Logic 2 PYQs (2022-2023)

 

Q.1 Answer the following in one or two sentences (Any Six)

a) State Aristotle's Dictum and its meaning.
Ans: Aristotle's Dictum states that "What is affirmed or denied of a whole class may be affirmed or denied of everything contained in that class." It means that if a predicate belongs to a class, it belongs to all its members.

b) Give the Symbolic form of rule of De Morgan's Law.
Ans: The symbolic forms are:
1) ¬(p ∧ q) ≡ (¬p ∨ ¬q)
2) ¬(p ∨ q) ≡ (¬p ∧ ¬q)

c) State the Rule of Material Implication. Give Symbolic form.
Ans: The Rule of Material Implication states that “If p implies q, then either q is true or p is false.”
Symbolic form: (p → q) ≡ (¬p ∨ q)

d) Define the fallacy of Equivocation.
Ans: The fallacy of Equivocation occurs when a word or expression is used in different senses within the same argument, causing confusion and invalid reasoning.

e) State any new impediments to good reasoning.
Ans: Impediments to good reasoning include prejudice, bias, emotional influence, ignorance, and use of ambiguous language.

f) What is the meaning of legal maxim “Vis Major”?
Ans: The term “Vis Major” means an act of God or irresistible force — something beyond human control that prevents fulfillment of an obligation.

g) State Mill's view of cause.
Ans: According to J. S. Mill, a cause is “the sum total of conditions which are both positive and negative, that together produce the effect.”

h) Define Direct Reduction.
Ans: Direct Reduction is a process of reducing a syllogism of a particular figure to the first figure by using simple conversion or transposition of premises.

i) Define Hypothesis.
Ans: A hypothesis is a provisional or tentative explanation of facts which serves as a basis for further investigation or verification.

j) What is Crucial Experiment?
Ans: A Crucial Experiment is an experiment designed to decide between two or more competing hypotheses by confirming one and disproving the others.

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Q.2 Write short notes on any three

a) Modus Ponens
Ans: Modus Ponens is a valid deductive rule of inference meaning “the way of affirming.” Its form is:
If p → q and p is true, then q must be true.
Symbolically: p → q, p ∴ q

b) Volenti non fit injuria
Ans: The legal maxim “Volenti non fit injuria” means “to one who consents, no harm is done.” It implies that a person who voluntarily consents to a risk cannot claim damages for injury resulting from it.

c) Fallacy of Accident and Converse Accident
Ans: The Fallacy of Accident arises when a general rule is wrongly applied to a particular case to which it does not fit. The Converse Accident occurs when a rule derived from an exceptional case is wrongly applied as a general principle.

d) Bob Brown’s Case
Ans: In Bob Brown’s Case, the fallacy of False Cause was demonstrated where one event was wrongly assumed to cause another merely because it preceded it. It highlights the error of confusing correlation with causation.

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Q.3 Answer the following (Any Two)

a) Test the validity of the following categorical syllogism and reduce it to its proper logical form:
“Beggars, who have no property, can receive no injustice because justice is nothing but violation of property.”
Ans:
Major Premise: All cases of justice are cases involving property.
Minor Premise: Beggars have no property.
Conclusion: Therefore, beggars can receive no injustice.
This syllogism is valid in the first figure following the AAA mood (Barbara).

b) The formal study of Logic is useless, for many persons who have never studied Logic can reason shrewdly and accurately.
Ans:
This argument commits the fallacy of False Analogy, as it assumes that natural ability to reason is the same as formal logical study. The conclusion does not logically follow from the premises.

c) Reduce the following and construct a strict categorical syllogism:
“None but the wise are good, and none but the good are happy, therefore, none but the wise are happy.”
Ans:
Major Premise: All good persons are wise.
Minor Premise: All happy persons are good.
Conclusion: Therefore, all happy persons are wise.
This is valid and follows the AAA mood in the first figure.

d) Learned men sometimes become mad, but as he is not learned, there is no danger to his sanity.
Ans:
This is an invalid syllogism as it commits the fallacy of denying the antecedent. The correct logical form should be tested through indirect reduction to BOCARDO form.

e) Identify the following and give reasons:

1. Every man desires his own happiness, therefore, all men desire universal happiness.
   Ans: Fallacy of Composition – what is true of individuals is wrongly assumed true of the whole group.
2. You had been leading an immoral life. How can you become a preacher?
   Ans: Argument ad hominem – attacking the person instead of addressing the argument.
3. Untouchability must be removed because Gandhi says so.
   Ans: Argument ad verecundiam – appeal to inappropriate authority.

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Q.4 Answer question no. 4(d) and any one from (a), (b), (c)

a) State and explain the rules of structure of categorical syllogism.
Ans:
Rules:
1) A syllogism must have only three terms – major, minor, and middle.
2) The middle term must be distributed at least once.
3) No term can be distributed in the conclusion if it is not distributed in the premises.
4) Two negative premises yield no conclusion.
5) If one premise is negative, the conclusion must be negative.
6) From two particular premises, no conclusion follows.
These rules ensure logical consistency and validity of categorical syllogisms.

b) What is Hypothesis? Elaborate on the characteristics of a hypothesis.
Ans:
A hypothesis is a tentative statement or assumption explaining certain facts. Characteristics include:
1) It must be clear and definite.
2) It should be testable and verifiable.
3) It must be consistent with established facts.
4) It should be capable of explaining all related phenomena.
5) It must be free from contradictions and be simple and economical.
Hypothesis plays a key role in scientific investigation.

c) Explain the significance of the scientific notion of cause in Law.
Ans:
In law, the scientific notion of cause ensures that liability or responsibility is fixed based on actual causal connection. It prevents arbitrary judgments by distinguishing between proximate and remote causes, ensuring justice based on rational cause-effect relations.

d) Construct complex constructive dilemma. Rebut and Refine it:
Ans:
Example:
If there is goodness in the heart, there will be peace.
If there is hatred in the heart, there will be lack of happiness.
Either there is goodness or there is hatred in the heart.
Therefore, either there will be peace or lack of happiness.
Rebuttal: Denying both consequents allows rejection of both antecedents. Refinement shows that both cannot be true together, establishing a rational alternative structure.