Here's the scientific way to make a persuasive argument

It helps to have strength in numbers

A new study suggests that when it comes to changing other people's views, dialogue can help your cause—but too much back-and-forth can be damaging.

To analyze what makes an argument effective, researchers from Cornell University mined nearly two years of data from the online community Reddit's ChangeMyView forum, where people invite other community members to convince them that a view they hold is actually incorrect. When people are successfully convinced to change their view, they denote which forum member made the most compelling argument.

The best arguments

The researchers found that people on ChangeMyView tended to make calm, rational arguments. Still, the most successful arguments shared certain characteristics:

There's strength in numbers. The more people who argued a position, the more likely it was that opponents would change their view. Arguments that users posted first were more likely to be selected as those that changed a person's view.

Dialogue is good—to an extent. Some back-and-forth suggested an argument was gaining traction, the researchers say. But if the conversation went on too long, the odds of people changing their view dropped dramatically. After five rounds, the chances of a shift were essentially zero, the study says.

Detail helps. Longer arguments may be more effective because they "can be more explicit and convey more information," the authors write. But length on its own is not always helpful. Effective arguments tended to cite their sources, use different language than the original post, and hedge their wording.

The research also yielded insights into which words people use when they were persuadable. For instance, using first person pronouns such as "I" suggested that someone was open to other arguments, while words like "anyone" suggested the opposite.

There are limits to the study. For instance, posting to ChangeMyView suggests users are predisposed to being persuaded. Even so, the researchers note most people on ChangeMyView don't change their views at all (Swanson, "Wonkblog," Washington Post, 2/10; Basu, "Science of Us," New York Magazine, 2/11).

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