[Guest]

Four brothers (three swindlecants and one honestant) are asked by their mother who ate the last cookie.

Andy said "Bob ate it!"

Bob said "Charlie ate it!"

Charlie said "Bob's lying!"

David said "Well it wasn't me!"

Who ate the cookie?

[HoustonHokie]

Four brothers (three swindlecants and one honestant) are asked by their mother who ate the last cookie.

Andy said "Bob ate it!" - false

Bob said "Charlie ate it!" - false

Charlie said "Bob's lying!" - true

David said "Well it wasn't me!" - false

Who ate the cookie?

David ate the cookie. Charlie is the honestant.

[unreality]

Four brothers (three swindlecants and one honestant) are asked by their mother who ate the last cookie.

Andy said "Bob ate it!"

Bob said "Charlie ate it!"

Charlie said "Bob's lying!"

David said "Well it wasn't me!"

Who ate the cookie?

Only one is telling the truth. If it's Andy, then Bob ate it, but it means Bob is telling the truth that Charlie ate it [contradiction]. Also it means David is lying, so it IS David. [contradiction]

If Bob is the truthteller, then Charlie ate it, but David must be lying so David ate it too [contradiction]

If Charlie told the truth, then Bob is lying, which checks out, and also means that Charlie DIDN'T eat it. As Andy must be a liar too, Bob didn't eat it, so it either has to be Andy or David. David must be lying when he says that it wasn't him, so the thief is David

Just to make sure, I'll check out what happens if David is the truthteller: Andy and Bob must both be liars, meaning Bob and Charlie aren't thieves. Charlie's a liar when he says that Bob is lying, so Bob must be telling the truth. Uber-contradiction [contradiction]

Thus Charlie is the Honestant, and David stole the cookie

~~~

Another way you could prove this is analyzing just Charlie's statement. He says that Bob is lying. Thus, if Charlie is lying, Bob is telling the truth, and if Charlie tells the truth, then Bob lies. Because only one person can tell the truth, and either way either Bob or Charlie tells the truth, it must be either of those two. However, if Bob is the truthteller, then Charlie is guilty... but if David is lying too (which he would be), then David is the thief too. Thus the only noncontradiction comes from Charlie telling the truth and David stealing

[Guest]

Four brothers (three swindlecants and one honestant) are asked by their mother who ate the last cookie.

Andy said "Bob ate it!" - false

Bob said "Charlie ate it!" - false

Charlie said "Bob's lying!" - true

David said "Well it wasn't me!" - false

Who ate the cookie?

David ate the cookie. Charlie is the honestant.

Well done. You deserve a cookie!

[Guest]

Forget the cookie! Can I have Charlie instead? It's damn near impossible to find an honest man!

[Guest]

David?

Four brothers (three swindlecants and one honestant) are asked by their mother who ate the last cookie.

Andy said "Bob ate it!"

Bob said "Charlie ate it!"

Charlie said "Bob's lying!"

David said "Well it wasn't me!"

Who ate the cookie?

Edited November 27, 2008 by pratt0909