Reasoning

Logic and Fallacies

1,803 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

According to Devitt, what is the primary condition for a proposition to be true?

  1. The proposition must be consistent with other true propositions.

  2. The proposition must be believed by a majority of people.

  3. The proposition must correspond to an existing fact.

  4. The proposition must be useful in practice.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Devitt argues that truth is a matter of correspondence between propositions and facts. A proposition is true if and only if it corresponds to an existing fact.

Multiple choice

What is the role of quantifiers in predicate logic?

  1. To specify the number of objects or individuals that satisfy a given predicate.

  2. To restrict the domain of discourse to a specific set of objects or individuals.

  3. To introduce logical connectives between propositions.

  4. To serve as predicates that describe properties or relations between objects.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Quantifiers in predicate logic are used to specify the number of objects or individuals that satisfy a given predicate. The two main quantifiers are the universal quantifier (∀) and the existential quantifier (∃).

Multiple choice

What is the principle of universal instantiation in predicate logic?

  1. Any instance of a universally quantified formula is true.

  2. Any instance of an existentially quantified formula is false.

  3. Any closed formula is true.

  4. Any open formula is false.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of universal instantiation states that any instance of a universally quantified formula is true. This means that if a formula is true for all values of a variable, then it is true for any specific value of that variable.

Multiple choice

What is the principle of existential instantiation in predicate logic?

  1. Any instance of a universally quantified formula is true.

  2. Any instance of an existentially quantified formula is false.

  3. Any closed formula is true.

  4. Any open formula is false.
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

The principle of existential instantiation states that any instance of an existentially quantified formula is true. This means that if a formula is true for at least one value of a variable, then it is true for some specific value of that variable.

Multiple choice

What is the completeness theorem for predicate logic?

  1. Any formula that is true in all models is provable in predicate logic.

  2. Any formula that is provable in predicate logic is true in all models.

  3. Any formula that is true in some model is provable in predicate logic.

  4. Any formula that is provable in predicate logic is true in some model.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The completeness theorem for predicate logic states that any formula that is true in all models is provable in predicate logic. This means that if a formula is true in every possible interpretation, then there is a proof of that formula in predicate logic.

Multiple choice

What is the soundness theorem for predicate logic?

  1. Any formula that is true in all models is provable in predicate logic.

  2. Any formula that is provable in predicate logic is true in all models.

  3. Any formula that is true in some model is provable in predicate logic.

  4. Any formula that is provable in predicate logic is true in some model.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The soundness theorem for predicate logic states that any formula that is provable in predicate logic is true in all models. This means that if there is a proof of a formula in predicate logic, then that formula is true in every possible interpretation.

Multiple choice

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

  1. A disjunctive syllogism has two premises and a conclusion, and the premises are disjunctive statements, while a conjunctive syllogism has one premise and a conclusion, and the premise is a conjunctive statement.

  2. A disjunctive syllogism has one premise and a conclusion, and the premise is a disjunctive statement, while a conjunctive syllogism has two premises and a conclusion, and the premises are conjunctive statements.

  3. A disjunctive syllogism has two premises and a conclusion, and the premises are categorical statements, while a conjunctive syllogism has one premise and a conclusion, and the premise is a hypothetical statement.

  4. A disjunctive syllogism has one premise and a conclusion, and the premise is a categorical statement, while a conjunctive syllogism has two premises and a conclusion, and the premises are hypothetical statements.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A disjunctive syllogism is a syllogism that has two premises and a conclusion, and the premises are disjunctive statements. A conjunctive syllogism, on the other hand, is a syllogism that has one premise and a conclusion, and the premise is a conjunctive statement.

Multiple choice

What is the primary focus of predicate logic?

  1. The study of the relationship between subjects and predicates

  2. The study of the structure of arguments

  3. The study of the validity of syllogisms

  4. The study of the logical consequences of statements
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Predicate logic is a branch of logic that deals with the relationship between subjects and predicates in a proposition.

Multiple choice

Which of the following is a fundamental assumption of signal detection theory?

  1. Stimuli are detected perfectly.

  2. Stimuli are detected based on a comparison with a threshold.

  3. Stimuli are detected based on a comparison with a criterion.

  4. Stimuli are detected based on a comparison with a standard.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Signal detection theory assumes that stimuli are detected based on a comparison with a threshold. This threshold is a hypothetical boundary that separates stimuli that are detected from those that are not.

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

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.