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Maharashtra HSC Logic study materials
Maharashtra HSC Logic study resources

Maharashtra HSC Logic practice questions

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Question 1Nature and Scope of Logic

In the traditional Indian classification of philosophy, the schools that accept the authority of the Vedas are collectively called which of the following?

  1. Nāstika schools
  2. Āstika schools Correct answer.
  3. Cārvāka schools
  4. Lokāyata schools

Explanation

Indian philosophical schools are traditionally divided by whether they accept Vedic authority. Those that do are āstika; those that reject it are nāstika. Nyāya, which developed a systematic science of reasoning, belongs among the āstika schools.

Question 2Nature and Scope of Logic

Aristotle's logical writings were grouped by later commentators under which title?

  1. The Metaphysics
  2. The Organon Correct answer.
  3. The Ethics
  4. The Rhetoric

Explanation

Later editors collected Aristotle's treatises on terms, propositions, syllogism and demonstration under the name Organon, meaning 'instrument'. The title reflects the view that logic is the instrument of all inquiry rather than a branch of substantive knowledge.

Question 3Nature and Scope of Logic

Which statement best captures the traditional definition of logic as a normative science?

  1. Logic measures the speed of human reasoning
  2. Logic describes how people happen to think in everyday life
  3. Logic catalogues the psychological causes of belief
  4. Logic studies the ideal standards that correct thinking ought to satisfy Correct answer.

Explanation

Logic is normative because it prescribes norms of validity and consistency rather than merely recording actual habits of thought. A descriptive science of thinking as it occurs belongs to psychology. This distinction between 'ought' and 'is' is central to the scope of logic.

Question 4Nature and Scope of Logic

The term 'logic' is derived from which Greek word?

  1. Physis
  2. Arete
  3. Logos Correct answer.
  4. Sophia

Explanation

'Logic' comes from logos, which carries senses such as word, reason, account and principle. This etymology connects logic with reasoned discourse rather than with mere feeling. Sophia means wisdom, arete excellence, and physis nature.

Question 5Nature and Scope of Logic

Which pair correctly names the two branches that study reasoning as form and reasoning as it occurs in actual argument?

  1. Rhetoric and grammar
  2. Formal logic and informal logic Correct answer.
  3. Epistemology and ontology
  4. Ethics and aesthetics

Explanation

Formal logic abstracts from content and examines the structure of arguments, while informal logic attends to arguments as used in natural language and everyday contexts. The other pairs name different philosophical or linguistic disciplines.

Question 6Nature and Scope of Logic

A student says that since logic studies correct reasoning, it tells us which particular factual claims are true. Which criticism of this view is most accurate?

  1. Logic guarantees truth because valid arguments cannot have false premises
  2. Logic deals only with mathematical propositions
  3. Logic is concerned solely with the meaning of words
  4. Logic supplies the norms of valid inference but cannot by itself establish the truth of premises Correct answer.

Explanation

Logic evaluates the connection between premises and conclusion, not the factual truth of the premises themselves. A valid argument may still lead to a false conclusion if a premise is false. Establishing premises is the work of the relevant special sciences or experience.

Question 7Nature and Scope of Logic

In the Indian tradition, which school is especially known for developing a systematic theory of inference (anumāna) with a five-membered syllogism?

  1. Vedānta
  2. Nyāya Correct answer.
  3. Mīmāṃsā
  4. Sāṅkhya

Explanation

Nyāya developed an elaborate epistemology in which inference is a principal means of knowledge, presented in a five-membered scheme of thesis, reason, example, application and conclusion. The other schools pursued different central concerns such as cosmology, ritual interpretation or metaphysics.

Question 8Nature and Scope of Logic

Which of the following best expresses why logic is called a 'science of sciences' in classical tradition?

  1. It is the oldest of all the sciences
  2. It supplies the method of valid reasoning that every science presupposes Correct answer.
  3. It replaces all other sciences with its own conclusions
  4. It is the only science that uses language

Explanation

The title reflects logic's role as a general instrument: any discipline that reasons from evidence to conclusions relies on the norms logic articulates. It does not generate the substantive findings of other sciences. Hence it is foundational rather than rival to them.

Question 9Nature and Scope of Logic

A candidate argues: 'Every branch of study with a subject matter is a science; logic has a subject matter; therefore logic is a science.' Which feature of this argument makes it a piece of applied logical reasoning rather than a statement about logic's definition?

  1. It uses a general premise and a particular premise to draw a conclusion Correct answer.
  2. It contains the word 'science'
  3. It is written in ordinary language
  4. It makes a claim about branches of study

Explanation

The argument has the structure of a categorical syllogism: a universal premise, a singular premise and a conclusion. Recognising that pattern is an exercise in applying logical form. The vocabulary and language of the argument are incidental to its form.

Question 10Nature and Scope of Logic

Which distinction correctly separates the material object from the formal object of logic?

  1. Material object is truth; formal object is beauty
  2. Material object is language; formal object is mathematics
  3. Material object is the mind; formal object is the brain
  4. Material object is thought as such; formal object is thought considered as subject to the laws of valid inference Correct answer.

Explanation

The material object of a science is the general field it studies, while the formal object is the specific aspect under which it studies that field. For logic the field is thought or discourse, and the aspect is its correctness or validity. This is why logic does not duplicate psychology.

Question 11Nature and Scope of Logic

Which of these is the best example of a second-order or meta-logical question?

  1. Is modus ponens a valid argument form?
  2. How many figures does a categorical syllogism have?
  3. Are the laws of logic themselves revisable? Correct answer.
  4. What are the truth conditions of a conjunction?

Explanation

Meta-logical questions concern the status, justification and possible revisability of logical principles themselves rather than the validity of particular forms. Asking whether logical laws can be revised stands back from using those laws. The other options are first-order questions within logic.

Question 12Nature and Scope of Logic

A thinker holds that logic is purely a description of how the human mind in fact operates. Which consequence most clearly conflicts with the traditional scope of logic?

  1. It makes logical laws depend on empirical psychology and so unable to criticise faulty reasoning as incorrect Correct answer.
  2. It restricts logic to the study of language
  3. It denies that logic has any subject matter at all
  4. It makes logic too abstract for practical use

Explanation

If logical laws merely describe actual mental operations, then a widespread pattern of faulty reasoning would count as correct. The normative force of logic, its power to judge reasoning as valid or invalid, would be lost. Hence psychologism is rejected by the traditional account.

Question 13Nature and Scope of Logic

Which statement about the relation between logic and epistemology is most defensible?

  1. Logic and epistemology are identical because both study knowledge
  2. Epistemology is a branch of formal logic
  3. Logic is irrelevant to questions of justification
  4. Logic provides norms of inference that epistemology employs when assessing justification Correct answer.

Explanation

Epistemology asks what knowledge and justified belief are, and in answering it relies on canons of inference that logic supplies. Logic itself does not define knowledge. The two disciplines are therefore distinct but interdependent.

Question 14Nature and Scope of Logic

The traditional division of logic into 'material' and 'formal' logic corresponds most closely to which contrast?

  1. The study of language versus the study of mathematics
  2. The study of ancient versus modern logic
  3. The study of necessity versus the study of probability
  4. The study of the content and truth of propositions versus the study of their structure Correct answer.

Explanation

Material logic concerns the content, truth and adequacy of premises, while formal logic concerns the structural relations that make inference valid. This echoes the distinction between the matter and form of an argument. It is not a historical or disciplinary contrast.

Question 15Nature and Scope of Logic

Which of the following is a legitimate reason for saying that logic is a science rather than an art?

  1. It is taught in schools
  2. It requires practice and skill in application
  3. It consists of a body of systematic, ordered knowledge with its own principles and laws Correct answer.
  4. It uses symbols

Explanation

A science, in the classical sense, is an organised body of knowledge organised around principles. Logic qualifies because it formulates and systematises laws of valid inference. Skill in applying those laws makes logic an art as well, but its scientific character rests on its systematic body of principles.

Question 16Nature and Scope of Logic

Which of the following historical developments is most closely associated with the emergence of modern symbolic logic?

  1. The compilation of the Organon
  2. The work of Frege and Russell on formal languages and foundations Correct answer.
  3. The medieval theory of supposition
  4. The composition of the Nyāya Sūtras

Explanation

Modern symbolic logic arose with the development of precise formal languages and the analysis of mathematics in the work of Frege, Russell and their successors. This marked a shift from the syllogistic tradition to a far more expressive formalism. The other options belong to earlier periods.

Question 17Nature and Scope of Logic

A textbook remarks that logic is 'the science of the possible as such'. Which reading of this remark is most consistent with logic's scope?

  1. Logic studies the forms of consistency and consequence that hold independently of what happens to exist Correct answer.
  2. Logic studies probability distributions
  3. Logic studies what people believe to be possible
  4. Logic studies what is possible in the physical world

Explanation

Logic is concerned with what follows from what, and this holds across all possible situations, not only the actual one. Its laws do not depend on contingent facts about the physical world or on anyone's beliefs. This is why logical truths are often described as necessary.

Question 18Nature and Scope of Logic

Which statement correctly distinguishes a 'law of thought' from a 'law of logic' in the traditional debate?

  1. Laws of logic are descriptive; laws of thought are prescriptive
  2. Laws of thought describe psychological regularities; laws of logic prescribe norms of valid inference Correct answer.
  3. They are exactly the same thing in every respect
  4. Laws of thought are mathematical; laws of logic are linguistic

Explanation

The traditional debate separates descriptive psychological generalisations about how we think from normative principles governing what counts as valid inference. Identifying laws of logic with laws of thought is precisely what the normative account resists. Hence the distinction preserves logic's critical function.

Question 19Nature and Scope of Logic

In a discussion of the scope of logic, a student claims that because logic is formal it must be indifferent to meaning. Which qualification is most accurate?

  1. Formal logic applies only to artificial languages
  2. Formal logic is concerned only with the length of sentences
  3. Formal logic ignores all meaning whatsoever
  4. Formal logic abstracts from particular content but still depends on the meanings of logical constants Correct answer.

Explanation

Formal logic abstracts from the specific subject matter of arguments, but its validity conditions depend on the meanings of logical constants such as 'and', 'or' and 'not'. It is not a theory of syntax alone. This qualification reconciles formality with meaning-sensitivity.

Question 20Nature and Scope of Logic

Which of the following best illustrates the practical utility of logic within the scope of the Maharashtra HSC course?

  1. Measuring the length of an argument
  2. Detecting a fallacy in a newspaper editorial by examining the inferential link Correct answer.
  3. Counting the number of words in a premise
  4. Memorising the dates of philosophers

Explanation

The practical value of logic lies in evaluating real reasoning, for example by identifying when a conclusion does not follow from the premises given. This is an application of logical analysis to everyday discourse. The other options involve no assessment of inference.

Question 21Basic Concepts of Logic: Terms, Propositions and Arguments

In logic, which of the following is the best example of a term used in the strict logical sense?

  1. 'Because' as a word joining two clauses
  2. 'Maharashtra' as a word that names a particular state Correct answer.
  3. 'Alas' as a word expressing sorrow
  4. 'Quickly' as a word describing how an action is done

Explanation

A term, strictly, is a word or group of words that can serve as the subject or predicate of a proposition, i.e. it can stand for something and be affirmed or denied of something. 'Maharashtra' names an individual and can function as a subject, so it qualifies as a term. Adverbs, conjunctions and interjections do not function as subjects or predicates of propositions.

Question 22Basic Concepts of Logic: Terms, Propositions and Arguments

Which characteristic distinguishes a proposition from a mere question or command?

  1. It is capable of being true or false Correct answer.
  2. It must begin with a proper noun
  3. It is always written in the present tense
  4. It contains at least three words

Explanation

A proposition is a statement that asserts something and is therefore capable of truth or falsity. Questions and commands may be grammatical sentences, but they do not assert anything, so truth value does not apply to them. Length, tense and the type of noun used are irrelevant to propositional status.

Question 23Basic Concepts of Logic: Terms, Propositions and Arguments

An argument in logic consists of which components?

  1. Premises offered as support together with a conclusion Correct answer.
  2. A conclusion alone, stated clearly
  3. Two or more conclusions linked together
  4. A definition followed by an example

Explanation

An argument is a group of propositions in which some, the premises, are claimed to provide support for another, the conclusion. Both parts are required: without premises there is nothing to support the conclusion. A definition with an example illustrates meaning but makes no claim of support.

Question 24Basic Concepts of Logic: Terms, Propositions and Arguments

The word 'Socrates' in the proposition 'Socrates is wise' functions logically as which of the following?

  1. A quantifier
  2. A propositional connective
  3. A singular term Correct answer.
  4. A copula

Explanation

'Socrates' names one specific individual and therefore serves as a singular term in subject position. The copula is the linking word 'is', not the name. Quantifiers such as 'all' or 'some' and connectives such as 'and' or 'or' play entirely different roles.

Question 25Basic Concepts of Logic: Terms, Propositions and Arguments

Which pair correctly matches a proposition with its truth value when the proposition is 'All triangles have three sides'?

  1. The proposition is false, because some triangles are drawn imperfectly
  2. The proposition is neither true nor false, because it is general
  3. The proposition is true, because the predicate is contained in the meaning of the subject Correct answer.
  4. The proposition is true only when someone believes it

Explanation

'All triangles have three sides' is an analytic truth: having three sides belongs to the very definition of a triangle. Truth value belongs to the proposition itself, not to anyone's belief about it. Imperfect drawings and the generality of the statement do not affect its truth.

Question 26Basic Concepts of Logic: Terms, Propositions and Arguments

In the argument 'All metals expand on heating; copper is a metal; therefore copper expands on heating', which proposition is the conclusion?

  1. Copper expands on heating Correct answer.
  2. No proposition here is a conclusion
  3. All metals expand on heating
  4. Copper is a metal

Explanation

The conclusion is the proposition that the other propositions are offered to establish, usually signalled by 'therefore'. Here the first two propositions supply the grounds and the third is what follows from them. The first two are premises, not the conclusion.

Question 27Basic Concepts of Logic: Terms, Propositions and Arguments

Which of the following best explains why logic studies the form of arguments rather than only their content?

  1. Because the subject matter of an argument determines whether its form is valid
  2. Because arguments with the same form stand or fall together regardless of subject matter Correct answer.
  3. Because formal arguments always have true premises
  4. Because content is never relevant to whether a conclusion follows

Explanation

Logic abstracts from subject matter to patterns of reasoning: if a form is valid, every argument of that form with true premises has a true conclusion. This is why the same pattern can be recognised in arguments about geometry, law or chemistry. Content still matters for assessing whether premises are actually true.

Question 28Basic Concepts of Logic: Terms, Propositions and Arguments

Consider 'Some students are not attentive'. Which classification of this proposition is correct?

  1. Universal negative
  2. Particular negative Correct answer.
  3. Singular affirmative
  4. Universal affirmative

Explanation

The proposition is particular because 'some' indicates that it speaks of part of the class, and negative because it denies attentiveness of those students. In traditional notation it is an O proposition. Universal propositions use 'all' or 'no', and singular propositions concern one named individual.

Question 29Basic Concepts of Logic: Terms, Propositions and Arguments

Which change turns the sentence 'The library is open' into a different proposition rather than the same proposition reworded?

  1. Rewording it as 'The library is not closed' Correct answer.
  2. Rewording it as 'It is open, that library'
  3. Translating it into Marathi with the same meaning
  4. Writing it as 'The library is open.' with a full stop

Explanation

A proposition is identified by the claim it makes, so paraphrase preserving that claim yields the same proposition. 'The library is not closed' makes a different claim, since a library could be neither open nor closed (for example, closed for renovation). Punctuation, translation and word order do not change the proposition asserted.

Question 30Basic Concepts of Logic: Terms, Propositions and Arguments

In 'The book on the table belongs to Ravi', the phrase 'on the table' functions as which of the following?

  1. A separate premise supporting the conclusion
  2. A part of the subject term that qualifies it Correct answer.
  3. A quantifier governing the subject
  4. The copula linking subject and predicate

Explanation

The complete subject term is 'the book on the table', in which the descriptive phrase restricts which book is meant. Such qualifying phrases are part of the term rather than independent propositions. The copula here is 'belongs to', and no quantifier is present.

Question 31Basic Concepts of Logic: Terms, Propositions and Arguments

Which of the following is an argument rather than a mere explanation?

  1. Since all citizens have equal rights, and she is a citizen, she has equal rights Correct answer.
  2. The plant wilted because it was not watered for a week
  3. Water boils at 100 degrees Celsius at sea level
  4. Read the chapter carefully before the test

Explanation

An argument offers premises as grounds for accepting a conclusion, typically with inference indicators such as 'since' and 'therefore'. The other options give a causal account, a factual statement and a command, none of which presents premises supporting a conclusion.

Question 32Basic Concepts of Logic: Terms, Propositions and Arguments

The proposition 'No reptiles are warm-blooded' is best described by which traditional classification?

  1. A: universal affirmative
  2. E: universal negative Correct answer.
  3. I: particular affirmative
  4. O: particular negative

Explanation

The word 'no' denies the predicate of the entire subject class, which makes the proposition universal and negative, traditionally labelled E. Universal affirmative propositions use 'all', while particular propositions use 'some'. The quantity and quality together fix the classification.

Question 33Basic Concepts of Logic: Terms, Propositions and Arguments

Which feature shows that 'If it rains, the match will be cancelled' is a compound proposition?

  1. It expresses a command
  2. It contains a proper noun
  3. It has a single subject and predicate
  4. It contains two component propositions joined by a connective Correct answer.

Explanation

A compound proposition is built from simpler propositions joined by truth-functional connectives such as 'if ... then', 'and' or 'or'. Here 'it rains' and 'the match will be cancelled' are combined by the conditional connective. A categorical proposition, by contrast, has one subject and one predicate.

Question 34Basic Concepts of Logic: Terms, Propositions and Arguments

In the argument 'Either the fuse is blown or the bulb is faulty. The fuse is not blown. So the bulb is faulty', what role does 'Either the fuse is blown or the bulb is faulty' play?

  1. It is an implicit definition
  2. It is a premise of the argument Correct answer.
  3. It is the conclusion of the argument
  4. It is an explanation of the conclusion

Explanation

The disjunctive proposition states one of the grounds from which the conclusion is drawn, so it is a premise. Together with the second premise denying one disjunct, it supports the conclusion that the bulb is faulty. The conclusion is the final proposition, not the opening disjunction.

Question 35Basic Concepts of Logic: Terms, Propositions and Arguments

Which statement about the relation between sentences and propositions is correct?

  1. Two different sentences can express the same proposition Correct answer.
  2. Only declarative sentences can ever be used to express a proposition
  3. Every sentence expresses exactly one proposition
  4. A proposition cannot be expressed by more than one sentence

Explanation

Propositions are what sentences assert, so distinct sentences, including sentences in different languages, can express one and the same proposition. Conversely, a single sentence containing ambiguity may express more than one proposition. Declarative sentences are the standard vehicle, but the identity of a proposition is not tied to one wording.

Question 36Basic Concepts of Logic: Terms, Propositions and Arguments

A student writes: 'All poets are imaginative; some imaginative people are careless; therefore all poets are careless.' Which description of this argument is accurate?

  1. The premises are true and the conclusion follows necessarily
  2. The premises are false and the conclusion follows necessarily
  3. The premises are true but the conclusion does not follow necessarily Correct answer.
  4. The premises are false and the conclusion does not follow necessarily

Explanation

The middle term 'imaginative' is undistributed in both premises, so the conclusion about all poets does not follow; careless people may be imaginative without being poets. The premises themselves can be granted as true. This illustrates that true premises do not guarantee a true conclusion when the form is invalid.

Question 37Basic Concepts of Logic: Terms, Propositions and Arguments

Which of the following best captures the difference between validity and truth in logic?

  1. Validity concerns the relation between premises and conclusion, truth concerns individual propositions Correct answer.
  2. Validity requires true premises, truth requires a valid argument
  3. Validity and truth are the same property applied to arguments and propositions respectively
  4. Validity concerns individual propositions, truth concerns the relation between them

Explanation

Validity is a property of arguments: it says that if the premises were true the conclusion would have to be true. Truth is a property of individual propositions. An argument can be valid with false premises, and an argument with true premises can be invalid.

Question 38Basic Concepts of Logic: Terms, Propositions and Arguments

In the proposition 'All diligent students pass the examination', which term is distributed?

  1. Only the predicate term
  2. Both subject and predicate terms
  3. Only the subject term Correct answer.
  4. Neither term

Explanation

In a universal affirmative proposition the subject term is distributed because the predicate is affirmed of every member of the subject class. The predicate is undistributed because the statement says nothing about all who pass. Distribution concerns whether a term is taken over its whole extension.

Question 39Basic Concepts of Logic: Terms, Propositions and Arguments

Which pair of words most reliably signals that a proposition is functioning as a conclusion?

  1. 'Because' and 'since'
  2. 'Suppose' and 'assume'
  3. 'Therefore' and 'hence' Correct answer.
  4. 'And' and 'also'

Explanation

Inference indicators such as 'therefore', 'hence', 'so' and 'thus' precede or introduce the conclusion. Words like 'because' and 'since' typically introduce premises. Recognizing such indicators helps reconstruct an argument's structure.

Question 40Basic Concepts of Logic: Terms, Propositions and Arguments

A term is said to be 'empty' or 'non-referring' when which condition holds?

  1. It appears only in the predicate position
  2. It is written with a capital letter
  3. Nothing in the actual world falls under it Correct answer.
  4. It has more than one meaning in different contexts

Explanation

A term is empty when its extension is null, as with 'unicorn' or 'present King of France'. Such terms can still occur meaningfully in propositions, which is why logicians distinguish meaningfulness from having a referent. Multiple meanings concern ambiguity, not emptiness.

Question 41Basic Concepts of Logic: Terms, Propositions and Arguments

Consider the argument: 'If the witness is honest, the accused is innocent. The accused is innocent. Therefore the witness is honest.' Which defect does it exhibit?

  1. It denies the antecedent
  2. It affirms the consequent Correct answer.
  3. It affirms the antecedent
  4. It commits no defect and is valid

Explanation

The second premise affirms the consequent of the conditional, and the conclusion then affirms the antecedent, which is the fallacy of affirming the consequent. Innocence could arise from other causes, so the conditional does not run backwards. Affirming the antecedent would instead move from the antecedent to the consequent.

Question 42Basic Concepts of Logic: Terms, Propositions and Arguments

Two propositions are contradictories when which relation holds between them?

  1. They can both be false but cannot both be true
  2. They can both be true but cannot both be false
  3. They cannot both be true and cannot both be false Correct answer.
  4. They always have the same truth value

Explanation

Contradictory propositions are exact opposites: one must be true and the other false, so they can be neither jointly true nor jointly false. This is the relation between an A proposition and its corresponding O proposition, and between E and I. Contrary propositions, by contrast, cannot both be true but can both be false.

Question 43Basic Concepts of Logic: Terms, Propositions and Arguments

'The morning star' and 'the evening star' both refer to Venus. What does this show about the terms involved?

  1. Both terms are empty because they describe appearances
  2. The two terms have the same sense but different reference
  3. The two terms have different senses but the same reference Correct answer.
  4. The terms are synonymous in meaning

Explanation

The phrases differ in cognitive significance, since one identifies Venus as seen at dawn and the other as seen at dusk, yet both pick out the same planet. This illustrates the distinction between sense (the way an object is presented) and reference (the object itself). Synonymy would require sameness of sense as well.

Question 44Basic Concepts of Logic: Terms, Propositions and Arguments

A categorical proposition is in 'standard form' when which conditions are met?

  1. It contains a proper name as its subject and an adjective as its predicate
  2. It has a quantifier, a subject term, a copula and a predicate term in the order A/E/I/O prescribes Correct answer.
  3. It contains at least one negation somewhere in the sentence
  4. It is written as a conditional statement with two clauses

Explanation

Standard form requires an explicit quantifier ('all', 'no', 'some'), a subject term, the copula 'is/are' and a predicate term, arranged so the proposition's quantity and quality are visible. This makes translation into A, E, I or O notation straightforward. Conditionals and singular names fall outside this categorical pattern.

Question 45Categorical Propositions and Immediate Inference

In traditional logic, a categorical proposition is a statement that relates which two elements?

  1. A hypothesis and an observation
  2. A subject term and a predicate term Correct answer.
  3. A word and its definition
  4. A premise and a conclusion

Explanation

A categorical proposition asserts a relation of inclusion or exclusion between a subject term and a predicate term, as in 'All poets are dreamers'. The other items belong to different parts of logic or language study and are not the components of a categorical proposition.

Question 46Categorical Propositions and Immediate Inference

Which pair of words correctly gives the quantity and quality of the proposition 'No politicians are honest'?

  1. Universal, affirmative
  2. Particular, affirmative
  3. Universal, negative Correct answer.
  4. Particular, negative

Explanation

Quantity is decided by whether the subject is taken in its whole extent ('No' signals universal) and quality by whether the copula affirms or denies ('are not' signals negative). The proposition is therefore universal and negative, the standard E form.

Question 47Categorical Propositions and Immediate Inference

Which proposition is an I proposition?

  1. No students are athletes.
  2. Some students are not athletes.
  3. All students are athletes.
  4. Some students are athletes. Correct answer.

Explanation

An I proposition is particular and affirmative, so it asserts that some members of the subject class fall inside the predicate class. Only 'Some students are athletes' has both a particular quantity and an affirmative copula.

Question 48Categorical Propositions and Immediate Inference

What is the contradictory of the proposition 'All metals are conductors'?

  1. Some metals are not conductors. Correct answer.
  2. All non-metals are conductors.
  3. Some metals are conductors.
  4. No metals are conductors.

Explanation

The contradictory of an A proposition is the O proposition with the same terms, since the two can never share a truth value. Reversing quantity and quality gives 'Some metals are not conductors'.

Question 49Categorical Propositions and Immediate Inference

Which proposition is the converse of 'No reptiles are warm-blooded animals'?

  1. All reptiles are warm-blooded animals.
  2. Some reptiles are not warm-blooded animals.
  3. Some warm-blooded animals are not reptiles.
  4. No warm-blooded animals are reptiles. Correct answer.

Explanation

Conversion simply exchanges subject and predicate while keeping quantity and quality, and an E proposition converts purely. The converse of 'No S is P' is therefore 'No P is S'.

Question 50Categorical Propositions and Immediate Inference

How is the obverse of 'All birds are animals' correctly formed?

  1. No non-birds are animals.
  2. All non-animals are birds.
  3. No birds are non-animals. Correct answer.
  4. Some birds are non-animals.

Explanation

Obversion changes the quality and replaces the predicate with its complement, leaving the subject and quantity untouched. The A proposition 'All S is P' thus becomes the E proposition 'No S is non-P'.