Deduction

Deductive or Inductive?

____ A vase was found broken on the floor; some money had been taken out of the safe; and there were strange scratches on the wall. It therefore follows that someone obviously burglarized the place.

____ The Director of the National Park Service stated in an interview that vegetation in the parks is seriously threatened by air pollution. Therefore, it must be the case that park vegetation is indeed threatened by air pollution.

____ All humans are mortal and Socrates is human. Therefore, Socrates is mortal.

____ The fingerprints on the gun match those of the defendant. Therefore, the defendant must have handled the gun.

____ If my car is out of gas, then it won’t start. My car will start. Therefore, my car is not out of gas.

____ All previously observed polar bears have weighed less than 1,500 pounds. Therefore, all polar bears probably weigh less than 1,500 pounds.

____ The vast majority of popes have been Americans. Therefore, the next pope will most likely be an American.

____ Alice is older than Bob, and Bob is older than Carlos. Therefore, it must follow that Alice is older than Carlos.

____ If people are not informed about the workings of government, then they cannot vote intelligently. People are not informed about the government. Therefore, people cannot vote intelligently.

____ The bumper sticker says “Vote of Fred Collins for Sheriff.” The obvious conclusion is that Collins is the best man for the job.

____ Either the painting is a forgery or it’s worth a small fortune. Therefore, the painting is worth a small fortune, since it’s not a forgery.

____ The Earth has air, water, and life. We know that Mars has air and water. Therefore, Mars probably has life.

____ All the evidence in this trial suggests that Robert Ramirez is guilty of murder. Let’s face it: He’s probably guilty.

____ If r = 2, then s = 3; r = 2, therefore r + s = 5.

____ All dogs have flippers. All cats are dogs. Therefore, all cats have flippers.

Enthymemes

1. All puzzles are interesting things and all logic exercises are puzzles.

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2. All flammable things are unsafe things, so all explosives are unsafe things.

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3. All Christians are non-Muslims and all Baptists are Christians.

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4. That which has no parts cannot perish by dividing its parts. The soul has no parts.

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5. All liars are unbelievable and no unbelievable people are upright.

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6. This syllogism is valid, for all invalid syllogisms commit an illicit process.

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7. The soul through all her being is immortal, since that which is ever in motion is immortal.

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8. A metaphysical sentence is a sentence which expresses neither a tautology nor an empirical hypothesis. Tautologies and empirical hypotheses form the entire class of meaningful propositions.

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9. The sale of assault rifles in the U.S. has increased the risk of death and injury. Therefore, assault rifles should be banned.

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10. It is morally wrong to download a song without paying for it because stealing is wrong.

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11. Smoking is morally wrong because suicide is wrong.

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12. Everybody who is trying hard will succeed; therefore, Jones will not succeed.

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13. If you are well-mannered, then it means you had a good upbringing. And, Jones is well-mannered.

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14. If two things don’t share all the same properties, then they aren’t identical. The body has the property of divisibility whereas the mind does not.

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15. The universe has a cause because everything that begins to exist has a cause.