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 a common type of epistemic modal operator?

  1. K

  2. B

  3. M

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

K is a common epistemic modal operator that represents knowledge.

Multiple choice

Which of the following is a common type of epistemic logic?

  1. Propositional epistemic logic

  2. First-order epistemic logic

  3. Modal epistemic logic

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

Propositional epistemic logic, first-order epistemic logic, and modal epistemic logic are all common types of epistemic logic.

Multiple choice

Which of the following is an example of an epistemic paradox?

  1. The lottery paradox

  2. The preface paradox

  3. The sorites paradox

  4. The liar paradox
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The preface paradox is an epistemic paradox that arises when an author claims to know something that they cannot know. For example, an author might claim to know that their book is free of errors, even though it is impossible for them to have checked every single statement in the book.

Multiple choice

What are the rules of logical inference?

  1. The rules of logical inference are based on the laws of thought

  2. The rules of logical inference are based on the structure of language

  3. The rules of logical inference are based on the customs and conventions of society

  4. The rules of logical inference are based on the personal preferences of the individual
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The rules of logical inference are based on the laws of thought. These laws are universal and apply to all rational beings, regardless of their language or culture.

Multiple choice

What is the fallacy of affirming the consequent?

  1. Assuming that the conclusion of an argument is true because the premises are true

  2. Assuming that the premises of an argument are true because the conclusion is true

  3. Assuming that a statement is true because it has been repeated many times

  4. Assuming that a statement is true because it is supported by authority
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The fallacy of affirming the consequent is assuming that the premises of an argument are true because the conclusion is true. This is a logical fallacy because the truth of the conclusion does not guarantee the truth of the premises.

Multiple choice

What is the fallacy of denying the antecedent?

  1. Assuming that the conclusion of an argument is false because the premises are false

  2. Assuming that the premises of an argument are false because the conclusion is false

  3. Assuming that a statement is false because it has been denied many times

  4. Assuming that a statement is false because it is opposed by authority
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The fallacy of denying the antecedent is assuming that the premises of an argument are false because the conclusion is false. This is a logical fallacy because the falsity of the conclusion does not guarantee the falsity of the premises.

Multiple choice

What is the difference between a disjunctive syllogism and a conjunctive syllogism?

  1. A disjunctive syllogism has two premises and one conclusion, while a conjunctive syllogism has one premise and two conclusions

  2. A disjunctive syllogism is based on the law of excluded middle, while a conjunctive syllogism is based on the law of non-contradiction

  3. A disjunctive syllogism is valid if one of the premises is true, while a conjunctive syllogism is valid if both premises are true

  4. A disjunctive syllogism is sound if the conclusion is true, while a conjunctive syllogism is sound if both premises are true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A disjunctive syllogism has two premises and one conclusion, while a conjunctive syllogism has one premise and two conclusions. In a disjunctive syllogism, the premises are connected by the word "or". In a conjunctive syllogism, the premise is connected by the word "and".

Multiple choice

Parmenides argued that reality is:

  1. One and unchanging

  2. Multiple and changing

  3. Both one and multiple

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Parmenides believed that reality is fundamentally one and unchanging, and that change and multiplicity are merely illusions.

Multiple choice

Which theory of truth argues that truth is a property of sentences rather than statements?

  1. Correspondence theory

  2. Coherence theory

  3. Pragmatic theory

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

The deflationary theory of truth maintains that truth is not a property of statements but rather a property of sentences, and that truth is simply a matter of using language correctly.

Multiple choice

The liar's paradox is a logical paradox that demonstrates the difficulties in defining truth. It involves a statement that asserts its own falsity. The paradox highlights the:

  1. Self-referential nature of language

  2. Incoherence of the concept of truth

  3. Arbitrariness of truth claims

  4. Subjectivity of truth
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The liar's paradox showcases the self-referential nature of language and the challenges in defining truth when statements refer to their own truth value.

Multiple choice

Which of the following is a valid inference rule in PTL?

  1. From G(p -> q) and p, infer q

  2. From F(p & q), infer G(p)

  3. From X(p U q), infer F(q)

  4. From Y(p R q), infer G(q)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is a valid inference rule because if p holds forever and p implies q, then q must also hold forever.

Multiple choice

What is the semantics of the formula G(p -> q)?

  1. In every possible execution, p implies q

  2. In some possible execution, p implies q

  3. In every possible execution, p holds

  4. In some possible execution, q holds
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

G(p -> q) means that in every possible execution, if p holds then q also holds.

Multiple choice

Which of the following is a valid inference rule in PTL?

  1. From F(p & q), infer F(p)

  2. From G(p -> q), infer G(q)

  3. From X(p U q), infer X(q)

  4. From Y(p R q), infer Y(q)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is a valid inference rule because if p and q hold eventually, then p must also hold eventually.

Multiple choice

Which of the following is a valid inference rule in PTL?

  1. From G(p -> q) and p, infer q

  2. From F(p & q), infer G(p)

  3. From X(p U q), infer F(q)

  4. From Y(p R q), infer G(q)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is a valid inference rule because if p holds forever and p implies q, then q must also hold forever.

Multiple choice

What is the puzzle of the contingent a priori?

  1. The puzzle that arises from the fact that some statements that are necessarily true are also contingent.

  2. The puzzle that arises from the fact that some statements that are contingent are also necessarily true.

  3. The puzzle that arises from the fact that some statements that are true are also false.

  4. The puzzle that arises from the fact that some statements that are false are also true.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The puzzle of the contingent a priori arises from the fact that some statements that are necessarily true are also contingent, which challenges the traditional view that necessary truths are independent of experience.