The idea that only weird loners believe in conspiracy theories is a misconception. Knowing how easily conspiracy theories spread these days, it should be no surprise that normal people can get caught up in them. Make sure to stay calm, and don’t assume that the other person has gone completely crazy.
Don’t cast blame
Try to avoid words like ‘conspiracy theorist’ and ‘conspiracy theory’. This way you avoid labelling the other person and you can start the conversation in a positive manner. Also avoid saying things like “I can’t understand how you could believe this” or “What you’re saying is nonsense”.
Try to understand
Try to put yourself in the other person’s shoes, even if you are 100% convinced you are right. The best way to do so is by asking critical but open questions: “What makes you so sure of that?” or “What evidence have you found for that?”. You don’t immediately need to bombard the other person with counterarguments.
Explain your own thoughts
Has your conversation partner been able to tell their story? Now you can explain how you feel about the matter. Use the first person, and make sure to cite objective arguments and sources: “I wonder if that can be right, because I saw on the news that …” or “I read on a fact-checking website that …”. It’s fine to indicate that you don’t believe the story. You need to respect the conspiracy theorist’s convictions, but they also need to respect yours.
End the conversation on time
You won’t always be able to convince a conspiracy theorist that they’re wrong in one conversation. Try to sense when it’s time to wrap up the conversation, for example when you’ve used up all your arguments or when things get heated. Let the subject rest, and pick it up again next time if the other person initiates the conversation.