“Why do people believe strange things like UFOs, faces on Mars, crop circles, fake bomb detectors and so on? How can we even begin to understand the human tendency to believe in nonsense? Scientific skepticism (often just called “skepticism”) is a method to evaluate questionable claims with rational argument and scientific evidence.
One prominent reason that might help explain why people believe odd things without evidence is that humans are not perfectly rational, but have a brain that is good at doing a lot of things but also vulnerable to having its quirks exploited by charlatans and quacks. These quirks are known as heuristics and biases. The former are quick and dirty tricks to evaluating a ton of information and reach a decent results (more or less cognitive rules of thumb), whereas biases are systematic deviations from perfect rationality such as downplaying disconfirming evidence or making superficially plausible, yet statistically invalid arguments.”