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BLS LLB 5 Years Sem 1 Logic 1 2024-25 - ATKT Set 2 60/40 Question Paper with Solutions

Mumbai University Solved Question Papers

Logic 1

Previous Year Question Paper with Solution

BLS LLB 5 Years · Sem 1

2024-25 - ATKT Set 2 60/40 Examination

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Mumbai

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First published on munotes.in on 10 August 2026.

Published by munotes.in, Mumbai.

Model answers written and edited by the munotes.in editorial desk.

Passages from this volume may be quoted, in print, online or by an AI system, with credit: name munotes.in and link to this volume's page. The volume may not be reproduced as a whole. Full terms at munotes.in/content-license.

munotes.in is an independent study resource for students of the University of Mumbai. It is not affiliated with the University of Mumbai, and is not endorsed by it.

The University does not publish an official answer key for this paper. The answers in this volume are model answers, written to show how a full-mark answer is built. They are a study aid, not an authority on what an examiner marked.

The question paper reproduced here is the paper as set by the University of Mumbai at the 2024-25 - ATKT Set 2 60/40 examination.

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The Paper as Set

The questions in this volume are the questions asked at the 2024-25 - ATKT Set 2 60/40 examination, reproduced as the University of Mumbai set them, in the order it set them. Nothing has been reworded, added or left out. Only the answers are ours. See the original question paper.

Duration 2 hours  ·  Total marks 60  ·  22 questions answered

How to use this volume

Solve the paper first, under exam conditions and against the clock. Then read the answers here and mark your own. Reading a solution before attempting the question feels productive and teaches very little, because recognising an answer is not the same as being able to write one.

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SECTION I

Q.1) Answer the following in one or two sentence

any 6 · (12 marks)

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1.Define logic.[2]

Answer

Logic is the science and the art of reasoning: the study of the methods and principles by which correct reasoning is distinguished from incorrect reasoning.

The word comes from the Greek logos, meaning word, thought or reason. The subject was founded by Aristotle, whose logical works are collected as the Organon, the instrument.

Two standard definitions:

  1. Whately: logic is the science, and also the art, of reasoning.
  2. Copi: logic is the study of the methods and principles used to distinguish correct from incorrect reasoning.
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2.What is meant by proposition? Give one example.[2]

Answer

A proposition is a statement in which something is affirmed or denied of something else, and which is therefore necessarily either true or false.

Example: "All men are mortal."

It has three parts: the subject ("men"), the predicate ("mortal") and the copula ("are"), which joins the two and asserts the relation between them.

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3.State the meaning of negative term.[2]

Answer

A negative term is a term which connotes the absence of a quality or attribute in the thing it denotes. It is usually formed by prefixing not, non, un, in or dis to the corresponding positive term.

Examples: not-man, non-Indian, dishonest, illegal, incompetent.

It stands opposed to a positive term, which connotes the presence of the quality: man, honest, legal. The two are contradictory, so between them they exhaust the universe of discourse and everything is either a man or a not-man.

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4.Define subjective connotation.[2]

Answer

Connotation is of three kinds, and the subjective connotation of a term is the set of attributes which a particular individual actually associates with that term in their own mind.

It varies from person to person and with each person's knowledge and experience. To a chemist the subjective connotation of "water" includes its molecular composition; to a child it is a clear liquid that quenches thirst.

The other two kinds are:

  1. Objective connotation: the whole set of attributes actually possessed by the things the term denotes, known and unknown alike.
  2. Conventional connotation: the attributes fixed by the usage of the language community, which is what a definition states and what logic works with.
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5.What is a definiendum?[2]

Answer

The definiendum is the term to be defined: the word whose meaning a definition sets out to fix.

The expression which does the defining is called the definiens.

Example: in "A contract is an agreement enforceable by law", the definiendum is "contract" and the definiens is "an agreement enforceable by law".

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6.State immediate inference.[2]

Answer

Immediate inference is an inference drawn from a single premise, without the help of a middle term: the conclusion follows directly from one proposition.

Its two branches are:

  1. Opposition, in which the subject and predicate stay unchanged and only the quantity or the quality differs: from "All advocates are graduates" being true it follows at once that "Some advocates are not graduates" is false.
  2. Eduction, in which the terms change place or are replaced by their contradictories: conversion, obversion, contraposition and inversion.
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7.Define primary induction.[2]

Answer

Primary induction is induction proper: the process by which a general proposition is established directly from the observation of particular instances, by observation and experiment, and on the strength of the law of universal causation and the uniformity of nature.

Example: from observing that this piece of iron expands when heated, and that one, and that one, we establish the general proposition that all metals expand when heated.

It is contrasted with secondary induction, in which no fresh observation is made and a new general truth is deduced from laws already established by primary induction, as when the law of falling bodies is derived from the law of gravitation.

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8.Define law of identity.[2]

Answer

The Law of Identity is the first of the three laws of thought. It states that whatever is, is: everything is identical with itself.

Symbolically: A is A, or p ⊃ p.

Its practical force is that a term must keep the same meaning throughout an argument. A word that shifts its sense between premise and conclusion breaks the law, and the resulting mistake is the fallacy of equivocation.

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9.What is conversion?[2]

Answer

Conversion is a form of eduction, that is, of immediate inference, in which the subject and the predicate of a proposition change places, the quality remaining the same and the meaning unchanged. The original is the convertend, the inferred proposition is the converse.

Its rule: no term may be distributed in the converse unless it was distributed in the convertend.

FormConvertendConverse
AAll S is PSome P is S (conversion by limitation)
ENo S is PNo P is S (simple conversion)
ISome S is PSome P is S (simple conversion)
OSome S is not Pno converse is possible
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10.What is relational Proposition?[2]

Answer

A relational proposition is one which asserts a relation between two or more terms, instead of attributing a predicate to a single subject.

Examples: "Shyam is taller than Ravi"; "Bombay is west of Nagpur"; "A owes money to B".

Traditional logic could not handle them, because it had to force every proposition into subject, copula and predicate. Modern logic symbolises them with a many-place predicate: "Shyam is taller than Ravi" is written Tsr, where T is the two-place relation "... is taller than ...", s is Shyam and r is Ravi.

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SECTION II

Q.2) Write Short Notes

any 2 · (12 marks)

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11.Singular and general term[6]

Answer

For full marks, cover: what a term is; each kind defined with examples; the third kind, collective; the table of differences; connotation and denotation applied to each; and the legal application.

What a term is

A term is a word or group of words which can stand as the subject or the predicate of a proposition. Terms are classified in several ways, and one of them is by how many individuals the term applies to.

Singular term

A singular term is one which denotes a single definite individual, and only that individual.

Its kinds:

  1. Proper names: Rama, the Ganga, the Taj Mahal.
  2. Descriptive phrases that pick out one individual: the present Chief Justice of India, the author of Hind Swaraj.
  3. Demonstratives with a common noun: this book, that man.
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General term

A general term is one which denotes each of an indefinite number of individuals, and connotes the attributes they share.

Examples: man, table, advocate, contract. "Man" applies to Rama, to Shyam and to every other human being, and it applies to each of them distributively, that is, one at a time.

The third kind: collective term

A collective term denotes a group taken as a whole, and does not apply to the members individually. Examples: army, jury, Parliament, library. A soldier is not an army, whereas a man is a man.

⚠️ The same word can be general or collective according to its use. "Jury" in "the jury returned a verdict" is collective; in "juries are drawn from the electoral roll" it is general, standing for each jury.

The differences

PointSingular termGeneral term
DenotesOne definite individualAn indefinite number of individuals
Applies to membersThere are noneDistributively, each one at a time
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PointSingular termGeneral term
ConnotationNone, on the traditional viewThe attributes common to all it denotes
Can be defined?Not per genus et differentiamYes, by genus and differentia
Used asThe subject of a singular propositionThe subject or predicate of a general proposition
In modern logicAn individual constant, a, b, cA predicate, Sx, Px

Why a singular term is said to have no connotation

A proper name identifies without describing. "Rama" tells you which individual is meant and nothing about what he is like, and it would go on naming the same person if every one of his attributes changed. J.S. Mill put it that a proper name is a mark set on an individual, not a description of him. It follows that a proper name cannot be defined per genus et differentiam, since it has no differentia within a species, and can only be explained by describing the individual.

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Legal application

The distinction runs through drafting. A statute that names an individual or a body is using a singular term and applies to that one alone; a statute that speaks of "an employee", "a consumer" or "an occupier" is using a general term and applies distributively to each. A collective term in a statute is the trap: a provision about "the Board" is not a provision about each member of the board, and reading a collective term distributively is the fallacy of division.

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12.Weak and strong disjuncts[6]

Answer

For full marks, cover: what a disjunctive proposition is and what a disjunct is; both senses with symbol, meaning and truth table; the test that tells them apart; why logic takes the weak sense as basic; the disjunctive syllogism and the fallacy it invites; and the legal application.

The disjunctive proposition

A disjunctive or alternative proposition asserts an alternation between two or more propositions, joined by "either ... or". Each component is called a disjunct or an alternative.

Example: "Either the accused confesses or the prosecution proves the charge."

The words "either ... or" carry two different meanings in ordinary English, and the two disjuncts are accordingly called weak or strong.

The weak, or inclusive, sense

A weak disjunction asserts that at least one of the disjuncts is true, and leaves open the possibility that both are.

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Symbol: p v q. False only when both disjuncts are false.

pqp v q
TTT
TFT
FTT
FFF

Example: "Candidates who are graduates or have three years of experience may apply." A graduate with three years of experience is not disqualified.

The strong, or exclusive, sense

A strong disjunction asserts that at least one disjunct is true and that not both are: one but not both.

Symbol: (p v q) · ~(p · q). True only when the disjuncts differ.

pqp v q~(p · q)strong disjunction
TTTFF
TFTTT
FTTTT
FFFTF
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Example: "The accused is either guilty or innocent." He cannot be both.

How to tell which is meant

Ask whether the two disjuncts can both hold. Where they are contradictories, or are otherwise mutually exclusive by their nature, the sense is strong. Where they can coexist, the sense is weak. English gives no reliable sign, which is why the symbol is fixed by definition.

Why logic takes the weak sense as basic

Because the weak sense is the weaker of the two and is common to both uses. Whatever the strong sense asserts, the weak sense asserts as well, with the extra denial ~(p · q) added. So logic takes the weaker as the primitive connective and builds the stronger out of it when it is wanted, rather than the other way round.

The disjunctive syllogism, and the fallacy it invites

From a disjunction and the denial of one disjunct, the other follows, and this holds in both senses:

Either p or q. Not p. Therefore q.

But arguing from the affirmation of one disjunct to the denial of the other,

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Either p or q. p. Therefore not q,

is valid only in the strong sense. In the weak sense it is a fallacy, because both may be true. That single asymmetry is the practical reason for keeping the two apart.

Legal application

A statute that penalises one who "sells or offers for sale" uses the weak sense: doing both is not a defence. A section giving a party a remedy "by suit or by arbitration" is usually strong, because electing one bars the other. Whether "or" is weak or strong in a given section is a question of construction, and courts sometimes read "or" as "and" where the context requires it.

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13.Disablement[6]

Answer

For full marks, cover: the statute; both definitions with their section numbers; the fourfold classification with the two bases it uses; the deeming provisions and the Schedule; how compensation follows; and, because this is a logic paper, what the classification illustrates about definition and division.

The statute

Disablement is defined by the Employee's Compensation Act 1923, formerly the Workmen's Compensation Act, which makes an employer liable to pay compensation for personal injury caused to an employee by accident arising out of and in the course of employment.

Disablement in this sense is the loss or reduction of earning capacity resulting from such an injury. Note that the Act measures it by earning capacity, not by physical injury as such: two people with the same wound may suffer different disablement.

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Partial disablement, Section 2(1)(g)

Where the disablement is of a temporary nature, such disablement as reduces the earning capacity of the employee in the employment in which he was engaged at the time of the accident.

Where it is of a permanent nature, such disablement as reduces his earning capacity in every employment which he was capable of undertaking at that time.

Every injury specified in Part II of Schedule I is deemed to result in permanent partial disablement.

Total disablement, Section 2(1)(l)

Such disablement, whether temporary or permanent, as incapacitates the employee for all work which he was capable of performing at the time of the accident.

It is deemed to result where the combination of injuries specified in Part I of Schedule I produces a loss of earning capacity of one hundred per cent or more.

The fourfold classification

The Act divides disablement on two bases at successive steps: first by extent, into partial and total, and then by duration, into temporary and permanent. Four kinds result.

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TemporaryPermanent
PartialEarning capacity reduced in the same employment, for a timeEarning capacity reduced in every employment he could then undertake
TotalIncapacitated for all such work, for a timeIncapacitated for all such work, for life

Why the definitions are drawn as they are

The difference between the two limbs of Section 2(1)(g) is deliberate and is where the cases are fought. Temporary partial disablement is measured against the employment he was in; permanent partial disablement is measured against every employment he could then have undertaken. A clerk who loses a finger may be unable to do his own job for a month and yet remain able to do it permanently, so the two limbs give different answers on the same facts.

Compensation

Section 4 fixes the amount, and it follows the classification: death and permanent total disablement are compensated by a percentage of monthly wages multiplied by a relevant factor, permanent partial disablement by the percentage of loss of earning capacity given in Schedule I, and temporary disablement by a half-monthly payment.

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14.Division and definition[6]

Answer

For full marks, cover: each operation defined with its elements; the connotation and denotation link that explains why they are a pair; the rules of each, briefly; the table of comparison; where each fails; and a legal application.

The pair, and why they belong together

Every general term has a connotation, the attributes it implies, and a denotation, the individuals or classes it applies to.

Definition sets out the connotation of a term. Division sets out the denotation. That is the whole relation between them, and it is why no syllabus treats one without the other.

Definition

A definition is a statement which sets out the connotation of a term, that is, the attributes a thing must possess before the term applies to it. The term is the definiendum, the defining expression the definiens.

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Its classical form is per genus et differentiam: state the proximate genus and the differentia. "Man is a rational animal": animal is the genus, rational the differentia.

Its rules, in brief: state the essential attributes; be co-extensive, neither too wide nor too narrow; do not be circular; do not use obscure or figurative language; do not be negative where an affirmative is possible.

Division

Division is the process of separating a class into the sub-classes or species contained under it, on the basis of a single attribute.

Its three elements are the totum divisum, the class divided; the membra dividentia, the dividing members; and the fundamentum divisionis, the single attribute on which the division rests.

Its rules, in brief: use only one fundamentum divisionis at each step; the members must be mutually exclusive; the division must be exhaustive; it must proceed step by step; and every member must be a species of the genus divided.

The comparison

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PointDefinitionDivision
Deals withConnotationDenotation
OperationMarks a class off from othersBreaks a class into its species
DirectionLooks upward, to the genus aboveLooks downward, to the species below
ProductA statementA list of species
Governing elementThe differentiaThe fundamentum divisionis
Chief fallaciesToo wide, too narrow, circular, obscureCross-division, overlapping, incomplete, leap, partition
LimitsCannot define the summum genus, individuals or simple qualitiesCannot divide an individual, or an infima species

Where each stops

Definition fails at three points: the summum genus (being, substance) has no wider class to serve as genus; an individual has no differentia within a species, so a proper name cannot be defined; and a simple unanalysable quality (red, sweet) has no parts to take apart.

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Division fails at two: an individual cannot be divided into kinds, only partitioned into parts; and an infima species, the lowest species, has no species under it to divide into.

They are two halves of one operation

Each depends on the other. To define a term you must name its genus, which is to place it in a division already made. To divide a class you must know which attribute is essential, which is what a definition states. The two are performed together, and the tree of Porphyry, running from substance down to man, is a division at every step and a definition at every node.

Legal application

The definition clause of a statute is a definition; the Schedule or the list of categories is a division. Section 2(h) of the Indian Contract Act 1872 defines a contract as an agreement enforceable by law, which is genus plus differentia. The division of nuisance into public and private is a division on a single basis, and it satisfies every rule. Where a taxing schedule mixes bases, its entries overlap and an assessee falls under two at once, which is why cross-division is a drafting fault before it is a logical one.

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SECTION III

Q.3) Solve any two questions

12 marks

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15.a) Reduce the following sentences into logical form and identify and name distributed term or terms, giving reasons.[6]

  • (i) Every student in the school is present today.
  • (ii) Lawyers are sometimes doctors.
  • (iii) Rarely drums are buckets.

Answer

Strict logical form and the distribution rule

A proposition is in strict logical form when it reads

quantity sign + subject term + copula (is or are, present tense) + predicate term

FormPropositionSubjectPredicate
AAll S is Pdistributedundistributed
ENo S is Pdistributeddistributed
ISome S is Pundistributedundistributed
OSome S is not Pundistributeddistributed

Universals distribute the subject; negatives distribute the predicate.

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(i) Every student in the school is present today.

All students in the school are persons present today. (A proposition)

Distributed: the subject, "students in the school", only.

Reason: "Every" is a universal sign, so the whole of the subject is spoken of and the subject is distributed. The proposition is affirmative, so the predicate is undistributed: it says nothing about every person who is present today, only that the students are among them. The words "in the school" belong to the subject term and must be kept with it, and "today" is carried into the predicate term, because the copula must be the bare present tense.

(ii) Lawyers are sometimes doctors.

Some lawyers are doctors. (I proposition)

Distributed: neither term.

Reason: "sometimes" is a word of time doing the work of a particular quantity sign, exactly as "always" does the work of a universal one. The proposition speaks of a part of the subject only, and it is affirmative, so neither term is distributed.

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(iii) Rarely drums are buckets.

Some drums are not buckets. (O proposition)

Distributed: the predicate, "buckets", only.

Reason: "rarely" belongs with "seldom" and "few": it means not often, and the negative force is part of its meaning. A proposition of the form "Rarely S are P" therefore asserts that most S are not P, which is a particular negative. Being negative, it distributes its predicate; being particular, it leaves its subject undistributed.

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16.b) i) Construct a truth table for the following compound proposition: "If you study hard then you will achieve success."[6]

  • (ii) Identify and symbolise the following simple propositions.
  • (1) Sachin Tendulkar is a great cricketer.
  • (2) Shyam is taller than Ravi.
  • (3) Taj Mahal is beautiful.

Answer

(i) "If you study hard then you will achieve success"

Identification: a compound proposition; the connective is the conditional, or implication, signalled by "if ... then".

  • Let p = You study hard.
  • Let q = You will achieve success.

Symbolic form: p ⊃ q

p is the antecedent and q the consequent.

Truth table

pqp ⊃ q
TTT
TFF
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pqp ⊃ q
FTT
FFT

Reading of the table: the conditional is false in one case only, where the antecedent is true and the consequent false. The promise is broken only by someone who studies hard and does not achieve success. It is contingent, neither a tautology nor a contradiction.

(ii) Identify and symbolise the following simple propositions

1. Sachin Tendulkar is a great cricketer.

A singular proposition, that is, a class-membership proposition: a predicate is attributed to a named individual, so no quantifier is used.

Gs, where G = "... is a great cricketer" and s = Sachin Tendulkar.

2. Shyam is taller than Ravi.

A relational proposition: it does not attribute a quality to a subject but asserts a relation between two individuals.

Tsr, where T = "... is taller than ...", s = Shyam and r = Ravi.

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The order matters: Tsr and Trs say opposite things. Note also that the relation "taller than" is asymmetrical and transitive.

3. Taj Mahal is beautiful.

A singular proposition, again class-membership: a predicate attributed to a named individual.

Bt, where B = "... is beautiful" and t = the Taj Mahal.

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17.c) Identify the following modern definitions and provide reasons for your analysis.[6]

  • (i) Furniture means table, chair, cupboard etc.
  • (ii) "Sayonara means 'goodbye' in Japanese."
  • (iii) "What you see in the water now is an aquatic animal."

Answer

The kinds of definition to choose from

Denotative or extensional techniques: by example, by enumeration, ostensive. Connotative or intensional techniques: synonymous (biverbal), operational, genus and difference. By purpose: stipulative, lexical, precising, theoretical, persuasive.

(i) Furniture means table, chair, cupboard etc.

Kind: an extensive definition, that is, a definition by enumeration. A denotative technique.

Reasons: the term is defined by listing the species it denotes rather than by stating the attributes it connotes. The word "etc." is the definition's own admission that the list is incomplete, which is the standing weakness of the extensive form wherever the class is open: beds, desks, almirahs and sofas are furniture too.

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It also says nothing about why those things belong together, so a reader who met a new article of furniture could not tell from this definition whether it was one. A real definition names the genus and the differentia: furniture is movable articles used to make a room fit for living or working in.

(ii) "Sayonara means 'goodbye' in Japanese."

Kind: a biverbal, or synonymous, definition. A connotative technique, and a nominal definition rather than a real one.

Reasons: one word is given by another word of the same meaning, here in another language. No fallacy arises, because a biverbal definition is a legitimate technique doing exactly what it exists to do: it tells a reader who knows English what a Japanese word stands for.

Its limit should still be named. It helps only a reader who already knows the synonym, and it analyses nothing, so it could not tell anyone what a farewell is. It is a definition of a word, not of a thing.

(iii) "What you see in the water now is an aquatic animal."

Kind: an ostensive, or demonstrative, definition. A denotative technique.

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Reasons: the meaning is conveyed by pointing at an instance. The words "what you see in the water now" do no defining at all; they only direct attention to a specimen.

Its limits are the ones the sentence itself shows. It depends entirely on the situation, so it fails the moment the water is empty or holds something else, and the words "now" make it useless a minute later. It also cannot show which feature the term picks out: a listener shown a fish might take "aquatic animal" to mean anything with fins, anything silver, or that particular fish.

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18.d) Evaluate the following divisions. Give Reasons.[6]

  • (i) Animals classified into domestic and wild.
  • (ii) Books into fiction, non-fiction.
  • (iii) Music into classical, rock, pop, and jazz.

Answer

The rules of logical division

  1. Only one fundamentum divisionis at each step; breach is cross-division.
  2. The members must be mutually exclusive.
  3. The division must be exhaustive.
  4. It must proceed step by step; breach is the saltus in dividendo.
  5. Every member must be a species of the genus divided.

Two of the three below are sound, and showing that is as much a part of the answer as finding a fault.

(i) Animals classified into domestic and wild.

Sound. This is a division on a single basis, and a dichotomy in substance.

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Reasons: one fundamentum divisionis is used, the relation of the animal to man, that is, whether it has been tamed and kept. "Wild" here does the work of "not domestic", so the two members are contradictories and the division is necessarily exhaustive and mutually exclusive. Every rule is satisfied.

The qualification worth adding: a feral animal, once domesticated and now living wild, sits awkwardly, and so does a captive wild animal. That does not break the division, because the members remain exclusive in the same respect and at the same time; it means only that the attribute is one an animal can acquire and lose.

(ii) Books into fiction, non-fiction.

Sound. This is a division by dichotomy and it is formally faultless.

Reasons: one fundamentum divisionis is used, whether the content is invented or not. The two members are contradictories, so the division is necessarily exhaustive, since every book must be one or the other, and mutually exclusive, since no book can be both.

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The criticism that may fairly be made is of usefulness, not validity. "Non-fiction" is a negative member and is wholly indeterminate: it lumps history, biography, science, law and cookery into one remainder and tells us nothing about any of them. Dichotomy is therefore a first step, and at the next step the negative member must be broken into positive species.

(iii) Music into classical, rock, pop, and jazz.

Faulty: the division is incomplete, and the members are not clearly exclusive.

Reasons: it is incomplete, because folk music, devotional music, film music, blues and electronic music are all music and none of them is named, so the members taken together fall well short of the genus. Rule 3 is broken.

The members are also not mutually exclusive in practice, because the boundaries of a genre are not sharp and a great deal of music is jazz-rock or classical-pop at once. Rule 2 is therefore satisfied only loosely, and the reason is that the fundamentum divisionis, musical genre, is itself a matter of degree rather than of a single definite attribute. A division is only as sharp as its basis.

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SECTION IV

Q.4) Answer the following questions in details. Q.4

d · is compulsory. Attempt any one question from 4(a), (b) and (c) (24 marks)

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19.a) Discuss the importance of logic in everyday life.[12]

Answer

For full marks, cover: a short definition to open with; the general case for logic in ordinary affairs; then the uses under numbered heads, each with an everyday illustration; the fallacies met in daily life, named; the objection that people reason well without studying logic, and the answer to it; the limits; and a conclusion.

Definition, briefly

Logic is the science and the art of reasoning, the study of the methods and principles by which correct reasoning is distinguished from incorrect. It is a normative science: it states how we ought to reason, not how we do.

That distinction is the whole ground of this question. Everyone reasons; not everyone reasons well; and logic is the standard against which the difference is measured.

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The uses of logic in everyday life

1. It makes our own thinking consistent. The three laws of thought are the minimum conditions of coherent belief. A person who holds two contradictory opinions at once, or who uses a word in one sense in a premise and another in a conclusion, cannot be argued with and cannot decide anything. Logic supplies the discipline of holding one meaning at a time.

2. It teaches us to define our terms. Most everyday disputes are verbal, not real: the parties agree on the facts and use a word differently. A quarrel about whether a film is "art" or whether a colleague was "rude" ends the moment the word is defined, and logic supplies the rules for defining it neither too widely nor too narrowly.

3. It sharpens our reading of what other people assert. Everyday speech hides the quantity of a proposition. "Politicians are corrupt", "Young people don't read", "This medicine never fails" are universal claims made without evidence, and reducing a sentence to strict logical form exposes how much is being claimed. A single counter-instance answers a universal, and knowing that is a practical skill.

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4. It protects against advertising and propaganda. An advertisement that says a product is "used by nine out of ten experts" is an induction from an unstated sample; one that says a rival is "for people who don't care about their family" is a persuasive definition. Both work only on a reader who does not name what is being done.

5. It is the basis of ordinary decision-making. Weighing alternatives is disjunctive reasoning; working out consequences is hypothetical reasoning; eliminating possibilities is a disjunctive syllogism. A person deciding which route to take is running an argument, whether or not it is written down.

6. It underlies every piece of practical induction. Believing that the bus is usually late, that a shop is honest, or that a medicine works is induction by simple enumeration, and knowing its weakness, that one contrary instance destroys it and that a run of agreeing cases may be coincidence, is a corrective people badly need.

7. It improves expression. An argument set out with its premises and conclusion separated is easier to state and easier to answer, which is as useful in a family conversation as in a court.

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8. It is the ground of the sciences and of law, both of which everyone meets as a citizen: reading a news report of a study, or a notice from an authority, is easier for someone who can see the argument inside it.

The fallacies of everyday life

Naming them is half of resisting them, and each is met daily:

  1. Argumentum ad hominem: attacking the person instead of the argument.
  2. Ad populum: this is what everybody thinks, so it is true.
  3. Ad verecundiam: an appeal to an authority outside their field, which is what a celebrity endorsement is.
  4. Ad misericordiam: an appeal to pity in place of a reason.
  5. Petitio principii: assuming in the premise what the conclusion has to prove.
  6. Hasty generalisation: one bad experience of a place or a group taken as a rule.
  7. False cause, post hoc ergo propter hoc: the recovery followed the remedy, so the remedy caused it.
  8. False analogy: running a country is just like running a household.
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The objection, and the answer

It is often said that logic is useless in ordinary life, because people reasoned correctly for thousands of years before Aristotle wrote a word, and because nobody sets out a syllogism before crossing a road.

The answer is the one given for grammar. People spoke before grammar was written, and grammar still improves and corrects their speech. Logic does not create the capacity to reason; it makes an unconscious capacity conscious, supplies a standard for judging a doubtful case, and gives a vocabulary in which a mistake can be pointed out. The person who cannot say what is wrong with an argument is at the mercy of anyone who argues confidently.

The limits

Logic tests the form of reasoning; it does not supply the premises, and it cannot tell anyone what to want. A perfectly valid argument from false or heartless premises is still valid. It is also not a substitute for knowledge: the reasoning of a doctor is only as good as the medicine behind it. Logic is necessary and not sufficient for good thinking.

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Conclusion

Logic matters in everyday life because ordinary life is full of arguments, most of them unexamined. It makes belief consistent, disputes soluble, claims measurable and fallacies nameable. It does not make anyone wise, and it does not decide what is worth pursuing; it ensures only that the way from what a person accepts to what they conclude is sound, which is the smallest thing that can honestly be asked of any piece of thinking.

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20.b) Illustrate the fourfold classification of proposition.[12]

Answer

For full marks, cover: what the fourfold classification is and the two bases it rests on; quantity with its signs; quality with the rule about the copula; the four forms in a table with worked examples, since the question says "illustrate"; the letters and their origin; distribution; the awkward propositions and how they are forced into the four forms; the uses of the classification; and the modern re-expression.

What the fourfold classification is

The fourfold classification divides categorical propositions into A, E, I and O, by combining the two divisions of quantity with the two divisions of quality. It is the foundation of traditional deductive logic, because opposition, eduction and the syllogism are all stated in terms of these four.

Quantity

Settled by how much of the subject is spoken of.

  1. Universal: the predicate is affirmed or denied of the whole of the subject. Signs: all, every, any, no, none, whoever, always, never.
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  1. Particular: the predicate is affirmed or denied of a part. Signs: some, a few, many, most, certain, sometimes.

Quality

Settled by whether the copula joins or separates.

  1. Affirmative: the predicate is affirmed of the subject.
  2. Negative: the predicate is denied of the subject.

⚠️ The quality is carried by the copula and nothing else. "All men are not-honest" is affirmative with a negative predicate; "All men are not honest" is a different proposition.

The four forms, illustrated

FormQuantityQualityTypeExampleLegal example
AUniversalAffirmativeAll S is PAll men are mortalAll agreements with a minor are void
EUniversalNegativeNo S is PNo men are angelsNo minor is competent to contract
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FormQuantityQualityTypeExampleLegal example
IParticularAffirmativeSome S is PSome men are honestSome agreements are enforceable
OParticularNegativeSome S is not PSome men are not honestSome agreements are not enforceable

The letters come from the Latin AffIrmo, I affirm, and nEgO, I deny: the first two vowels of each word give the two affirmative and the two negative forms.

What follows: distribution

A term is distributed when the proposition speaks of every member of the class it names.

FormSubjectPredicate
Adistributedundistributed
Edistributeddistributed
Iundistributedundistributed
Oundistributeddistributed

Universals distribute the subject; negatives distribute the predicate. Quantity governs the subject, quality governs the predicate.

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The propositions that do not fit, and how they are forced in

Since the question says "illustrate", these matter, because they are what a reduction question actually puts in front of a student.

  1. Singular: "Socrates is wise." No quantity in the ordinary sense; traditional logic treats it as universal, so that it can be used in a syllogism.
  2. Indefinite: "Dogs are faithful." No quantity sign printed; read as universal when it states a general truth, particular when it reports a fact about some.
  3. Exclusive: "Only citizens may vote." Becomes an A proposition with the terms interchanged: "All voters are citizens".
  4. Exceptive: "All but minors are competent." Becomes two propositions: "All non-minors are competent" and "No minors are competent".
  5. Propositions with a hidden verb: "Birds fly" becomes "All birds are creatures that fly", because the copula must be the bare verb "to be".
  6. Words of time as quantity signs: always and never are universal; sometimes is particular; rarely and seldom are particular and negative.

The uses of the classification

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  1. Opposition. The square is built on it: contraries differ in quality, subalterns in quantity, contradictories in both.
  2. Eduction. Conversion and obversion are stated form by form, and the rules follow from distribution: A cannot be converted simply, O cannot be converted at all.
  3. The syllogism. Its rules are rules about distribution: the middle term must be distributed at least once, and no term distributed in the conclusion may be undistributed in its premise.

The modern re-expression

Modern logic keeps the four and rewrites them with quantifiers: (x)(Sx ⊃ Px), (x)(Sx ⊃ ~Px), (∃x)(Sx · Px), (∃x)(Sx · ~Px). The change is not cosmetic: on the modern reading a universal asserts nothing to exist, so A no longer implies I and E no longer implies O, and subalternation, contrariety and sub-contrariety all fail.

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Conclusion

The fourfold classification is quantity and quality taken together, and it is the smallest scheme that will carry the traditional machinery of inference. Two questions, each with two answers, give four forms; the four forms give the distribution table; and the distribution table gives most of the rules of traditional logic.

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21.c) Describe modern classification of proposition.[12]

Answer

For full marks, cover: why the traditional scheme was replaced; simple against compound; the connectives with one combined truth table; compounds that are not truth-functional; singular, relational and general propositions, with class membership against class inclusion; tautologous, contradictory and contingent forms; and a legal illustration.

Why a new classification was needed

Traditional logic classified propositions by quantity, quality, relation and modality, reducing everything to A, E, I and O. Three limits made that insufficient: it forces every proposition into the subject-predicate mould; it cannot express relations such as "Shyam is taller than Ravi"; and it cannot express multiple generality such as "every advocate has a client". It also offered no mechanical test of validity.

Modern logic, developed by Boole, Frege, Peano, Russell and Whitehead, classifies propositions by what determines their truth value.

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Simple and compound

A simple proposition contains no other proposition as a component. Example: "Rama is honest."

A compound proposition contains at least one other proposition as a component, joined by a connective. Example: "Rama is honest and Shyam is diligent."

A compound is truth-functional when its truth value is completely determined by the truth values of its components and the connective. That property is what makes the truth table possible, and it is the heart of the classification.

The connectives

1. Negation (~p), "not p". Reverses the truth value.

p~p
TF
FT

2. Conjunction (p · q), "p and q". The components are conjuncts. True only when both are true.

3. Disjunction (p v q), "p or q". The components are disjuncts. Inclusive: false only when both are false. The exclusive sense is (p v q) · ~(p · q).

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4. Implication (p ⊃ q), "if p then q". Antecedent and consequent. False only when the antecedent is true and the consequent false. This is material implication, and asserts no real connection.

5. Equivalence (p ≡ q), "p if and only if q". True when both components have the same truth value.

The four binary connectives set out together, because the whole propositional calculus is in these four columns:

pqp · qp v qp ⊃ qp ≡ q
TTTTTT
TFFTFF
FTFTTF
FFFFTT

Compounds that are not truth-functional

A compound whose truth value is not settled by its components falls outside the scheme: "Rama believes that the earth is flat", "It is necessary that two and two are four", "He died because he was poisoned". Belief, modality and causation are handled by separate branches for exactly that reason.

Among the simple propositions

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  1. Singular, attributing a predicate to a named individual, needing no quantifier: "Sachin is a great cricketer", Gs. A class-membership proposition.
  2. Relational, asserting a relation between individuals: "Shyam is taller than Ravi", Tsr. The order matters, and traditional logic could not express this at all.
  3. General, formed by quantifying a propositional function: universal, (x)(Sx ⊃ Px), or existential, (∃x)(Sx · Px). A universal affirmative is a class-inclusion proposition.

The four traditional forms reappear as (x)(Sx ⊃ Px), (x)(Sx ⊃ ~Px), (∃x)(Sx · Px) and (∃x)(Sx · ~Px).

Statement forms by their truth tables

  1. Tautologous, true on every row: p v ~p.
  2. Contradictory, false on every row: p · ~p.
  3. Contingent, true on some rows and false on others: p ⊃ q.
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Legal illustration

Statutes are written in these connectives and the choice decides cases. Conjunction makes conditions cumulative: Section 10 of the Contract Act requires free consent and competence and lawful consideration and lawful object. Disjunction makes them alternative. Implication is the form of every proviso and deeming clause. Equivalence is what a definition clause asserts.

Conclusion

The modern classification groups propositions by what settles their truth value: simple or compound, and among the simple, singular, relational or general. It gains a mechanical test of validity, a symbolism free of the ambiguities of English, and the power to express relations and multiple generality. It does not discard the four traditional forms; it re-expresses them and shows what they always meant.

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22.d) Do as Directed.[12]

  • (i) Some solids are not crystals. (Give Contrary and contradictory)
  • (ii) Every diamond is a hard jewel. (Give Subaltern and contradictory)
  • (iii) No coaches are lenient. (Give contradictory and subaltern)
  • (iv) Some ambitious men are successful. (Give obverse and converse)
  • (v) All philosophers are lovers of wisdom. (Give converse and obverse)
  • (vi) Some scientists are not atheists. (Give obverse and converse)

Answer

For full marks, cover: each item with the given proposition reduced and its form named, both answers written out, and the rule that produces each; and the two items where what is asked cannot be given, answered with the reason.

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The tables the answers depend on

Opposition: contradictories are A with O and E with I; contraries are A with E; sub-contraries are I with O; subalterns are A with I and E with O. Only universals have contraries; only particulars have sub-contraries.

Conversion, subject to the rule that no term may be distributed in the converse unless it was distributed in the convertend:

FormConvertendConverse
AAll S is PSome P is S (by limitation)
ENo S is PNo P is S (simple)
ISome S is PSome P is S (simple)
OSome S is not Pnone possible

Obversion, which changes the quality and replaces the predicate by its contradictory, works for every form: A gives E, E gives A, I gives O, O gives I.

(i) Some solids are not crystals. (Give Contrary and contradictory) (2 marks)

An O proposition.

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  • Contrary: an O proposition has no contrary. Contrariety holds only between two universal propositions, A and E, which is why they occupy the top of the square. What an O proposition has at the foot of the square is a sub-contrary, the I proposition "Some solids are crystals".
  • Contradictory (A): All solids are crystals.

Write both: give the contradictory, name the sub-contrary, and say why there is no contrary. That is what the item is testing.

(ii) Every diamond is a hard jewel. (Give Subaltern and contradictory) (2 marks)

An A proposition: "All diamonds are hard jewels."

  • Subaltern (I): Some diamonds are hard jewels. Truth descends from the universal to the particular.
  • Contradictory (O): Some diamonds are not hard jewels.

(iii) No coaches are lenient. (Give contradictory and subaltern) (2 marks)

An E proposition.

  • Contradictory (I): Some coaches are lenient.
  • Subaltern (O): Some coaches are not lenient.
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(iv) Some ambitious men are successful. (Give obverse and converse) (2 marks)

An I proposition.

  • Obverse (O): Some ambitious men are not non-successful.
  • Converse (I): Some successful persons are ambitious men. An I proposition converts simply, because it distributes neither term and so nothing can go wrong.

(v) All philosophers are lovers of wisdom. (Give converse and obverse) (2 marks)

An A proposition.

  • Converse (I): Some lovers of wisdom are philosophers. This is conversion by limitation: the subject of an A proposition is distributed, but once it becomes the predicate of an affirmative proposition it may not be, so the converse must be weakened from "all" to "some".
  • Obverse (E): No philosophers are non-lovers of wisdom.

(vi) Some scientists are not atheists. (Give obverse and converse) (2 marks)

An O proposition.

  • Obverse (I): Some scientists are non-atheists.
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  • Converse: an O proposition cannot be converted. It has no converse.

Reason: the attempted converse would be "Some atheists are not scientists". In the original, "scientists" is the subject of a particular proposition and is undistributed; in the attempted converse it has become the predicate of a negative proposition and is therefore distributed. A term distributed in the converse but undistributed in the convertend breaks the rule of conversion, so the inference is invalid.

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Notes on These Answers

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Colophon

This volume prints the 2024-25 - ATKT Set 2 60/40 Logic 1 paper set by the University of Mumbai for BLS LLB 5 Years Sem 1, with a model answer to each of its 22 questions.

Written and edited by the munotes.in editorial desk. Published by munotes.in, Mumbai.

10 August 2026.

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