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

Which of following is a direct evidence?

  1. Evidence heard from some other person

  2. A person who personally has no knowledge

  3. A person who is having an opinion

  4. A person who has seen it

  5. /
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A person who has directly seen or heard is a direct evidence.

Multiple choice

Rights and duties are

  1. postulates

  2. correlatives

  3. opposites

  4. parallels

  5. None of above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(2) A right is the correlative of a relative duty, 'relative' in that is the duty to one or more persons other than oneself or the state; or as the correlative of a conditional duty, 'conditional' in that the possessor of the right may choose not to exercise it.

Multiple choice

An explanation of an observation.

  1. Hypothesis

  2. Inference

  3. Prediction

  4. Conclusion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An inference is a logical interpretation or explanation based on prior knowledge and observations. It goes beyond the raw observation itself.

Multiple choice validating statements proofs in mathematics mathematical reasoning maths

Name the technique used in the first step of the solution to the problem below :
Verify that 5 is irrational
Solution : Let us assume that 5 is rational

  1. Counter example

  2. Direct method

  3. By Contradiction

  4. Contrapositive method
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The proof technique that starts by assuming the negation of the statement to reach a contradiction is called proof by contradiction.

Multiple choice physics electronic devices boolean algebra digital electronics and logic gates logic gates

Which of the following is/are correctly matched to their respective statement?

  1. Distributive Law This law permits multiplying or factoring out of an expression.

  2. Double Negation Law This law allows removal of brackets from an expression and regrouping of the variables.

  3. Commutative Law The order of application of two separate terms is not important.

  4. Associative Law A term that is inverted twice is equal to the original term.
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation
According to the commutative Law,
$A+B=B+A$
$A.B=B.A$
Hence the order of application is not important.
According to the Associative Law,
$A+(B+C)=(A+B)+C$
$A.(B.C)=(A.B).C$
According to the Distributive Law,
$(A+B).(A+C)=A.A+A.C+B.A+B.C$
Hence, multiplying or factoring out is permitted.
Multiple choice mathematical modelling proof by contradiction similar triangles

Which of the following is the correct steps to take when proving a statement using proof by contradiction?

  1. 1) Assume that your statement is true.

    2) Show this is the case using definitions and theorems.

    3) State that the statement is true.

  2. 1) Assume your statement is true for a certain instance.

    2) Show that it is true in more than one instance.

    3) State that your statement must be true.

  3. 1) Assume your statement to be false.

    2) Proceed as you would in a direct proof.

    3) Come across a contradiction.

    4) Use the contradiction to state that your assumption of the statement being false can't be the case, so your statement must be true.

  4. None of the answers are correct.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Proof by contradiction can be used to prove any kind of statements.

Steps to be followed:
     $\rightarrow$ Assume the statement we want to prove to be false.
     $\rightarrow$ Then start proving from that statement. 
     $\rightarrow$ We end up seeing our assumption to be wrong.
     $\rightarrow$ Now we can conclude our statement to be true.