IN EARLY JUNE, Barack Obama clinched the Democratic Party's nomination for president, besting Hillary Clinton in the most amazing primary battle in the contemporary era. The immediate cause of Clinton's departure from the race was probably Obama's lead in pledged delegates--which, by the end of the primary season, stood at a small-but-significant 106, out of 3,406 total pledged delegates. (1) It was simply impractical for Clinton to count on the so-called "superdelegates" to close the gap between the two.
Meanwhile, Obama's lead in the actual vote count was vanishingly small, just 150,000 votes out of 35 million cast for the two, without Michigan having fully participated. Thus, by the end of the primaries, Obama had amassed a 3.1 percent lead in pledged delegates, compared to a 0.4 percent lead in votes. This implies that Obama's voters were more efficient than Clinton's voters at producing delegates. Indeed, for every Obama delegate, there were 10,788 Obama supporters. For every Clinton delegate, there were 11,727 Clinton supporters.
This efficiency advantage probably made the difference for the junior senator from Illinois. If Clinton's voters had been as efficient at producing delegates as Obama's voters, his lead in pledged delegates would have shrunk from 106 to a paltry 14, which would have placed Clinton well within striking distance of the nomination. Thus, it behooves us to ask how it was that Obama supporters produced more delegates.
This essay will argue that Obama was favored by the delegate allocation system. In other words, Obama won not simply because he had more supporters, but also because the "rules of the game" made those supporters better at generating delegates. To see how this occurred, we will first review the voting coalitions that Obama and Clinton forged over the course of their five-month primary battle. Then, we will investigate the rules of the delegate allocation process to see how they translated each candidate's votes into delegates. First, though, comes some theoretical background--a frame of reference for understanding the importance of the rules of delegate allocation. The puzzle that we are faced with relates to a general subject matter that social scientists refer to as "social choice."
THE DEMOCRATS' DELEGATE system is designed to aggregate the individual preferences of primary and caucus voters into the choice of the party as a whole, or a social choice. Voters vote; delegates are selected according to those votes; those delegates select a nominee at the party's convention. Thus, the nomination process can be understood as a social choice mechanism that translates the preferences of Democrats nationwide into an outcome.
We should not assume that the middle step, where individual preferences are processed by the social choice mechanism, is a purely efficient one. Indeed, following Arrow's Theorem, we cannot make such an assumption. No social choice mechanism is always able to satisfy even a basic set of normative criteria. In other words, there is no "perfect" voting system. Every conceivable system has ways that the particular rules can influence the outcome, depending upon how preferences are arranged.
Thus, it is often profitable to evaluate the rules of a social choice mechanism to see how they have influenced the outcome. We shall do that for the Democratic nomination process, which is a social choice mechanism like any other. It takes the preferences of individual Democrats and translates them into a choice of all Democrats.
Our argument will be that the particular rules of the process were very important in determining the party's nominee, that there were features of the system that favored Obama over Clinton, and that slight, uncontroversial changes in the rules could have produced a different outcome. If we were to compare the nomination process to a translator acting as an intermediary for two conversants who speak different languages, we would be arguing that the translator himself influenced the course of the conversation. …