Logic and Truth

Premise 1: Some people are doctors.
Premise 2: John is a person.

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Conclusion: Therefore, John is a doctor.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: All squares are rectangles.
Premise 2: This shape is a rectangle (assume this is true).

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Conclusion: Therefore, this shape is a square.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: All fish swim.
Premise 2: Dolphins swim.

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Conclusion: Therefore, dolphins are fish.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: All cats are mammals.
Premise 2: All dogs are mammals.

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Conclusion: Therefore, all cats are dogs.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: Some cars are red.
Premise 2: My car is blue.

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Conclusion: Therefore, my car is faster than red cars.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: All mammals have a backbone.
Premise 2: A whale is a mammal.

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Conclusion: Therefore, a whale has a backbone.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: All spiders have eight legs.
Premise 2: A black widow is a spider. (this is true)

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Conclusion: Therefore, a black widow has eight legs.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: If a number is even, it is divisible by 2.
Premise 2: 8 is an even number.

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Conclusion: Therefore, 8 is divisible by 2.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: If it rains, the ground gets wet.
Premise 2: It is raining. (assume this is true)

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Conclusion: Therefore, the ground is getting wet.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic

Premise 1: All planets orbit a star. (this is true)
Premise 2: Earth is a planet.

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Conclusion: Therefore, Earth orbits a star.

• All true premises and bad logic

• All true premises and good logic

• One or more false premises and good logic

• One or more false premises and bad logic