There is an enormous difference between being closed-minded and being credulous. A decent posture is to say that claims need to be backed up by evidence. It's striking that whenever paranormal or UFO claims are investigated, they turn out to be unreproducible. At the very least, this indicates that we have insufficient proof to grant credibility to any claims. It's true that all people, eminent scientists included, can resist new ideas and dismiss evidence, but over time this position becomes untenable for claims that are backed up by a substantial body of evidence. If we abandon the requirement for credible evidence, we return to a world of mere assertion, superstition, credulity, and ignorance.