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
munotes.in
Mumbai
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
munotes.in
Mumbai
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.
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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.
The questions below are the paper as the University of Mumbai set it at the 2024-25 - ATKT Set 2 60/40 examination, in the order it was set.
MarksPage
MarksPage
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.
Q.1) Answer the following in one or two sentence
any 6 · (12 marks)
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:
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.
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.
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:
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".
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:
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.
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.
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.
| Form | Convertend | Converse |
|---|---|---|
| A | All S is P | Some P is S (conversion by limitation) |
| E | No S is P | No P is S (simple conversion) |
| I | Some S is P | Some P is S (simple conversion) |
| O | Some S is not P | no converse is possible |
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.
Q.2) Write Short Notes
any 2 · (12 marks)
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.
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.
A singular term is one which denotes a single definite individual, and only that individual.
Its kinds:
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.
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.
| Point | Singular term | General term |
|---|---|---|
| Denotes | One definite individual | An indefinite number of individuals |
| Applies to members | There are none | Distributively, each one at a time |
| Point | Singular term | General term |
|---|---|---|
| Connotation | None, on the traditional view | The attributes common to all it denotes |
| Can be defined? | Not per genus et differentiam | Yes, by genus and differentia |
| Used as | The subject of a singular proposition | The subject or predicate of a general proposition |
| In modern logic | An individual constant, a, b, c | A predicate, Sx, Px |
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.
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.
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.
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.
A weak disjunction asserts that at least one of the disjuncts is true, and leaves open the possibility that both are.
Symbol: p v q. False only when both disjuncts are false.
| p | q | p v q |
|---|---|---|
| T | T | T |
| T | F | T |
| F | T | T |
| F | F | F |
Example: "Candidates who are graduates or have three years of experience may apply." A graduate with three years of experience is not disqualified.
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.
| p | q | p v q | ~(p · q) | strong disjunction |
|---|---|---|---|---|
| T | T | T | F | F |
| T | F | T | T | T |
| F | T | T | T | T |
| F | F | F | T | F |
Example: "The accused is either guilty or innocent." He cannot be both.
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.
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.
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,
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.
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.
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.
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.
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.
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 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.
| Temporary | Permanent | |
|---|---|---|
| Partial | Earning capacity reduced in the same employment, for a time | Earning capacity reduced in every employment he could then undertake |
| Total | Incapacitated for all such work, for a time | Incapacitated for all such work, for life |
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.
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.
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.
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.
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.
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 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.
| Point | Definition | Division |
|---|---|---|
| Deals with | Connotation | Denotation |
| Operation | Marks a class off from others | Breaks a class into its species |
| Direction | Looks upward, to the genus above | Looks downward, to the species below |
| Product | A statement | A list of species |
| Governing element | The differentia | The fundamentum divisionis |
| Chief fallacies | Too wide, too narrow, circular, obscure | Cross-division, overlapping, incomplete, leap, partition |
| Limits | Cannot define the summum genus, individuals or simple qualities | Cannot divide an individual, or an infima species |
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.
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.
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.
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.
Q.3) Solve any two questions
12 marks
Answer
A proposition is in strict logical form when it reads
quantity sign + subject term + copula (is or are, present tense) + predicate term
| Form | Proposition | Subject | Predicate |
|---|---|---|---|
| A | All S is P | distributed | undistributed |
| E | No S is P | distributed | distributed |
| I | Some S is P | undistributed | undistributed |
| O | Some S is not P | undistributed | distributed |
Universals distribute the subject; negatives distribute the predicate.
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.
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.
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.
Answer
Identification: a compound proposition; the connective is the conditional, or implication, signalled by "if ... then".
Symbolic form: p ⊃ q
p is the antecedent and q the consequent.
Truth table
| p | q | p ⊃ q |
|---|---|---|
| T | T | T |
| T | F | F |
| p | q | p ⊃ q |
|---|---|---|
| F | T | T |
| F | F | T |
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.
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.
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.
Answer
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.
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.
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.
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.
Kind: an ostensive, or demonstrative, definition. A denotative technique.
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.
Answer
Two of the three below are sound, and showing that is as much a part of the answer as finding a fault.
Sound. This is a division on a single basis, and a dichotomy in substance.
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.
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.
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.
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.
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)
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.
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.
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.
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.
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.
Naming them is half of resisting them, and each is met daily:
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.
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.
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.
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.
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.
Settled by how much of the subject is spoken of.
Settled by whether the copula joins or separates.
⚠️ 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.
| Form | Quantity | Quality | Type | Example | Legal example |
|---|---|---|---|---|---|
| A | Universal | Affirmative | All S is P | All men are mortal | All agreements with a minor are void |
| E | Universal | Negative | No S is P | No men are angels | No minor is competent to contract |
| Form | Quantity | Quality | Type | Example | Legal example |
|---|---|---|---|---|---|
| I | Particular | Affirmative | Some S is P | Some men are honest | Some agreements are enforceable |
| O | Particular | Negative | Some S is not P | Some men are not honest | Some 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.
A term is distributed when the proposition speaks of every member of the class it names.
| Form | Subject | Predicate |
|---|---|---|
| A | distributed | undistributed |
| E | distributed | distributed |
| I | undistributed | undistributed |
| O | undistributed | distributed |
Universals distribute the subject; negatives distribute the predicate. Quantity governs the subject, quality governs the predicate.
Since the question says "illustrate", these matter, because they are what a reduction question actually puts in front of a student.
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.
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.
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.
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.
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.
1. Negation (~p), "not p". Reverses the truth value.
| p | ~p |
|---|---|
| T | F |
| F | T |
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).
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:
| p | q | p · q | p v q | p ⊃ q | p ≡ q |
|---|---|---|---|---|---|
| T | T | T | T | T | T |
| T | F | F | T | F | F |
| F | T | F | T | T | F |
| F | F | F | F | T | T |
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.
The four traditional forms reappear as (x)(Sx ⊃ Px), (x)(Sx ⊃ ~Px), (∃x)(Sx · Px) and (∃x)(Sx · ~Px).
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.
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.
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.
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:
| Form | Convertend | Converse |
|---|---|---|
| A | All S is P | Some P is S (by limitation) |
| E | No S is P | No P is S (simple) |
| I | Some S is P | Some P is S (simple) |
| O | Some S is not P | none 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.
An O proposition.
Write both: give the contradictory, name the sub-contrary, and say why there is no contrary. That is what the item is testing.
An A proposition: "All diamonds are hard jewels."
An E proposition.
An I proposition.
An A proposition.
An O proposition.
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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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.
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10 August 2026.
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