The ability to change one’s mind should never be underestimated. We all make mistakes, take the wrong path, and defend things which at the time seemed defensible only for you to be proven wrong at some later date. It is a crucial part of the scientific method: believe something for only so long as it’s supported by the evidence. When that support is no longer there, change your working hypothesis to one that is supported by the facts. Rinse and repeat and you’re a step closer to enlightenment.