There is no such source of error as the pursuit of truth.

Nobody makes errors on the scale of a person certain they are onto something true. Ordinary carelessness produces small mistakes; conviction produces whole systems, and it recruits everything it meets as further evidence. The seriousness of the search is exactly what makes its errors so hard to see from the inside.

When you are most confident, that is the moment to ask what you would accept as disproof. Say it out loud in advance. Any pursuit with no answer to that question has stopped being an inquiry.