You might assume winning arguments — over politics, a work project, or even where to eat — requires hours of researching data and rehearsing well-informed points.

Not necessarily, says Jonah Berger, a marketing professor at the University of Pennsylvania's Wharton School. Most people think changing minds requires "some version of pushing" with "more facts, more figures [and] more emotional appeals," but that method usually fails, he says.

"We spend a lot of time thinking, 'If the client didn't bite, my colleague didn't listen, or my spouse didn't hear me, let me tell them one more time,'" he tells CNBC Make It.

Repeating or adding more evidence to the same argument can actually end up hurting it. That's because people often dilute their stronger claims by adding weaker, less relevant ones, Niro Sivanathan, an organizational behavior professor at London Business School, told CNBC Make It in November.

So, instead of hearing your strongest points, the person you're hoping to convince may walk away with a shallower understanding of your argument.

"Less is more," Sivanathan said. "If you have just one key argument, be confident and put that on the table, rather than feeling the need to list many others."

How to change people's minds in 2 steps

Luckily, there's a simple, two-step fix.

First, instead of adding points to your argument, "identify the roadblocks and barriers" that prevent your perspective from connecting with others, Berger says. People often resist hearing a new argument because they're uncertain, want to counter argue, or it doesn't fit the norms of their social group.

Understanding your audience helps, but if you're trying to drive someone or a group into action quickly, assume they don't want to be told what to do, Berger says.

"Pushing, telling or just encouraging people to do something often makes them less likely to do it," Berger wrote in his 2020 book, "The Catalyst: How to Change Anyone's Mind." That's because "people like to feel they have control over their choices and actions."

Hence step two: Craft your argument in a way that gives the receiver a sense of agency, like they are reaching a new conclusion on their own, Berger says.

There are a few ways to do that, as Berger laid out in his book:

• Outline the different choices, like multiple kinds of restaurants or different policies.
• Ask questions, so you can better understand their perspective, or gently introduce your viewpoint. If you want to negotiate a raise, you could start by asking your boss, "How do you think my performance has been this year?" Then, follow up with, "Do you think people should be compensated for high performance?" Berger says.
• Acknowledge both of your perspectives by finding common ground, or noting your shared goals, values or experiences.

By and large, Berger says, it's less about what you say, and more about how you say it.

"We think more about the ideas we want to communicate than the words we use," Berger says. "That's a mistake. Subtle shifts in our language can have a really big impact."

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