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 logical fallacy that can be used to attack the argument from evil?

  1. Appeal to ignorance

  2. Straw man

  3. Ad hominem

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

A false dilemma is a logical fallacy that presents only two options when in reality there are more. In the context of the argument from evil, a false dilemma might be to say that either God is all-powerful and allows evil to exist, or he is not all-powerful and cannot prevent evil from existing.

Multiple choice

What is a paradox?

  1. A statement that seems contradictory but is actually true

  2. A statement that is obviously false

  3. A statement that is ambiguous

  4. A statement that is nonsensical
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A paradox is a statement that appears to be self-contradictory or absurd, but in reality expresses a truth.

Multiple choice

Which of the following is NOT a type of condition?

  1. Express condition

  2. Implied condition

  3. Constructive condition

  4. Concurrent condition
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

Constructive conditions are not a type of condition. They are a legal doctrine that allows a party to terminate a contract if the other party has substantially breached the contract.

Multiple choice

Which of the following is a propositional variable?

  1. A

  2. B

  3. C

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

A propositional variable is a letter that represents a proposition, which is a statement that is either true or false.

Multiple choice

Which of the following is a logical connective?

  1. And

  2. Or

  3. Not

  4. If-then
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A logical connective is a word or symbol that connects two or more propositions to form a compound proposition.

Multiple choice

What is the truth value of the compound proposition "(P ∧ Q) ∨ ¬R" if P is true, Q is false, and R is true?

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using the truth table for the logical connectives, we can determine that the compound proposition is true.

Multiple choice

Which of the following is a valid logical argument?

  1. If it is raining, then the ground is wet.

  2. The ground is wet, therefore it is raining.

  3. If it is raining, then the sky is blue.

  4. The sky is blue, therefore it is raining.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

Multiple choice

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

  1. All men are mortal.

  2. Socrates is a man.

  3. Therefore, Socrates is mortal.

  4. All dogs are mammals.

  5. Cats are not dogs.

  6. Therefore, cats are not mammals.
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

This is a sound logical argument because the premises are true and the conclusion follows logically from the premises.

Multiple choice

Which of the following is an example of an unsound logical argument?

  1. All birds can fly.

  2. Penguins are birds.

  3. Therefore, penguins can fly.

  4. All fruits contain seeds.

  5. Tomatoes are fruits.

  6. Therefore, tomatoes contain seeds.
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

This is an unsound logical argument because the premises are true but the conclusion does not follow logically from the premises.

Multiple choice

What is the contrapositive of the proposition "If it is raining, then the ground is wet"?

  1. If the ground is wet, then it is raining.

  2. If it is not raining, then the ground is not wet.

  3. If the ground is not wet, then it is not raining.

  4. If it is raining, then the ground is not wet.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The contrapositive of a proposition is formed by negating both the hypothesis and the conclusion, and then switching them.

Multiple choice

Which of the following is a tautology?

  1. (P ∨ ¬P)

  2. (P ∧ ¬P)

  3. (P → Q) ∨ (¬P → Q)

  4. (P → Q) ∧ (¬P → ¬Q)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A tautology is a compound proposition that is always true, regardless of the truth values of its component propositions.

Multiple choice

Which of the following is a contradiction?

  1. (P ∨ ¬P)

  2. (P ∧ ¬P)

  3. (P → Q) ∨ (¬P → Q)

  4. (P → Q) ∧ (¬P → ¬Q)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A contradiction is a compound proposition that is always false, regardless of the truth values of its component propositions.

Multiple choice

What is the law of detachment?

  1. If P → Q and P, then Q.

  2. If P → Q and ¬Q, then ¬P.

  3. If P ∨ Q and P, then Q.

  4. If P ∨ Q and ¬P, then Q.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The law of detachment is a rule of inference that allows us to conclude Q from P → Q and P.

Multiple choice

What is the law of syllogism?

  1. If P → Q and Q → R, then P → R.

  2. If P → Q and ¬Q, then ¬P.

  3. If P ∨ Q and P, then Q.

  4. If P ∨ Q and ¬P, then Q.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The law of syllogism is a rule of inference that allows us to conclude P → R from P → Q and Q → R.

Multiple choice

Which of the following is an example of a spatial entity?

  1. A table

  2. A thought

  3. A number

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

A table is a spatial entity because it has a definite location in space and can be measured.