What Game Theory Tells Us About Donald Trump

Hillary Clinton is tasked with outwitting the human equivalent of a four-line computer program

Game theorists have studied the counter-punching strategy Donald Trump is now known for. Credit: Joe Raedle/Getty

Donald Trump likes to brag about his negotiating skills, but for a tough negotiator, he's awfully easy to manipulate. There are two types of people in Trumpland: those who are nice to Donald, and those who are not nice to Donald. If you flatter Trump, he'll treat you well. If you criticize him, he'll retaliate. "I'm a counter-puncher," he once told CNN.

So to win Trump's favor, just say something sweet about him; Vladimir Putin praised him last December, and Trump has been preening over the compliment ever since. And to deliberately draw Trump's fire, say something nasty about him; last week Elizabeth Warren called him a bully and a loser, which dragged him into a distracting and unpresidential tweetfight with someone who is not his opponent.

Game theorists have studied the counter-punching strategy Trump is now known for. In 1980, political scientist Robert Axelrod invited colleagues to design computer programs that would compete against each other in a contest of cooperation and betrayal known as the prisoner's dilemma. In the game, two criminals are offered immunity to turn the other in. If only one snitches, he goes free, and the other receives a five-year sentence. If both inform on each other, they get four years. If neither talks, they get two years. The game is played repeatedly, so each player faces the same choice over and over, whether to be a nice guy who protects his accomplice or a nasty one who betrays him.

One of the tournament contestants was a four-line computer program called Tit for Tat. Its strategy was simple: Whenever the other player snitched, Tit for Tat retaliated by informing on that player in the next round. Whenever the other player kept silent, Tit for Tat returned the favor by staying mum the next round. By maximizing cooperation with "nice" players and punishing "nasty" ones, Tit for Tat outmaneuvered its opponents and won the tournament.

This election cycle, we have Tit for Trump. From politicians to journalists to pollsters, Trump is quick to praise anyone who speaks favorably of him, and even quicker to denigrate those who don't. "If I am treated unfairly," he once warned BuzzFeed, "I will go after that reporter." Referring to his Republican primary opponents, he told CNN, "I thought these people were all fine, and they came after me, and then I had to go after them."

So far, the tit-for-tat strategy seems to have paid off. Trump's reputation for ferocious counterattacks helped dissuade opponents from tangling with him early in the Republican primary. Other GOP leaders refrained from criticizing him out of fear that he would retaliate against "unfair" treatment by launching a third-party campaign. As Trump's opponents fell behind, they were finally forced to engage. One by one, Lindsey Graham, Rand Paul, Jeb Bush, Marco Rubio and Ted Cruz entered Trump's tit-for-tat universe and went down under a hail of insults.

Unfortunately for Trump, not all adversaries are as hapless as the Republican presidential hopefuls. Unlike game-theory automatons, humans can identify the tit-for-tat strategy and use the knowledge to manipulate their opponents. That is Trump's weak spot, a dangerous one if he were to become president. Savvy operators like Putin would soothe Trump with praise while quietly undercutting American interests. Conversely, adversaries who wanted to drag America into diplomatic or military quarrels could provoke Trump's fury with well-placed barbs.

Hillary Clinton could also exploit Trump's weakness to defeat him, but she'll have to be clever about it. She can't entirely take the high road, as Jeb Bush originally attempted; leaving Trump's insults unanswered would make her look weak and allow him to define her. On the other hand, she cannot win a tit-for-tat insult war with him. At best, the two of them would fall into what game theorists call a "death spiral," wherein both players repeatedly counterattack and obliterate each other. Trump, with less gravitas to lose, would come out ahead.

There is another way. Trump's biggest mistake during the primary was to feud with people who were not running against him. His battle with Fox News host Megyn Kelly alienated women voters and caused him to miss an important debate. His denigration of John McCain's war record may not have destroyed his candidacy, as some pundits predicted, but it certainly didn't help. And calling Iowa voters "stupid" after Ben Carson surged in the polls was, itself, stupid.

Clinton can exploit Trump's propensity to retaliate against anyone who crosses him by deploying surrogates to batter him with a fusillade of insults. If Trump were smart, he would ignore them and focus on Clinton, but his reaction to Elizabeth Warren's tweets suggests he cannot resist the urge to counterpunch, even when it doesn't serve his interests. With every over-the-top smackdown, he will distract voters from his message and deflate whatever presidential gravitas he manages to muster.

Under this theory, the most effective Trump provocateurs would be popular public figures — politicians, journalists, even celebrities — who aren't afraid to hit him hard and draw his fire. Most important is Clinton's vice presidential choice. She might do well to pick a brawler who is willing to spend the next six months in an ugly slugfest with Trump, ideally a woman or minority who will draw out Trump's bigotry and provoke him into alienating even more voters. While Trump tangles with Clinton's surrogates, hurling epithets and lunging in every direction, she could safely fly above the storm, looking presidential and prudent. The more she played him, the less he'd look like a tough guy, and the more he'd look like a dangerous and erratic chauvinist who mistakes flattery for admiration and jumps at shadows while his opponents run circles around him.

Both Clinton's advantage and disadvantage is that she's tasked with outwitting the human equivalent of a four-line computer program.

Donald Trump has no qualms taking to his favorite medium to insult people. Watch his meanest Twitter insults here.