Question 1

Statements: • All children are students. • All students are players. Conclusions: I. All cricketers are students. II. All children are players. Choose the option that logically follows from the statements.

Accepted Answer

Introduction / Context: Questions of this form test classic categorical syllogism reasoning using inclusion (subset) chains. We are given two universal affirmative statements and asked which conclusion must hold in every model built from those premises. Given Data / Assumptions: Premise 1: All children are students (Children ⊆ Students). Premise 2: All students are players (Students ⊆ Players). Standard syllogism rules apply; terms refer to non-empty sets unless emptiness is explicitly relevant. No unstated relationships are assumed beyond the premises. Concept / Approach: For universal statements of the form “All A are B”, we can chain subsets: if A ⊆ B and B ⊆ C, then A ⊆ C. Conclusions must be entailed solely by this logic, not by common knowledge about sports or everyday meaning. Step-by-Step Solution: 1) Chain the premises: Children ⊆ Students and Students ⊆ Players.2) By transitivity, Children ⊆ Players. So every child is necessarily a player.3) Examine Conclusion I: “All cricketers are students.” The premises mention Students and Players, not Cricketers. Cricketers could be a subset of Players, a disjoint set, or overlap in many ways. There is no necessary containment Cricketers ⊆ Students.4) Examine Conclusion II: “All children are players.” This is exactly the transitive result from Step 2, so it must follow. Verification / Alternative check: Construct a countermodel for Conclusion I: Let Students = {s1}, Players = {s1, p2}, Children = {s1}. Let Cricketers = {p2}. All premises hold, but not all cricketers are students, refuting Conclusion I. Why Other Options Are Wrong: Only I: false, as shown by countermodel. Both I and II: false because I fails. Neither: false because II is true. “Data inadequate”: not applicable; the logic is determinate. Common Pitfalls: A common mistake is to treat “Players” as synonymous with “Cricketers.” The test uses abstract set relations; domain knowledge must not be injected. Another error is assuming reversals like Students ⊆ Children; universal statements do not imply converses. Final Answer: Only conclusion II follows.

Question 2

Statements: a) All metals are silver. b) All silver are diamond. c) Some diamonds are gold. d) Some gold are marbles. Conclusions: I. Some gold are metals. II. All metals are diamond. III. Some silver are marble. IV. Some gold are silver. Select the…

Accepted Answer

Introduction / Context: This item tests multi-premise chaining and existence handling in categorical syllogisms. Universal inclusions can be chained; existential statements (“some …”) guarantee at least one element but do not force intersections with unrelated sets unless specified. Given Data / Assumptions: All Metals ⊆ Silver. All Silver ⊆ Diamond. Some Diamonds are Gold (∃x: x ∈ Diamond ∩ Gold). Some Gold are Marbles (∃y: y ∈ Gold ∩ Marbles). Concept / Approach: From universal chains A ⊆ B and B ⊆ C we infer A ⊆ C. “Some” statements assert existence but do not identify overlap with a given other subset unless a link is stated or deducible. Step-by-Step Solution: 1) Chain universals: Metals ⊆ Silver ⊆ Diamond ⇒ Metals ⊆ Diamond. So Conclusion II is necessarily true.2) Conclusion I (“Some gold are metals”): We only know some Diamonds are Gold. Metals are Diamonds, but nothing ensures that the particular Diamonds that are Gold are also Metals. Not entailed.3) Conclusion III (“Some silver are marble”): We know some Gold are Marbles and some Diamonds are Gold. That gives some Diamonds are Marbles, but Silver ⊆ Diamond does not imply any Silver is Marble. Not entailed.4) Conclusion IV (“Some gold are silver”): From “some Diamonds are Gold” and Silver ⊆ Diamond, Gold could intersect Silver or lie outside Silver entirely; not guaranteed. Verification / Alternative check: Create a model where Diamonds = {d1, d2}, Silver = {s1} with s1 = d1, Metals = {m1} with m1 = s1, Gold = {d2}, Marbles = {g1} with g1 = d2. All premises hold; only Conclusion II is forced. Why Other Options Are Wrong: Conclusions I, III, IV require overlaps not guaranteed by the premises. Common Pitfalls: Confusing “subset of Diamonds” with “equals the specific Diamonds that are Gold.” Existence in one region of a superset never forces existence in a particular subset unless stated. Final Answer: Only conclusion II follows.

Question 3

Statements: I. Some cats are dogs. II. No dog is a toy. Conclusions: I. Some dogs are cats. II. Some toys are cats. III. Some cats are not toys. IV. All toys are cats. Choose the option that must follow.

Accepted Answer

Introduction / Context: This question examines conversion of a particular affirmative and its interaction with a universal negative. We must determine which conclusions are logically necessary in all models consistent with the premises. Given Data / Assumptions: Premise 1: Some Cats are Dogs (∃x: x ∈ Cat ∩ Dog). Premise 2: No Dog is a Toy (Dog ∩ Toy = ∅). Concept / Approach: “Some A are B” entails the symmetric “Some B are A.” A universal negative about Dogs and Toys guarantees that any Dog cannot be a Toy. Combine these to deduce about the Cats that are Dogs. Step-by-Step Solution: 1) From “Some Cats are Dogs,” infer by symmetry: Some Dogs are Cats (Conclusion I is true).2) Those same cats that are dogs cannot be toys (from “No Dog is a Toy”). Therefore, at least some Cats are not Toys (Conclusion III is true).3) Conclusion II (“Some Toys are Cats”) is unsupported; the premises speak only about Dogs and Toys being disjoint, not about Toys intersecting Cats.4) Conclusion IV (“All Toys are Cats”) is far stronger than anything given and is not entailed. Verification / Alternative check: Model: Let Dogs = {d1}, Cats = {d1, c2}, Toys = {t1}. Premise 1 holds via d1; Premise 2 holds since Toys do not contain d1. Here, I and III hold; II and IV fail. Why Other Options Are Wrong: II and III: II is not forced. I and II: II is not forced. Only I: Misses III, which necessarily follows. Common Pitfalls: Assuming that Cats and Toys must overlap simply because Dogs are excluded from Toys. The premises do not impose any relation between Cats (that are not Dogs) and Toys. Final Answer: Only Conclusions I and III follow.

Question 4

Statements: • Some scales are pencils. • Some erasers are pencils. Conclusions: I. Some pencils are erasers. II. Some pencils are scales. Select the correct option.

Accepted Answer

Introduction / Context: Here, each premise is an existential statement about overlap with the class “pencils.” We must decide whether each claimed overlap is guaranteed. Given Data / Assumptions: Some Scales are Pencils ⇒ ∃x: x ∈ Scales ∩ Pencils. Some Erasers are Pencils ⇒ ∃y: y ∈ Erasers ∩ Pencils. Concept / Approach: When a premise says “Some X are P,” it already asserts the existence of pencils that are X. Therefore, each conclusion that restates the existence of pencils overlapping with the named set is immediately validated. Step-by-Step Solution: 1) From Premise 2, there exists at least one pencil that is an eraser ⇒ Conclusion I is true.2) From Premise 1, there exists at least one pencil that is a scale ⇒ Conclusion II is true.3) No contradiction arises by having both exist simultaneously; they could be distinct or the same object, but existence is sufficient. Verification / Alternative check: Model: Let Pencils = {p1, p2}, Scales = {p1}, Erasers = {p2}. Both premises hold; both conclusions are satisfied. Why Other Options Are Wrong: Options “Only I” and “Only II” incorrectly deny one guaranteed existential. “Neither” and “Data inadequate” ignore that each premise already provides the needed existence. Common Pitfalls: Thinking that to assert “Some pencils are erasers” we must compare Scales and Erasers with each other. We do not: each premise independently witnesses an element of Pencils. Final Answer: Both I and II follow.

Question 5

Statements: All cows are animals. All deers are cows. Conclusions: I. All deers are animals. II. All animals are cows. Choose the correct option.

Accepted Answer

Introduction / Context: This is a straightforward chain of universal affirmatives and a check for an invalid converse. Such questions reinforce that subset relations do not reverse. Given Data / Assumptions: Cows ⊆ Animals. Deers ⊆ Cows. Concept / Approach: Transitivity of subset: If Deers ⊆ Cows and Cows ⊆ Animals, then Deers ⊆ Animals. The converse statement “All Animals are Cows” does not follow from “All Cows are Animals.” Step-by-Step Solution: 1) Combine inclusions: Deers ⊆ Cows and Cows ⊆ Animals ⇒ Deers ⊆ Animals (Conclusion I true).2) Test Conclusion II: “All animals are cows” would require Animals ⊆ Cows, which is the converse of a given premise and is not logically implied. Verification / Alternative check: Model: Animals = {a1, a2}, Cows = {a1}, Deers = {a1}. Premises hold. But a2 ∈ Animals is not a cow, refuting Conclusion II while keeping I true. Why Other Options Are Wrong: “Only II” and “Both” assert a converse fallacy. “Neither” ignores the valid transitive implication. Common Pitfalls: Confusing subset with equality; “All Cows are Animals” does not say “only cows are animals.” Final Answer: Only conclusion I follows.

Question 6

Statements: • All chickens are birds. • Some chickens are hens. • Female birds lay eggs. Conclusions: I. All birds lay eggs. II. Some hens are birds. III. Some chickens are not hens. Select the option that must follow.

Accepted Answer

Introduction / Context: This syllogism blends universal and particular statements with a qualifier (“female”). The task is to avoid overgeneralization while recognizing secure existential consequences. Given Data / Assumptions: All Chickens ⊆ Birds. Some Chickens are Hens (∃x: x ∈ Chickens ∩ Hens). Female Birds lay eggs. By definition, hens are female chickens (hence female birds). Concept / Approach: From “Some Chickens are Hens” and “All Chickens are Birds,” we can assert existence of hens that are birds. The statement about egg-laying is restricted to female birds, so it does not license “All birds lay eggs.” Step-by-Step Solution: 1) Since Chickens ⊆ Birds and some Chickens are Hens, we have some Hens that are Birds ⇒ Conclusion II is true.2) Conclusion I (“All birds lay eggs”) overgeneralizes. Only female birds lay eggs; male birds do not. Therefore I is false.3) Conclusion III (“Some chickens are not hens”) is not forced. The premises allow all chickens to be hens or only some; there is no guarantee of a non-hen chicken. Verification / Alternative check: Model 1 (compatible): All chickens are hens. Then II is true, III is false. Model 2: Only some chickens are hens; II still true, but III may or may not be true depending on numbers. Because III is not necessary, it does not follow. Why Other Options Are Wrong: Options asserting I or III are incorrect because neither is entailed in every model. Common Pitfalls: Reading “female birds lay eggs” as “all birds lay eggs,” or assuming “some A are B” implies “some A are not B.” Both are classic errors. Final Answer: Only conclusion II follows.

Question 7

Statements: • All Americans are English-speaking. • No Eskimos are English-speaking. Conclusions: I. No Eskimos are Americans. II. No English-speakers are Eskimos. Choose the option that must follow.

Accepted Answer

Introduction / Context: This is a classic use of a universal affirmation combined with a universal exclusion to deduce two symmetric “no overlap” conclusions. Given Data / Assumptions: Americans ⊆ English-speakers. Eskimos ∩ English-speakers = ∅. Concept / Approach: If set X is a subset of Y and a third set Z has empty intersection with Y, then Z must also be disjoint from X. Also, “No Eskimos are English-speaking” is logically equivalent to “No English-speakers are Eskimos.” Step-by-Step Solution: 1) Because Americans ⊆ English-speakers and Eskimos share no members with English-speakers, Eskimos cannot be Americans. Conclusion I is true.2) The premise “No Eskimos are English-speaking” is symmetric: it also entails “No English-speakers are Eskimos.” Conclusion II is true. Verification / Alternative check: Suppose English-speakers = {e1, e2}, Americans = {e1}, Eskimos = {k1}. Then Americans ⊆ English-speakers and Eskimos disjoint from English-speakers; both conclusions hold. Why Other Options Are Wrong: Any option denying one of the conclusions contradicts the direct consequences of the premises. Common Pitfalls: Overlooking the symmetry of “No A are B.” The statement implies two identical non-overlap claims by swapping A and B. Final Answer: Both I and II follow.

Question 8

Statement: Cactus plants are fleshy but need least water. Conclusions: I. All fleshy plants are cactus. II. Cactus plants need least water. Select the correct option.

Accepted Answer

Introduction / Context: Single-statement syllogism questions test recognition of what is exactly stated versus what would be an illicit generalization beyond the given wording. Given Data / Assumptions: Given: “Cactus plants are fleshy but need least water.” Interpretation: This attributes two properties to cactus: being fleshy and needing very little water. Concept / Approach: From “X are Y,” we may only infer that members of X enjoy property Y. We cannot flip it to “All Y are X” unless explicitly stated. When the second clause asserts a property of cactus (needing least water), that conclusion may be repeated verbatim. Step-by-Step Solution: 1) Conclusion II restates a property directly asserted about cactus; therefore it follows.2) Conclusion I overgeneralizes from “cactus are fleshy” to “all fleshy plants are cactus,” which is a converse fallacy and is not entailed. Verification / Alternative check: Counterexample to I: Many fleshy plants (e.g., certain succulents) are not cactus. The statement gives no exclusivity. Why Other Options Are Wrong: “Both” includes the invalid converse. “Only I” is the converse error. “Neither” ignores the explicit truth of II. “Data inadequate” is incorrect because the statement is sufficient to affirm II. Common Pitfalls: Confusing “some X have Y” or “all X have Y” with “only X have Y.” The latter is much stronger and is not given. Final Answer: Only II follows.

Question 9

Statements: • All poets are day dreamers. • All painters are day dreamers. Conclusions: I. All painters are poets. II. Some day dreamers are not painters. Choose the option that must follow.

Accepted Answer

Introduction / Context: This problem features two universal subset claims into the same superset and asks for necessary relations between the two subsets and the complement region. Without extra premises, neither a subset inclusion between Painters and Poets nor guaranteed existence outside Painters can be asserted. Given Data / Assumptions: Poets ⊆ DayDreamers. Painters ⊆ DayDreamers. No statement about overlaps or existence beyond these inclusions. Concept / Approach: From two subsets contained in the same superset, nothing follows about the relation between the subsets unless additional information is provided. Also, conclusions that assert existence (“some … are not …”) require explicit or deducible witnesses. Step-by-Step Solution: 1) Conclusion I (“All painters are poets”) would require Painters ⊆ Poets, which is not given; both could be disjoint or overlapping within DayDreamers.2) Conclusion II (“Some day dreamers are not painters”) is not guaranteed. It might be that all day dreamers are painters, or that there exist non-painter day dreamers; both models satisfy the premises. Verification / Alternative check: Model A: DayDreamers = Painters (and Poets empty). Premises hold; Conclusion II fails. Model B: DayDreamers = Poets (and Painters empty). Premises hold; Conclusion II again fails. Therefore II is not necessary. Model C: DayDreamers includes many non-painters; here II would be true, showing it is contingent, not necessary. Why Other Options Are Wrong: Options asserting I or II assume information not present in the premises. Common Pitfalls: Inferring relations between two subsets just because they share a superset, and assuming existence of elements outside a subset without an existential claim. Final Answer: Neither I nor II follows.

Question 10

Statements: a) All children are students. b) All students are players. Conclusions: I. All cricketers are students. II. All children are players. Select the option that must follow.

Accepted Answer

Introduction / Context: This is the same transitivity pattern as similar items: two universal affirmatives chained to test whether a third inclusion necessarily holds. Given Data / Assumptions: Children ⊆ Students. Students ⊆ Players. Concept / Approach: Transitivity: If A ⊆ B and B ⊆ C, then A ⊆ C. Any conclusion about unrelated classes (e.g., Cricketers) is not entailed unless connected by premises. Step-by-Step Solution: 1) Chain: Children ⊆ Players ⇒ all children are players (Conclusion II true).2) “All cricketers are students” is unsupported; cricketers may or may not be students. Verification / Alternative check: Construct a countermodel where Cricketers are non-students while all children are students and students are players. Premises hold; Conclusion I fails. Why Other Options Are Wrong: Options asserting I or both are stronger than what premises license. Common Pitfalls: Importing real-world knowledge (e.g., “students often play cricket”), which is irrelevant to formal entailment. Final Answer: Only conclusion II follows.

Question 11

Statements: • All men are aggressive. • All children are aggressive. Conclusions: I. Men are children. II. Children are men. Choose the option that must follow.

Accepted Answer

Introduction / Context: In categorical syllogisms, two different groups can both be subsets of a larger group without implying any relationship between the two smaller groups. This problem checks whether learners can resist the temptation to infer an unwarranted link between “men” and “children” merely because both are included in the larger set “aggressive.” Given Data / Assumptions: Premise 1: All men are aggressive (Men ⊆ Aggressive). Premise 2: All children are aggressive (Children ⊆ Aggressive). No statement connects Men directly to Children. Concept / Approach: From A ⊆ C and B ⊆ C, we cannot infer A ⊆ B or B ⊆ A without additional premises. Set-inclusion chains only travel along stated links. Any conclusion that declares “Men are Children” or “Children are Men” would require an explicit premise relating those two sets, which we do not have. Step-by-Step Solution: 1) Translate: Men ⊆ Aggressive, Children ⊆ Aggressive.2) There is no premise of the form Men ⊆ Children or Children ⊆ Men.3) Therefore, both proposed conclusions (I and II) overreach beyond the information given and are not logically necessary. Verification / Alternative check: Construct Model A: Aggressive = {m1, m2, c1}, Men = {m1, m2}, Children = {c1}. Both premises hold; neither Men ⊆ Children nor Children ⊆ Men is true. A different Model B could make Men and Children disjoint or overlapping—either way, no subset relation is forced by the premises. Hence neither conclusion necessarily follows. Why Other Options Are Wrong: “Only I” or “Only II”: each asserts a subset link that is not given. “Both”: doubles the same error. “Data inadequate”: classical syllogism questions are evaluated for logical entailment; here the data are adequate to decide that neither conclusion is entailed. Common Pitfalls: Assuming that sharing a superset creates an inclusion between the subsets. Also, reading real-world connotations into “men” and “children” distracts from pure set logic. Final Answer: Neither conclusion I nor conclusion II follows.

Question 12

Statements: 1) All goats are cows. 2) All cows are animals. Conclusions: I. All goats are animals. II. All animals are goats. Choose the option that must follow.

Accepted Answer

Introduction / Context: This problem tests two essentials: (i) chaining universal affirmatives (“All A are B,” “All B are C”) and (ii) spotting the converse fallacy (reversing a subset statement). Given Data / Assumptions: Goats ⊆ Cows. Cows ⊆ Animals. Concept / Approach: Transitivity of subset: If A ⊆ B and B ⊆ C, then A ⊆ C. Conversely, from A ⊆ B we cannot infer B ⊆ A. The second conclusion is exactly that invalid reversal at a larger scale. Step-by-Step Solution: 1) Chain the inclusions: Goats ⊆ Cows and Cows ⊆ Animals ⇒ Goats ⊆ Animals. So Conclusion I is guaranteed.2) Conclusion II (“All Animals are Goats”) would require Animals ⊆ Goats. That is a converse of an inclusion we do not have; it is not entailed. Verification / Alternative check: Model: Animals = {cow1, dog1}, Cows = {cow1}, Goats = {goat1} with goat1 = cow1. Premises hold, I is true (goat1 is an animal). However, dog1 is an animal but not a goat, falsifying II. Hence only I follows. Why Other Options Are Wrong: “Both” includes the converse fallacy; “Only II” is just the converse fallacy. “Neither” ignores the valid transitive implication. Common Pitfalls: Equating subset with equality. “All goats are cows” does not mean “only goats are cows,” and certainly not that “all animals are goats.” Final Answer: Only Conclusion I follows.

Question 13

Statements: • Some cars are buses. • All cars are caves. Conclusions: I. Some caves are not buses. II. Some caves are buses. III. No cave is a bus. IV. Some caves are cars. Select the option that must follow.

Accepted Answer

Introduction / Context: This question pairs one existential overlap with a universal inclusion. We must track how elements propagate through inclusions to evaluate what necessarily holds about the larger set “caves.” Given Data / Assumptions: Premise 1: Some Cars are Buses (∃x ∈ Cars ∩ Buses). Premise 2: All Cars are Caves (Cars ⊆ Caves). Concept / Approach: If all Cars are Caves, then every car— including those that are buses— is also a cave. Therefore, the intersection established in Premise 1 immediately gives an intersection within Caves. Separately, “Some caves are cars” follows because all cars are caves and there exists at least one car (witnessed by Premise 1). Step-by-Step Solution: 1) From “Some Cars are Buses,” pick witness c1 ∈ Cars ∩ Buses.2) From “All Cars are Caves,” c1 ∈ Caves. Therefore, c1 ∈ Caves ∩ Buses ⇒ Conclusion II is true (Some Caves are Buses).3) Because at least one Car exists, and all Cars are Caves, it follows that Some Caves are Cars ⇒ Conclusion IV is true.4) Conclusion I (“Some Caves are not Buses”) is not forced; it could be that every cave is a bus, or not— the premises do not settle this.5) Conclusion III (“No Cave is a Bus”) directly contradicts II and cannot be true in all models. Verification / Alternative check: Model: Let Cars = {c1}, Buses = {c1}, Caves = {c1, c2}. All Cars are Caves; Some Cars are Buses. Then II and IV hold; I might or might not hold depending on whether c2 is a bus— hence I is not necessary. III is false. Why Other Options Are Wrong: Any option that includes I or III claims something not guaranteed by the premises or contradicts them. Common Pitfalls: Confusing “All Cars are Caves” with “Only Cars are Caves,” and assuming extra information about Buses outside what is asserted. Final Answer: Only Conclusions II and IV follow.

Question 14

Statements: 1) Some girls are stars. 2) Meena is a girl. Conclusions: I. Meena is a star. II. Some stars are not girls. Choose the option that must follow.

Accepted Answer

Introduction / Context: Here we mix a particular statement about the class of girls with a singular statement about an individual (Meena). The challenge is to distinguish what is guaranteed from what merely could be true. Given Data / Assumptions: Some Girls are Stars: ∃x ∈ Girls ∩ Stars. Meena ∈ Girls. Concept / Approach: From “Some Girls are Stars” we know at least one girl is a star, but we do not know which girl. Without a premise linking Meena to the specific subset of star-girls, we cannot affirm that Meena is a star. Likewise, statements about stars outside the class of girls need dedicated evidence. Step-by-Step Solution: 1) Conclusion I (“Meena is a star”): The witness for “some girls are stars” could be someone other than Meena. Hence I is not necessary.2) Conclusion II (“Some stars are not girls”): Nothing indicates stars outside Girls. It could be that all stars are girls or that some are not— the premises are silent. Therefore II is not necessary. Verification / Alternative check: Model A: Girls = {Meena, G2}; Stars = {G2}. Premises hold; I is false; II may or may not be true depending on whether there exist non-girl stars. Model B: Stars = {Meena}; then I true and II false. Because truth values can vary while premises remain true, neither conclusion follows necessarily. Why Other Options Are Wrong: Any option asserting I or II assumes information not fixed by the premises. Common Pitfalls: Equating “some” with a specific named individual and assuming outside elements without explicit evidence. Final Answer: Neither Conclusion I nor II follows.

Question 15

Statements: 1) Some teachers are followers. 2) Some followers are famous. Conclusions: I. Some teachers are famous. II. Some followers are teachers. Choose the option that must follow.

Accepted Answer

Introduction / Context: Two “some” premises can be tricky because they establish existence but not necessarily intersection between the specific subsets mentioned. The test is to see whether we can deduce overlap where it is warranted and avoid it where it is not. Given Data / Assumptions: Some Teachers are Followers (∃x ∈ Teachers ∩ Followers). Some Followers are Famous (∃y ∈ Followers ∩ Famous). Concept / Approach: Conclusion II is directly supported: from the first premise, there exist followers who are teachers. But Conclusion I would require that at least one of the followers who is a teacher is also among the followers who are famous— which the premises do not guarantee. Step-by-Step Solution: 1) From Premise 1, pick t1 ∈ Teachers ∩ Followers. This witnesses Conclusion II: “Some Followers are Teachers.”2) Premise 2 provides some follower f1 ∈ Followers ∩ Famous. The premises do not assert t1 = f1, so we cannot claim a teacher who is famous.3) Therefore, Conclusion I is not necessary, while II is. Verification / Alternative check: Model: Followers = {t1, f1}; Teachers = {t1}; Famous = {f1}. Both premises hold. II is true (t1 is a follower-teacher), but I is false (no teacher is famous). Hence only II follows. Why Other Options Are Wrong: Claims that I follows assume the same element witnesses both premises; the data do not enforce that. “Both” overstates; “Neither” understates. Common Pitfalls: Assuming that two separate existential statements necessarily refer to the same individual. That coincidence is not guaranteed. Final Answer: Only Conclusion II follows.

Question 16

Statements: • Many books are rocks. • All rocks are clips. Conclusions: I. Some books are clips. II. No rock is a book. Choose the option that must follow.

Accepted Answer

Introduction / Context: Here a quantified existential (“many” which implies “some”) combines with a universal inclusion. We must transfer membership through the inclusion and also test a negation claim against the premises. Given Data / Assumptions: “Many Books are Rocks” ⇒ at least one book is a rock (∃x ∈ Books ∩ Rocks). All Rocks ⊆ Clips. Concept / Approach: If some book is a rock and every rock is a clip, then that specific book is also a clip. Conversely, “No rock is a book” contradicts the existential information provided by “many books are rocks.” Step-by-Step Solution: 1) Pick witness b1 ∈ Books ∩ Rocks.2) From Rocks ⊆ Clips, b1 ∈ Clips. Therefore, Some Books are Clips ⇒ Conclusion I holds.3) Conclusion II (“No rock is a book”) is incompatible with b1 ∈ Books ∩ Rocks and is therefore false. Verification / Alternative check: Model: Rocks = {r1, r2}, Books = {b1} with b1 = r1, Clips = {r1, r2, c1}. All premises hold. Conclusion I is satisfied by b1, while II is negated by the same witness. Why Other Options Are Wrong: “Both” is impossible (II contradicts the premises). “Only II” contradicts the existential. “Neither” ignores the logical consequence. Common Pitfalls: Overlooking that “many” at least means “some,” which is enough to carry through universal inclusions. Final Answer: Only Conclusion I follows.

Question 17

Statements: • No man is a donkey. • Ajay is a man. Conclusions: I. Ajay is not a donkey. II. All men are not Ajay. Choose the option that must follow.

Accepted Answer

Introduction / Context: Universal negatives like “No A are B” block any overlap between the two sets. When a specific individual belongs to one set, the negative immediately transfers to that individual. Ambiguous linguistic forms like “All men are not Ajay” must be handled cautiously in formal logic. Given Data / Assumptions: No Man is a Donkey (Man ∩ Donkey = ∅). Ajay ∈ Man. Concept / Approach: If a person (Ajay) is in the set of Men, and Men share no members with Donkeys, then Ajay cannot be a Donkey. The second conclusion’s natural-language phrasing is not a standard syllogistic form and typically reads as either a trivial identity statement (“not all men are Ajay”) or an ill-formed universal about identity, neither of which follows from the premises in the way syllogism options intend. Step-by-Step Solution: 1) From Ajay ∈ Man and Man ∩ Donkey = ∅, conclude Ajay ∉ Donkey ⇒ Conclusion I is true.2) Conclusion II asserts something about all men and the identity “Ajay.” The premises do not discuss identity partitions; hence II is not entailed. Verification / Alternative check: Model: Men = {Ajay, M2}, Donkeys = {D1}. Disjointness holds; Ajay is not a donkey (I true). There is no basis to claim a universal sentence about “All men are not Ajay” as a logical consequence— it is outside syllogistic scope. Why Other Options Are Wrong: Any option including II attributes content beyond the premises. “Neither” ignores the direct consequence that Ajay is not a donkey. Common Pitfalls: Misreading awkward English phrasing as a valid categorical proposition. Stick to set relations established by the premises. Final Answer: Only Conclusion I follows.

Question 18

Statements: • Some kings are queens. • All queens are beautiful. Conclusions: I. All kings are beautiful. II. All queens are kings. Choose the option that must follow.

Accepted Answer

Introduction / Context: This item mixes a particular affirmative with a universal inclusion to test overgeneralization. From “some kings are queens” and “all queens are beautiful,” we can indeed infer “some kings are beautiful,” but neither of the offered conclusions matches that weaker, correct statement. Given Data / Assumptions: Some Kings are Queens (∃x ∈ Kings ∩ Queens). All Queens ⊆ Beautiful. Concept / Approach: Because all queens are beautiful, any king who is also a queen is beautiful. That yields “some kings are beautiful,” not “all kings are beautiful.” The second conclusion, “All queens are kings,” is a converse of the first premise and is not entailed. Step-by-Step Solution: 1) Take witness k1 ∈ Kings ∩ Queens. From Queens ⊆ Beautiful, k1 ∈ Beautiful.2) Therefore, “some kings are beautiful” is true. But Conclusion I states “all kings are beautiful,” which is stronger and unjustified.3) Conclusion II (“All queens are kings”) is a universalization not supported by “some kings are queens.” Verification / Alternative check: Model: Kings = {k1, k2}, Queens = {k1}, Beautiful = all queens ∪ others. Premises hold. I is false if k2 is not beautiful; II is false if there exists a queen not among kings in another model. Thus neither conclusion is necessary. Why Other Options Are Wrong: “Either … or …” suggests exactly one is forced; but we can build models where both fail, so option C is incorrect. “Both” obviously overstates. Common Pitfalls: Upgrading “some” to “all,” and confusing a statement with its converse. Final Answer: Neither Conclusion I nor Conclusion II follows.

Question 19

Statements: 1) All goats are tigers. 2) All tigers are lions. Conclusions: I. All tigers are goats. II. All lions are tigers. III. No goat is a lion. IV. No lion is a goat. Choose the option that must follow.

Accepted Answer

Introduction / Context: A pair of chained universal affirmatives places one class inside another and then inside a third. The conclusions tempt you with converses and absolute negatives. We must evaluate each against the actual chain. Given Data / Assumptions: Goats ⊆ Tigers. Tigers ⊆ Lions. Therefore, Goats ⊆ Lions (by transitivity). Concept / Approach: From A ⊆ B and B ⊆ C, we may derive A ⊆ C, but we cannot reverse them to B ⊆ A or C ⊆ B. Also, “No A are C” is directly contradicted when we have A ⊆ C unless A is empty (which is not asserted here). Step-by-Step Solution: 1) Conclusion I (“All tigers are goats”) is the converse of “All goats are tigers”; it is not entailed.2) Conclusion II (“All lions are tigers”) is the converse of “All tigers are lions”; not entailed.3) Conclusion III (“No goat is a lion”) contradicts the chain Goats ⊆ Lions; unless Goats were empty (not stated), this is false.4) Conclusion IV (“No lion is a goat”) is also false because at least those goats are lions; hence some lions are goats. Verification / Alternative check: Model: Let Goats = {g1}, Tigers = {g1, t2}, Lions = {g1, t2, l3}. Both premises hold. I fails (t2 is a tiger but not a goat), II fails (l3 is a lion but not a tiger), III fails (g1 is a goat and a lion), IV fails (g1 is a lion and a goat). Hence none of the conclusions follows. Why Other Options Are Wrong: Options claiming any of I–IV follow contradict either the chain or commit converse errors. Common Pitfalls: Reversing subset statements and assuming disjointness where inclusion is given. Final Answer: None of the Conclusions follows.

Question 20

Statements: • Some cats are dogs. • All dogs are black. Conclusions: I. Some cats are black. II. Some dogs are black. Choose the option that must follow.

Accepted Answer

Introduction / Context: Combining a particular overlap with a universal property often yields two distinct necessary consequences: one about the particular elements involved and one about the whole class under the universal statement. Given Data / Assumptions: Some Cats are Dogs (∃x ∈ Cats ∩ Dogs). All Dogs are Black (Dogs ⊆ Black). Concept / Approach: Take the witnessed cat–dog individual; because all dogs are black, that same individual is black. Therefore “some cats are black.” Separately, “all dogs are black” implies “some dogs are black,” provided at least one dog exists— and existence is guaranteed by the first premise. Step-by-Step Solution: 1) From “Some Cats are Dogs,” pick witness c1 ∈ Cats ∩ Dogs.2) Since Dogs ⊆ Black, c1 ∈ Black, yielding “Some Cats are Black” ⇒ Conclusion I true.3) The existence of c1 establishes that at least one dog exists. With Dogs ⊆ Black, it follows that “Some Dogs are Black” ⇒ Conclusion II true. Verification / Alternative check: Model: Dogs = {d1}, Cats = {d1, c2}, Black = universal set. Premises hold. Both conclusions hold, witnessed by d1 (who is both a cat and a black dog). Why Other Options Are Wrong: Any option denying I or II contradicts direct, necessary consequences of the premises. “Data inadequate” is incorrect because the first premise supplies the needed existence. Common Pitfalls: Forgetting to use the existence guaranteed by “some” to justify that at least one dog (hence a black dog) exists. Final Answer: Both Conclusions I and II follow.

Syllogism Questions