Originally Posted by donkevlar

The Wizard only provides the Scarecrow with the ILLUSION of intelligence. All these three adventurers needed was the confidence to bring out their respective 'brains', 'heart' and 'courage' that they all had in the first place. The Scarecrow not knowing the Pyth. Theorem sends out a message that even those blessed with a miracle still must work hard to obtain knowledge.

Either that or the screenwriter didn't proofread.