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 a deontic paradox?

  1. The paradox of obligation

  2. The paradox of permission

  3. The paradox of prohibition

  4. The paradox of choice
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A Correct answer
Explanation

The paradox of obligation is a deontic paradox that arises when an agent is faced with two or more conflicting obligations. For example, an agent may be obligated to keep a promise, but also obligated to tell the truth, and these two obligations may conflict in certain situations.

Multiple choice

Which of the following is an example of a paradox?

  1. The more you give, the more you receive.

  2. The more you learn, the more you realize how much you don't know.

  3. The more you love, the more you get hurt.

  4. The more you try, the harder it gets.
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A Correct answer
Explanation

A paradox is a figure of speech that seems contradictory or absurd, but actually contains a deeper truth.

Multiple choice

Which of the following is an example of epistemic closure?

  1. If you know that all crows are black, then you know that no crows are white.

  2. If you know that all dogs are mammals, then you know that all mammals are dogs.

  3. If you know that all apples are red, then you know that all fruits are red.

  4. If you know that all roses are red, then you know that all flowers are red.
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A Correct answer
Explanation

This is an example of epistemic closure because it is a logical implication of the premise that all crows are black.

Multiple choice

Which of the following is an example of the problem of induction?

  1. If you have seen a thousand black crows, you can conclude that all crows are black.

  2. If you have seen a thousand red apples, you can conclude that all apples are red.

  3. If you have seen a thousand white swans, you can conclude that all swans are white.

  4. If you have seen a thousand green leaves, you can conclude that all leaves are green.
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A Correct answer
Explanation

This is an example of the problem of induction because it is an inductive argument that cannot be justified by deductive arguments.

Multiple choice

Deductive reasoning is a fundamental skill used by detectives to solve mysteries. What is the essence of deductive reasoning?

  1. Drawing conclusions from a set of premises using logical rules

  2. Making assumptions based on personal beliefs and experiences

  3. Relying on intuition and gut feelings to reach conclusions

  4. Using trial and error to find solutions
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A Correct answer
Explanation

Deductive reasoning involves drawing conclusions from a set of premises using logical rules. It is a top-down approach where general statements are used to derive specific conclusions.

Multiple choice

What is the verification principle?

  1. The principle that a statement is meaningful only if it can be verified through observation or experiment.

  2. The principle that a statement is meaningful only if it is analytic.

  3. The principle that a statement is meaningful only if it is synthetic.

  4. The principle that a statement is meaningful only if it is a priori.
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A Correct answer
Explanation

The verification principle is the principle that a statement is meaningful only if it can be verified through observation or experiment. This principle was popular among logical positivists in the early 20th century. The verification principle has been criticized for being too narrow, as it would exclude many meaningful statements, such as statements about ethics and aesthetics.

Multiple choice

The sorites paradox is a paradox that arises from the concept of:

  1. Vagueness

  2. Infinity

  3. Contradiction

  4. Induction
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A Correct answer
Explanation

The sorites paradox is a paradox that arises from the fact that there is no clear boundary between what is true and what is false. For example, consider the statement "All men are mortal." If we start with a young man, we can all agree that he is mortal. But what about a man who is 90 years old? Is he still mortal? What about a man who is 100 years old? At what point does a man become immortal? The sorites paradox shows that there is no clear answer to this question.

Multiple choice

Which of the following is a common objection to the dialetheism theory?

  1. The law of non-contradiction

  2. The problem of induction

  3. The Münchhausen trilemma

  4. The sorites paradox
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A Correct answer
Explanation

The law of non-contradiction is a fundamental principle of logic that states that a statement cannot be both true and false at the same time. The dialetheism theory challenges the law of non-contradiction by allowing contradictions to be true. This has led to a number of objections to the dialetheism theory, one of the most common being that it is simply illogical.

Multiple choice

Which of the following is an example of a defeasible belief?

  1. The belief that the sun will rise tomorrow

  2. The belief that 2 + 2 = 4

  3. The belief that I am in pain

  4. The belief that I am sitting in a chair
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A Correct answer
Explanation

The belief that the sun will rise tomorrow is a defeasible belief because it is possible that the sun will not rise tomorrow, for example, if the Earth were to be destroyed by an asteroid.

Multiple choice

Which of the following is an example of an invariant belief?

  1. The belief that the sun will rise tomorrow

  2. The belief that 2 + 2 = 4

  3. The belief that I am in pain

  4. The belief that I am sitting in a chair
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The belief that 2 + 2 = 4 is an invariant belief because it is not possible for 2 + 2 to equal anything other than 4.

Multiple choice

Which of the following is an example of a contextual belief?

  1. The belief that the sun will rise tomorrow

  2. The belief that 2 + 2 = 4

  3. The belief that I am in pain

  4. The belief that I am sitting in a chair
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The belief that I am in pain is a contextual belief because it depends on the context in which it is acquired. For example, if I am dreaming, then I might believe that I am in pain, but this belief would not be justified because it is not based on any real evidence.

Multiple choice

What is the name of the indubitable truth that Descartes discovered through his method of doubt?

  1. Cogito ergo sum

  2. I think, therefore I am

  3. I exist, therefore I think

  4. I am, therefore I think
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A Correct answer
Explanation

Descartes' method of doubt led him to the indubitable truth expressed in the Latin phrase 'Cogito ergo sum', which means 'I think, therefore I am'.

Multiple choice

Which of the following is a propositional logic connective?

  1. And

  2. Or

  3. Not

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

Propositional logic connectives are used to connect propositions and form new propositions.

Multiple choice

What is the truth value of the proposition "(P ∧ Q) → R" when P is true, Q is false, and R is true?

  1. True

  2. False

  3. Indeterminate
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The truth value of a conditional proposition is false when the antecedent is true and the consequent is false.

Multiple choice

Which of the following is a valid logical argument?

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

  2. All dogs are mammals. Cats are not dogs. Therefore, cats are not mammals.

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

  4. None of the above
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A Correct answer
Explanation

A valid logical argument is an argument in which the conclusion follows logically from the premises.