This post is part of Polyarchy , an independent blog produced by the political reform program at New America , a Washington think tank devoted to developing new ideas and new voices.

The editorial board of the San Fransisco Chronicle is not happy. It recently endorsed London Breed in the June special election for mayor. Breed, a moderate, pro-business candidate, is currently neck and neck with Mark Leno, a more stalwart progressive. And to the great chagrin of the Chronicle, Leno and the third-place candidate, Jane Kim (also a more stalwart progressive) are now teaming up against Breed.

Last Thursday, the Chronicle published an editorial: “Jane Kim, Mark Leno try to game the system in SF mayor’s race.” It disparaged the Kim-Leno alliance as “gaming the city’s ranked-choice election rules in an unprecedented way.”

This is a silly criticism. All politicians “game” whatever system they operate in. The question is how?

But the criticism is also instructive. It opens up a way of thinking about how different electoral rules encourage different types of gamesmanship.

The curious case of the San Francisco mayoral election

Let’s back up a second. San Francisco is one of a handful of major American cities that use ranked-choice voting to elect a mayor. The San Francisco system works like this: When voters cast their ballot, they get to rank their top three choices for mayor. If one candidate has a straight-up majority, that candidate is the winner. If no candidate has a first-round majority, the last-place finisher is eliminated, and anybody who voted for that candidate gets their votes transferred to their second choice. This process repeats until one candidate gets a majority.

In the current mayoral election, the three leading candidates — Breed, Leno, and Kim — speak for different constituencies. Breed, 43, is African-American in a city where African Americans now make up only 4 percent of the electorate but is the most pro-business candidate and is endorsed by the Chinatown Neighborhood Association. Kim, 40, is a Korean American and a progressive focused on early childhood education and minimum wage. Leno, 66, began his career as an LGBTQ rights activist and, if elected, would be the first openly gay mayor of San Francisco. Like Kim, he has also run on a strongly progressive platform.

Polling is in flux, but both Leno and Breed pull support in the high 20s, while Kim is approaching 20 percent. In a straightforward plurality-winner election (whoever gets the most votes wins), San Francisco would likely elect a mayor with about 30 percent of support, leaving about two-thirds of city voters feeling like their candidate didn’t win. And candidates would all be incentivized to run divisive campaigns. This is how most cities run their elections.

Ranked-choice voting is different.

How politicians “game” ranked-choice voting is exactly how politics should work

To “game” the system in a simple plurality-winner election, the basic strategy involves mobilizing your base while trying to tear down competing candidates. This involves lots of scorched-earth negative campaigning.

To “game” the system in a ranked-choice voting election, the basic strategy is to try to appeal broadly and say, I’d like to be your first choice, but if I can’t be your first choice, I’d like to be your second choice. In ranked-choice voting, we’d expect soft alliances among candidates who realize that they’re both stronger through coalition building than they are by law-of-the-jungle campaigning — just like what Kim and Leno are doing.

Negative campaigning reduces trust in government and makes citizens feel less politically efficacious. It also appears to increase negative partisanship and hatred of the other party. More broadly, zero-sum campaigning may encourage more ruthless candidates when politics works far better with consensus-oriented candidates.

Ranked-choice voting generally improves civility of campaigning. Voters in cities with ranked-choice voting report that campaigns became less negative after ranked-choice systems went into place. Cities with ranked-choice voting also have higher voter turnout. (For a helpful overview of scholarly research on ranked-choice voting, I recommend this.)

To accuse politicians of trying to “game” a political system is a bit like accusing politicians of trying to win an election. What else are they going to do?

Like everyone else in the world, politicians plan strategy based on the rules of the game. And different rules incentivize different behaviors.

Here’s an aside to illustrate the point: If we turn our minds back to the 2016 GOP primary, we might remember a similar situation among a wide field of candidates. A narrow plurality of GOP primary voters supported Donald Trump; an overwhelming majority didn’t. Had the GOP primary used ranked-choice voting, it would have been much easier for non-Trump candidates to collaborate and work together to defeat Trump. Instead, the electoral incentives of a plurality-winner election allowed Trump to engage in an effective divide-and-conquer strategy.

Electoral rules shape electoral campaigns

So when we set up electoral systems, it’s pointless to ask whether politicians will game the system. Of course they will! That’s what politicians do. The question we need to ask is how they will game the system.

Electoral rules matter — they shape the way politicians campaign, which in turn shapes how we collectively process and understand political conflict.

Here’s the bottom line: In a plurality-winner election, campaigning is entirely zero-sum. It’s no wonder we see so much of our politics as a zero-sum, us-against-them battle then. That’s what the plurality-winner electoral rules reward.

In a ranked-choice voting system, by contrast, there are much stronger incentives for non-zero compromises and coalition building. In other words, what we’re seeing in San Francisco — two candidates working together — is exactly what ranked-choice voting incentivizes. And if we want to see more of it, we need to change the rules more widely to reward it.