PPE programs, and who do scholarship from a PPE perspective, tend to take seriously the importance of social scientific models and empirical results, and to incorporate them, when appropriate, into our normative analyses.

For example, while we may have moral concerns about exchanging sex or drugs or human organs for money, arguments for making these activities illegal are a much more delicate matter. We might start with the kinds of questions with which moral philosophers are familiar: do these exchanges harm others in morally significant ways? Do the harms have compensating benefits? Regardless of any harms (or social costs) associated with them, do individuals have natural rights to the things they obtain through voluntary exchange, or is the system of exchange just a social convention for maximizing human welfare?

Answering questions like these is important but doesn’t settle the issue: even if we agree that there’s something wrong with, for example, trading money for sex, making prostitution illegal doesn’t make it go away. Moreover, there are costs to enforcing laws, and these include non-monetary costs such as potential invasions of privacy and police corruption, as well as the cost of financing courts and prisons, all of which will be differentially borne by people who are rich or poor, male or female, and urban or rural.

Economic tools are especially important for PPE students who want to understand how illegal (“black”) markets work. For example, in microeconomics we often speak of the elasticity of demand, which measures how much demand changes as the marginal cost of the item demanded goes up or down. One of the interesting connections between markets for sex and drugs and markets for body parts is that the first two pertain to intense sources of pleasure, and the third pertains to a necessary condition for human life, so many people are willing to pay a lot of money and take on tremendous risk to get these things.

When demand for certain goods is relatively inelastic, PPE students have the tools to think about the consequences of making it illegal to buy and sell them. In other words, when confronted with morally problematic actions and imperfect institutions, good PPE students are adept at asking the question, compared to what?

Thinking in comparative terms is crucial, but of course, it doesn’t solve the problem, and this is where philosophy comes in. When economists ask whether a consumer good should be taxed or banned or permissibly traded, they tend to rely exclusively on an efficiency standard (roughly, efficiency tracks the utilitarian view that social welfare is maximized when more aggregate preferences are satisfied). But philosophers have a lot to say about which preferences count and whether things other than preferences might matter.

While there are disagreements over the nature and scope of PPE among those who teach it, Elizabeth Anderson thinks (and I agree) that collective action problems are a core part of the agenda. Collective action problems occur when there are benefits to coordinating our activities but incentives to free ride on the efforts of others, and when there is (as in many cases) imperfect information about the motivations and actions of other people with whom we need to coordinate to achieve a common goal.

A good PPE student will encounter a collective action problem like anthropogenic climate change or antibiotic resistance (both of which are global and intergenerational) and be able to use the tools of game theory to figure out whether it is best modeled as a prisoner’s dilemma or an assurance game, or something else altogether. She will also be able to think through whether a particular set of actions is an equilibrium (or stable point) in the game, and whether we might be able to use social norms or legal sanctions to move to a superior equilibrium at a sufficiently low cost. In other words, PPE helps us model problems that arise when we interact with each other and then evaluate the tradeoffs among the politically feasible and morally desirable set of solutions. Sometimes the solution is simply to allow people to communicate and share information; other times norms or laws are needed to solve the problem.

Finally, PPE students study how economic tools like game theory and utility theory can illuminate problems in political philosophy. Economists emphasize that in markets, people get what they pay for, but in politics, citizens get what other people vote for (when I hand over the dollar bill, I get the candy bar, but when I vote for Barry Goldwater, my vote is very unlikely to cause him to win). This simple observation has significant consequences for how people gather and sift through information in the market and in the political realm. If voters tend to be “rationally ignorant” about politics because they have very little chance of affecting the outcome of an election with their votes, this raises normative questions about the proper scope of democracy, the appropriate role of constitutions and courts, and the optimal rules for financing campaigns and crafting policy.

PPE is thriving in the U.S. and U.K. in part because students are looking for conceptual tools to help them understand and evaluate the world around them. But many of these students want to do this while asking questions they typically don’t get to ask (or don’t get complete answers to) if they take economics, politics, or philosophy classes in isolation.

For these reasons, PPE is easy to sell to students, and to administrators who are seeking more collaboration between disciplines or who want philosophy departments to show that they can impact a wider discussion. With an upfront investment in building institutional infrastructure and bringing administrators and faculty from other disciplines on board, PPE can help increase the number of philosophy majors. It can also become its own major.

In my experience, the biggest challenge to running a successful PPE program is staffing it with people with the competence and commitment to doing rigorous interdisciplinary work. A successful PPE program will exploit the division of labor and have economists teach game theory, moral philosophers teach ethics, etc. But it will also need a few generalists who have both the ability and the passion to teach gateway PPE courses (which cover basic principles) and capstone PPE courses (which apply those principles to specific issues). Finally, it helps to have an energetic director who—like Elizabeth Anderson, Cristina Bicchieri, Jerry Gaus, Geoff Sayre-McCord, or Michael Munger—understands and respects the relevant disciplines and is good at bringing people together.

Further Resources:

• Anomaly, Brennan, Munger, Sayre-McCord, Philosophy, Politics, & Economics.  Oxford University Press, 2016
• Jerry Gaus and John Thrasher, Philosophy, Politics, and Economics: An Introduction. Princeton University Press, 2021.
• Hausman, Daniel and MacPherson, Michael. Economic Analysis, Moral Philosophy, and Public Policy. Cambridge University Press, 2006.
• Resources for teaching PPE

If you would like to submit a contribution, we’d love to hear from you.  Please contact us via the submission form here. 

Jonny Anomaly

Jonathan Anomaly is Associate Director of PPE at the University of Pennsylvania.  He has helped build PPE programs at Virginia, Duke, UNC, and Arizona.  Anomaly’s publications can be found here.