I once had a disagreement with a colleague about a claim in a lab manual for undergraduates. About 10 seconds into the discussion, his instinctive reaction was

I once had a disagreement with a colleague about a claim in a lab manual for undergraduates. About 10 seconds into the discussion, his instinctive reaction was "Does the internet say that's right?" After speaking with the professor that teaches the class, his instinct was also to check that the internet says it's right before updating the lab manual. I had a simple argument based on a well-known formula, but ultimately it's the internet that decides whether it's right or not.