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 logical connective is often used to express constructive disjunction in Intuitionistic Logic?

  1. ∨ (disjunction)

  2. ∧ (conjunction)

  3. → (implication)

  4. ¬ (negation)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In Intuitionistic Logic, the disjunction connective (∨) is often interpreted as constructive disjunction, where at least one of the disjuncts can be constructively proven.

Multiple choice

Which of the following is a valid inference rule in Intuitionistic Logic?

  1. Modus Tollens

  2. Hypothetical Syllogism

  3. Disjunctive Syllogism

  4. Constructive Dilemma
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Constructive Dilemma (P → Q, R → S, P ∨ R ⊢ Q ∨ S) is a valid inference rule in Intuitionistic Logic, allowing you to infer Q ∨ S from P → Q, R → S, and P ∨ R.

Multiple choice

Which of the following statements is an example of a deontic statement?

  1. The sky is blue.

  2. You should tell the truth.

  3. 2 + 2 = 4.

  4. All dogs are mammals.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A deontic statement expresses a moral obligation, permission, or prohibition. In this case, the statement "You should tell the truth" expresses a moral obligation.

Multiple choice

Which of the following is a valid inference in deontic logic?

  1. If it is obligatory to help others, then it is permitted to help others.

  2. If it is permitted to lie, then it is obligatory to lie.

  3. If it is prohibited to steal, then it is obligatory to steal.

  4. If it is indifferent to vote, then it is obligatory to vote.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In deontic logic, if an action is obligatory, then it is also permitted. This is because an obligatory action is one that is morally required or commanded, and it would be contradictory to say that an action is both obligatory and prohibited.

Multiple choice

What is the logical relationship between "It is obligatory to tell the truth" and "It is permitted to lie"?

  1. They are logically equivalent.

  2. They are logically contradictory.

  3. They are logically independent.

  4. They are logically consistent.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The statements "It is obligatory to tell the truth" and "It is permitted to lie" are logically contradictory because they express opposite moral evaluations of the same action. It is impossible for both statements to be true at the same time.

Multiple choice

Which of the following is an example of a normative statement?

  1. The Earth revolves around the Sun.

  2. You should be honest with your friends.

  3. The boiling point of water is 100 degrees Celsius.

  4. All triangles have three sides.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A normative statement expresses a moral or ethical judgment about what ought to be or what is good or bad. In this case, the statement "You should be honest with your friends" expresses a moral judgment about what is the right thing to do.

Multiple choice

Which of the following is a valid inference in deontic logic?

  1. If it is obligatory to help others, then it is permitted to help others.

  2. If it is permitted to lie, then it is obligatory to lie.

  3. If it is prohibited to steal, then it is obligatory to steal.

  4. If it is indifferent to vote, then it is obligatory to vote.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In deontic logic, if an action is obligatory, then it is also permitted. This is because an obligatory action is one that is morally required or commanded, and it would be contradictory to say that an action is both obligatory and prohibited.

Multiple choice

What is the logical relationship between "It is obligatory to tell the truth" and "It is permitted to lie"?

  1. They are logically equivalent.

  2. They are logically contradictory.

  3. They are logically independent.

  4. They are logically consistent.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The statements "It is obligatory to tell the truth" and "It is permitted to lie" are logically contradictory because they express opposite moral evaluations of the same action. It is impossible for both statements to be true at the same time.

Multiple choice

Which of the following is an example of a normative statement?

  1. The Earth revolves around the Sun.

  2. You should be honest with your friends.

  3. The boiling point of water is 100 degrees Celsius.

  4. All triangles have three sides.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A normative statement expresses a moral or ethical judgment about what ought to be or what is good or bad. In this case, the statement "You should be honest with your friends" expresses a moral judgment about what is the right thing to do.

Multiple choice

Which of the following is a valid inference in deontic logic?

  1. If it is obligatory to help others, then it is permitted to help others.

  2. If it is permitted to lie, then it is obligatory to lie.

  3. If it is prohibited to steal, then it is obligatory to steal.

  4. If it is indifferent to vote, then it is obligatory to vote.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In deontic logic, if an action is obligatory, then it is also permitted. This is because an obligatory action is one that is morally required or commanded, and it would be contradictory to say that an action is both obligatory and prohibited.

Multiple choice

What is the logical relationship between "It is obligatory to tell the truth" and "It is permitted to lie"?

  1. They are logically equivalent.

  2. They are logically contradictory.

  3. They are logically independent.

  4. They are logically consistent.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The statements "It is obligatory to tell the truth" and "It is permitted to lie" are logically contradictory because they express opposite moral evaluations of the same action. It is impossible for both statements to be true at the same time.

Multiple choice

Which of the following is an example of a normative statement?

  1. The Earth revolves around the Sun.

  2. You should be honest with your friends.

  3. The boiling point of water is 100 degrees Celsius.

  4. All triangles have three sides.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A normative statement expresses a moral or ethical judgment about what ought to be or what is good or bad. In this case, the statement "You should be honest with your friends" expresses a moral judgment about what is the right thing to do.

Multiple choice

What is the name of the fallacy in Indian logic that occurs when a conclusion is drawn from two premises that are not logically connected?

  1. Hetvabhasa

  2. Sadhana

  3. Vyapti

  4. Anumana
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hetvabhasa is a fallacy in Indian logic that occurs when a conclusion is drawn from two premises that are not logically connected. It is also known as a fallacy of the middle term.

Multiple choice

Which of the following is a type of fallacy in Indian logic that occurs when a conclusion is drawn from a premise that is not supported by evidence?

  1. Adhyavasaya

  2. Vyapti

  3. Hetvabhasa

  4. Sadhana
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Adhyavasaya is a type of fallacy in Indian logic that occurs when a conclusion is drawn from a premise that is not supported by evidence. It is also known as a fallacy of hasty generalization.

Multiple choice

Which of the following is a type of inference in Indian logic that involves drawing a conclusion from a single premise?

  1. Anumana

  2. Vyapti

  3. Hetvabhasa

  4. Kevalanvayi
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Kevalanvayi is a type of inference in Indian logic that involves drawing a conclusion from a single premise. It is based on the principle that if A is always associated with B, and A is present, then B must also be present.