In recorded human history, no set of political institutions have outlived those of the Venetian Republic. Founded in the ashes of the Roman Empire, it survived as an independent republic until it was captured by Napoleon in 1797. Throughout its existence, it displayed a remarkable degree of political stability; furthermore, it was a place of relative prosperity and a hub of Mediterranean trade. In the 17th century, the nominal wages of unskilled laborers in Venice were higher than anywhere else in Europe, with the exception of Spain, which was coping with the inflow of specie from the New World.

One reason for Venice’s political exceptionalism, according to the historian Thomas Madden, was that Venice “lacked inalienable land. Instead, it was a city of liquid wealth and commerce.” Mr. Madden, a professor of medieval history at St. Louis University, recently wrote an authoritative history of Venice, focusing in great detail on the political environment of the city-state.

Over time, intricate political institutions developed, which not only ensured peaceful transfers of power but also restricted the power of the executive and created a climate conducive to business. Because Venice had no land and no natural resources, there was no point in setting up extractive feudal institutions, which were pervasive in Europe at that time. Instead, its institutions emerged to protect commerce, rather than extract resources—although evidence suggests that the capture of the government by the merchants later contributed to the economic stagnation of the city-state.

At any rate, some of the quirks of the Venetian political system seem to be prescient institutional inventions. Probably the best illustration is the procedure used to elect the chief magistrate, the Doge, which combined several elements that might improve the functioning of our contemporary political systems.

On the morning after a Doge’s death the members of the “Maggior Consiglio,” the council representing the freemen of the city, convened to first select by lot 30 of its members older than 30 years, who were designated as “electors.” But if—perhaps by analogy to the U.S. Electoral College—you think that the 30 then simply elected the Doge, you’re mistaken.

Those 30 were reduced to 9 by lot. The 9 then designated a group of 40, each of whom needed 7 approval votes out of the 9 members of the committee. Back in the hall, with the entire Maggior Consiglio present, these 40 would be reduced by lot to 12. As before, the 12 would nominate 25 names, subject to approval by 9 members of the committee. In the hall, these 25 would be reduced to 9. In turn, the 9 nominated 5 names each, commanding the support of at least 7 members of the group. Those 45 would be reduced by lot to 11, and then nominate the 41 true electors of the Doge.

Only then would the real election begin. The 41 were kept isolated in the ducal palace until the Doge was elected. Each member of the “Quarantuno” could nominate a candidate. In the early years, a name would be picked at random, and a yes/​no vote would be held. This would be repeated until a candidate was found who had the support of 25 members. Later on, this sequential procedure was changed to simultaneous approval vote, where each member of the Quarantuno votes yes or no on each of the nominated candidates. The candidate with the highest number of votes would be elected as the new Doge, provided that he had the attained at least 25 yes votes.

The complex voting and randomization procedure was connected to a broader set of rules curbing electoral patronage, corruption, and factions. As Coggins and Perali put it,

Office holders were not permitted to succeed themselves, though many spent their careers moving from one office to another. No family was permitted more than one member on the Ducal Council or any significant nominating committee or administrative board. A nominee’s relatives were prohibited from voting in an election involving him. Campaigns were entirely forbidden; men were sought by offices rather than the other way round. Once elected to an office a person was required to serve, and a heavy fine was levied against those who declined.

While at first sight this electoral procedure seems needlessly complicated and whimsical, it had several desirable properties, which arguably contributed to its stability over time. It is not a stretch to imagine that our current political systems could be improved by emulating the following three features of Venetian political life.

Firstly, the elections of the Doge relied on an iteration of supermajority decisions. The consecutive votes required majorities ranging from 77.8 percent in the initial nomination by the committee of 9 to 61 percent in final election by the Quarantuno. Since Buchanan and Tullock, political economists tend to like supermajorities, because they make it more difficult to impose costs on minorities and curb winner-takes-all behavior.

Secondly, the element of randomness introduced into the election, as well as the complexity of the procedures, reduced the scope for strategic behavior and functioned as a truth-revealing mechanism. With the exception of the Quarantuno, there was no predictable link between the choices of consecutive committees and the outcome—the election of a particular candidate as a Doge. In other words, the electors acted as if behind a veil of ignorance and had little incentives to either misrepresent their preferences or to act in a narrow material interest.

Thirdly, at the final stage of the election process, approval voting was used. Political scientists have shown that, under plausible assumptions, approval voting encourages sincere voting, reflective of people’s true preferences. If one is allowed to cast votes for multiple candidates, there is little reason not to vote for one’s favorite candidate, even if one thinks that she has only a small chance of being elected. It is striking to see the Venetians stumble upon approval voting centuries ago before its desirable properties were documented by scholars—and indeed well before economists or political scientists started to think systematically about the implications of different decision-making rules.

According to Mr. Madden, Venetian institutions prevented both the rise of ambitious tyrants and mob rule. Regardless of whether one agrees with that assessment or not, the study of Venice’s peculiar political institutions is valuable for our thinking about reform of Western political institutions. True, Venice did not have an open political system and was certainly no libertarian paradise. Yet, at the very least, its example seems to strengthen, rather than weaken, the case for the increased use of supermajorities and truth-revealing mechanisms, possibly involving randomization and/​or approval voting.