Why is persuasion so hard, even when you have facts on your side?

As a philosopher, I’m especially interested in persuasion – not just how to convince someone, but how to do it ethically, without manipulation. I’ve found that one of the deepest insights comes from the German philosopher Immanuel Kant, a focus of my research, who was born 300 years ago: April 22, 1724.

In his final book on ethics, “The Doctrine of Virtue,” Kant writes that each of us has a certain duty when we try to correct others’ beliefs. If we think they’re mistaken, we shouldn’t dismiss them as “absurdities” or “poor judgment,” he says, but must suppose that their views “contain some truth.”

What Kant is describing might sound like humility – just recognizing that other people often know things we don’t. But it goes beyond that.

This moral duty to find truth in others’ mistakes is based on helping the other person “preserve his respect for his own understanding,” Kant claims. In other words, even when we encounter obviously false points of view, morality calls on us to help the person we’re talking to maintain their self-respect – to find something reasonable in their views.

This advice can come across as patronizing, as though we were supposed to treat other adults like children with fragile egos. But I think Kant is onto something important here, and contemporary psychology can help us see it.

Imagine that you had to postpone lunch because of a meeting. With only 15 minutes to spare and a growling stomach, you leave to get a burrito.

On your way, however, you run into a colleague. “I’m glad to see you,” they say. “I’m hoping to change your mind about something from the meeting.”

In that scenario, your colleague has little chance of persuading you. Why? Well, you need food, and they’re getting in the way of you satisfying that need.

As psychologists of persuasion have long recognized, a key factor in persuasion is attention, and people don’t attend to persuasive arguments when they have more pressing needs – especially hunger, sleep and safety. But less obvious needs can also make people unpersuadable.

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