Shawn Spencer

... is psychic!

No. 

Really.

He's psychic. 

More formally, Shawn is the lead psychic for the Santa Barbara Police Department, in addition to running his own private psychic investigation firm, which he cheerfully calls Psych. He's known to be eccentric and easily distracted, but he frequently uses his gifts for good: he's cracked so many cases for the police he's almost ready to stop counting (25 and still going strong!) that it's just ridiculous. 

In truth... he's not really psychic, he's just incredibly smart with an amazing eye for detail.  He'll 'divine' things using the flimsiest of reasoning. He keeps up the psychic facade for a lot of reasons, partly to maintain credibility with the police. Mostly for his own amusement.

He'll never, ever admit that he's a fake, except to Gus, his best friend, who knows it anyway.