Philosophers and Sophists

Philosophers & Sophists

Credit: Raymond Smullyan, What's the name of this book? (1972)

A very special island

We find ourselves on a very special island, back in Antiquity.

There are only two types of people on this island.

A very special island

We find ourselves on a very special island, back in Antiquity.

There are only two types of people on this island.

• Philosophers: who always speak the truth

• Sophists: who always lie

​Zeno says: "At least one of use is a sophist."

Crito says nothing

Dropdown

Assume Zeno is a ​

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. Then what he said -at least one of them is a sophist- is true.

But sophists always ​​

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. Thus, as a sophist, Zeno could not have uttered a correct sentence. Our assumption is therefore wrong and Zeno is a ​ ​

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.

As such, he always ​

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​ . Therefore, one of them is a sophist. Since ​

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​ is a philosopher, the other is bound to be a sophist.

Problem #1

​Zeno says: "We are both sophists."

Crito says nothing

Multiple Choice

Which statement is true?

• Zeno and Crito are sophists

• Zeno is philosopher, Crito is sophist

• Zeno is sophist, Crito is philosopher.

• Zeno and Crito are philosophers.

​Zeno says: "We are both sophists."

Crito says nothing

​sophist

​philosopher

Problem #2

​Zeno says: "We are a different kind."

Crito says "We are the same kind."

Multiple Choice

Which statement is true?

• Zeno and Crito are sophists

• Zeno is philosopher, Crito is sophist

• Zeno is sophist, Crito is philosopher.

• Zeno and Crito are philosophers.

​Zeno says: "We are a different kind."

Crito says "We are the same kind."

​philosopher

​sophist

Problem #3

​Zeno says: "Crito is a sophist."

Crito says "Zeno and I are philosophers."

Multiple Choice

Which statement is true?

• Zeno and Crito are sophists

• Zeno is philosopher, Crito is sophist

• Zeno is sophist, Crito is philosopher.

• Zeno and Crito are philosophers.

Problem #4

​Zeno says: "Crito and I are both philosophers or both sophists."

Crito says "We are the same kind."

Multiple Choice

Which statement is true?

• Zeno and Crito are sophists

• Zeno is philosopher, Crito is sophist

• Zeno is sophist, Crito is philosopher.

• Zeno and Crito are philosophers.