There are numerous cognitive biases at play in our lives, but one that I have been exposed to recently (and likely caused) is something known as the Backfire Effect.
The Belief: Our common perception is that when we believe strongly in something, and new facts/data are presented that challenge those beliefs, we (as rational people) act rationally and adjust our viewpoints.
The Reality: The truth is when people have strongly held beliefs, and data/evidence is presented to the contrary, the human reaction is to “double down” and strengthen the initial belief. We concoct new evidence, make up new theories, and even vilify the person delivering the new data as an unhinged lunatic.
What you can do: I would say to first recognize this cognitive bias in ourselves, and fight our hardest against it. One idea is to begin by evaluating/gathering your own strongly held beliefs. Just do some soul searching and find those things you feel very, very strongly about.
When you know what those things are, be as vigilante as you can be about how you engage with those that disagree with you. Your job is to never allow yourself to silence those with dissenting viewpoints. This is incredibly challenging, but give those people more space to discuss their views. Ask clarifying questions about their positions, and build empathy for the other person and how they arrived at their conclusions. This helps you build trust. And if you trust their intentions, you will find that you will be more willing to accept new data and adjust your beliefs.
Lastly (and most interesting of all) please recognize that any selling you do in this moment will only incite the Backfire Effect for that person.
They also need to trust you. You can enhance this trust if you work hard to avoid attempting to degrade their position while improving yours without first “making it safe”. One way is to ensure that they know that they were likely right at one point given the data or situation they were in.
If we can manage to control our own emotions in these situations, be open to alternate views, build empathy and trust, the outcomes (and our beliefs) will get challenged over time, and we will improve.