301. And The clever go free 2012-1-20

This brainteaserr is "isomorphic" to #208 in Gary Gruber's The World's 200 Hardest Brain Teasers. The basic concept has been around for decades, but has faded from view. (See column three for more information about this book.)

The city jail was overcrowded. A judge ordered the jailer to move three prisoners to the nearby state prison. After consulting with the prison's warden, the jailer told the judge that the prison could take only two of his prisoners.

The judge said, "Then you'll have to release a prisoner. You decide which, and I don't care how you decide."

The jailer picked three prisoners at random, and had his guards blindfold them and bring them to the jail parking lot, strapped into wheel chairs, unable to see behind them.

He said to them, still blindfolded, "A guard is standing behind each of the three of you. Two of them, one of them, or none of them is blond. The others have black hair. I will remove your blindfolds, one of you at a time. If you can tell your guard's hair color, I will release you from jail to freedom by lunchtime. Otherwise, I will transfer you to state prison."

A guard whispered to the jailer.

The jailer said, "Smith, I hear that you are blind, so you don't have a chance to win this. We'll take you back to your cell."

Smith said, "I'd like to try, if I may go third."

The jailer said, "Okay." He walked over to Jones and removed his blindfold."

Jones looked in Smith's direction, then toward the other prisoner, Baker, then said, "I don't know my guard's hair color."

The jailer said, "Too bad." He walked over to Baker and removed his blindfold. "Soon, Baker said, "I don't know my guard's hair color."

The jailer was silent for a moment. He hadn't selected one for release and two for transfer. Before he could give another order, Smith said, I know my guard's hair color, and I can explain how.

What was his guard's hair color, and how did he know—being blind, and all?

 Answer