# Benny, Denny, Kenny and Lenny: Who lies and who tells the truth?

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Each of Benny, Denny, Kenny and Lenny either always lies or always tells the truth.

• Benny claims that Denny is a liar.
• Lenny claims that Benny is a liar.
• Kenny claims that both Benny and Denny are liars.
• Kenny also claims that Lenny is a liar.

Which of them always lies and which of them always tells the truth?

Ok, so this is the key understanding that made this make sense.

Kenny says that both of Benny and Denny are liars. Because of Benny's statement that Denny is a liar, Benny and Denny will always have opposite truth values. If Benny is True then Denny is False and vise versa.

Which means

Kenny must be a liar. Which means he is lying when he says that Lenny is a liar. Thus Lenny is telling the truth when he says that Benny is a liar.

Thus the final outcome is

Lenny and Denny are the two truth tellers, and Kenny and Benny are the two liars.

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