Reasoning

Logic and Fallacies

1,716 Questions

Understand the fundamentals of propositional logic, logical inference rules, and paradoxes. This set includes identifying logical fallacies, including those found in classical Nyaya logic. Strong grasp of these concepts is crucial for scoring well in the reasoning sections of competitive tests.

Propositional logic modelsLogical inference rulesTypes of logical fallaciesParadoxes and contingent truthsNyaya logic concepts

Logic and Fallacies Questions

Multiple choice

Which of the following is an example of an inductive argument?

  1. All dogs are mammals.

  2. Therefore, all mammals are dogs.

  3. Some dogs are black.

  4. Therefore, all dogs are black.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Inductive arguments are based on evidence and experience, and they allow us to make generalizations.

Multiple choice

Which of the following is an example of a deductive argument?

  1. All dogs are mammals.

  2. Therefore, all mammals are dogs.

  3. Some dogs are black.

  4. Therefore, all dogs are black.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Deductive arguments are based on logic and reason, and they allow us to draw conclusions from premises.

Multiple choice

Which of the following is an example of a logical fallacy?

  1. Ad hominem

  2. Straw man

  3. False dichotomy

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All of the above are examples of logical fallacies.

Multiple choice

What is the Completeness Theorem in Model Theory?

  1. If a theory is consistent, then it has a model.

  2. If a theory is complete, then it has a model.

  3. If a theory is decidable, then it has a model.

  4. If a theory is satisfiable, then it has a model.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Completeness Theorem states that if a theory is consistent, then it has a model.

Multiple choice

Which of the following is a valid deductive argument?

  1. All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

  2. All dogs are mammals. Fido is a dog. Therefore, Fido is a mammal.

  3. All birds can fly. Penguins are birds. Therefore, penguins can fly.

  4. All roses are red. This flower is red. Therefore, this flower is a rose.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is a valid deductive argument because the conclusion is guaranteed to be true if the premises are true. The first premise states that all men are mortal, and the second premise states that Socrates is a man. Therefore, the conclusion that Socrates is mortal is guaranteed to be true.

Multiple choice

Which of the following is an example of a deductive argument?

  1. The sky is blue. Therefore, the grass is green.

  2. All dogs are mammals. Fido is a dog. Therefore, Fido is a mammal.

  3. I am feeling tired. Therefore, I should go to bed.

  4. The sun is shining. Therefore, it is daytime.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is an example of a deductive argument because the conclusion is guaranteed to be true if the premises are true. The first premise states that all dogs are mammals, and the second premise states that Fido is a dog. Therefore, the conclusion that Fido is a mammal is guaranteed to be true.

Multiple choice

Which of the following is an example of an inductive argument?

  1. All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

  2. All dogs are mammals. Fido is a dog. Therefore, Fido is a mammal.

  3. I have seen the sun rise every day for the past year. Therefore, the sun will rise tomorrow.

  4. I have flipped a coin 10 times and it has landed on heads each time. Therefore, the next time I flip the coin, it will land on heads.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is an example of an inductive argument because the conclusion is not guaranteed to be true even if the premises are true. The first premise states that I have seen the sun rise every day for the past year, and the second premise states that the sun will rise tomorrow. However, it is possible that the sun will not rise tomorrow, even though I have seen it rise every day for the past year.

Multiple choice

What is the fallacy of affirming the consequent?

  1. Assuming that the conclusion of an argument is true and then using that assumption to prove the premises.

  2. Assuming that the premises of an argument are true and then using that assumption to prove the conclusion.

  3. Assuming that one premise of an argument is true and then using that assumption to prove the other premise.

  4. Assuming that the opposite of the conclusion of an argument is true and then using that assumption to prove the premises.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The fallacy of affirming the consequent is a logical fallacy that occurs when someone assumes that the conclusion of an argument is true and then uses that assumption to prove the premises. This is a fallacy because the truth of the conclusion does not guarantee the truth of the premises.

Multiple choice

Which of the following is an example of the fallacy of affirming the consequent?

  1. If it is raining, then the streets are wet. The streets are wet. Therefore, it is raining.

  2. If I study hard, then I will get a good grade. I got a good grade. Therefore, I must have studied hard.

  3. If I eat chocolate, then I will get a headache. I have a headache. Therefore, I must have eaten chocolate.

  4. If I go to the beach, then I will see the ocean. I saw the ocean. Therefore, I must have gone to the beach.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is an example of the fallacy of affirming the consequent because the conclusion (it is raining) is assumed to be true and then used to prove the premise (the streets are wet). However, just because the streets are wet does not mean that it is raining. There could be other reasons why the streets are wet, such as someone washing their car.

Multiple choice

What is the fallacy of denying the antecedent?

  1. Assuming that the conclusion of an argument is false and then using that assumption to prove the premises.

  2. Assuming that the premises of an argument are false and then using that assumption to prove the conclusion.

  3. Assuming that one premise of an argument is false and then using that assumption to prove the other premise.

  4. Assuming that the opposite of the conclusion of an argument is false and then using that assumption to prove the premises.
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

The fallacy of denying the antecedent is a logical fallacy that occurs when someone assumes that the antecedent of a conditional statement is false and then uses that assumption to prove the consequent. This is a fallacy because the falsity of the antecedent does not guarantee the truth of the consequent.

Multiple choice

Which of the following is an example of the fallacy of denying the antecedent?

  1. If it is raining, then the streets are wet. It is not raining. Therefore, the streets are not wet.

  2. If I study hard, then I will get a good grade. I did not study hard. Therefore, I will not get a good grade.

  3. If I eat chocolate, then I will get a headache. I did not eat chocolate. Therefore, I will not get a headache.

  4. If I go to the beach, then I will see the ocean. I did not go to the beach. Therefore, I will not see the ocean.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is an example of the fallacy of denying the antecedent because the antecedent (it is raining) is assumed to be false and then used to prove the consequent (the streets are not wet). However, just because it is not raining does not mean that the streets are not wet. There could be other reasons why the streets are wet, such as someone washing their car.

Multiple choice

Which of the following is an example of a sound argument?

  1. All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

  2. All dogs are mammals. Fido is a dog. Therefore, Fido is a mammal.

  3. I have seen the sun rise every day for the past year. Therefore, the sun will rise tomorrow.

  4. I have flipped a coin 10 times and it has landed on heads each time. Therefore, the next time I flip the coin, it will land on heads.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is an example of a sound argument because it is both valid and has true premises. The first premise (all men are mortal) is true, and the second premise (Socrates is a man) is also true. Therefore, the conclusion (Socrates is mortal) is also true.

Multiple choice

Which of the following is an example of an inductive argument?

  1. All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

  2. All dogs are mammals. Fido is a dog. Therefore, Fido is a mammal.

  3. I have seen the sun rise every day for the past year. Therefore, the sun will rise tomorrow.

  4. I have flipped a coin 10 times and it has landed on heads each time. Therefore, the next time I flip the coin, it will land on heads.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is an example of an inductive argument because the conclusion is not guaranteed to be true even if the premises are true. The first premise states that I have seen the sun rise every day for the past year, and the second premise states that the sun will rise tomorrow. However, it is possible that the sun will not rise tomorrow, even though I have seen it rise every day for the past year.

Multiple choice

What is the fallacy of affirming the consequent?

  1. Assuming that the conclusion of an argument is true and then using that assumption to prove the premises.

  2. Assuming that the premises of an argument are true and then using that assumption to prove the conclusion.

  3. Assuming that one premise of an argument is true and then using that assumption to prove the other premise.

  4. Assuming that the opposite of the conclusion of an argument is true and then using that assumption to prove the premises.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The fallacy of affirming the consequent is a logical fallacy that occurs when someone assumes that the conclusion of an argument is true and then uses that assumption to prove the premises. This is a fallacy because the truth of the conclusion does not guarantee the truth of the premises.

Multiple choice

Which of the following is an example of the fallacy of affirming the consequent?

  1. If it is raining, then the streets are wet. The streets are wet. Therefore, it is raining.

  2. If I study hard, then I will get a good grade. I got a good grade. Therefore, I must have studied hard.

  3. If I eat chocolate, then I will get a headache. I have a headache. Therefore, I must have eaten chocolate.

  4. If I go to the beach, then I will see the ocean. I saw the ocean. Therefore, I must have gone to the beach.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is an example of the fallacy of affirming the consequent because the conclusion (it is raining) is assumed to be true and then used to prove the premise (the streets are wet). However, just because the streets are wet does not mean that it is raining. There could be other reasons why the streets are wet, such as someone washing their car.