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For the lasthalf-century, the world’s leading universities have taught microeconomicsthrough the lens of the Arrow-Debreu model of general competitive equilibrium.The model, formalizing a central insight of Adam Smith’s The Wealth of Nations,embodies the beauty, simplicity, and lack of realism of the two fundamentaltheorems of competitive equilibrium, in contrast to the messiness andcomplexity of modifications made by economists in an effort to capture betterthe way the world actually functions. In other words, while researchers attemptto grasp complex, real-world situations, students are pondering unrealistichypotheticals.
This educational approach stems largely from thesensible idea that a framework for thinking about economic problems is moreuseful to students than a ragbag of models. But it has become burdened withanother, more pernicious notion: as departures from the Arrow-Debreu modelbecome more realistic, and thus more complex, they become less suitable for theclassroom. In other words, “real” microeconomic thinking should be left to theexperts.
To be sure, basic models – for example, theoriesof monopoly and simple oligopoly, the theory of public goods, or simpleasymmetric-information theory – have some educational value. But fewresearchers actually work with them. The bread-and-butter theories formicroeconomics research – incomplete contracts, two-sided markets, riskanalysis, inter-temporal choice, market signaling, financial-marketmicrostructure, optimal taxation, and mechanism design – are far morecomplicated, and require exceptional finesse to avoid inelegance. Given this,they are largely excluded from textbooks.
In fact, microeconomics textbooks have remainedpractically unchanged for at least two decades. As a result, undergraduatestudents struggle to understand even the abstracts of papers on the complexrepresentations of microeconomic reality that fill research journals. And, inmany areas – such as antitrust analysis, auction design, taxation,environmental policy, and industrial and financial regulation – policyapplications have come to be considered the domain of specialists.
This does not have to be the case. While it istrue that realistic microeconomic models are more complex than their idealizedtextbook counterparts, grasping them does not necessarily require years ofresearch experience.
A case in point is the economics of two-sidedmarkets, which involve competition between platforms whose principal “product”consists in connecting two categories of users, who then offer each othernetwork benefits. When markets are two-sided, many of the standard assumptionsof antitrust analysis no longer hold: market entry can be bad for consumers,exclusive contracts can increase the number of firms in a market, and pricingbelow cost may not be predatory.
A survey byDavid Evans and Richard Schmalensee describes numerous situations in whichapplying old assumptions could lead to mistakes by, say, an anti-trustregulator with only an undergraduate degree. The unmistakable message is,“Don’t try this at home.”
But every behavioral divergence betweentwo-sided and traditional markets can be understood using simple tools ofelementary microeconomics, such as the distinction between substitute andcomplementary products. When producers of substitutes collude, they usuallyraise prices; producers of complements, by contrast, collaborate to lower them.
So, if two platforms that appear to beperforming similar services are complementary – for example, because oneplatform connects consumers with a set of users that helps them to valueanother set of users more highly – market entry can be bad for consumers. Infact, two platforms can even be complementary for one set of users andsubstitutes for another. The different stages of a televised soccer (football)tournament, for example, are complementary for viewers and substitutes foradvertisers.
Moreover, exclusive dealing can increasecompetition by allowing two platforms to occupy distinct market niches, withthe alternative being that one drives out the other. In short, with a solidunderstanding of the difference between complements and substitutes, one can doalmost everything the fancy models do – without hiring a single expensiveexpert.
Undergraduate-level microeconomics shouldempower students, not alienate them. While the Arrow-Debreu model has its value– namely, it explains why an unplanned economy can produce order – it isdiscouraging for students to find that what they are deemed capable of comprehendingoffers little insight into real-life situations.
Restructuring the microeconomics syllabus wouldsend a far more inspiring – and accurate – message: even complex ideasdeveloped by experts can be understood and applied by educated laypeople.
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