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Karnataka II PUC Logic (KSEAB) study materials
Karnataka II PUC Logic (KSEAB) study resources

Karnataka II PUC Logic (KSEAB) practice questions

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Question 1Nature and Scope of Logic

In the traditional classification of the sciences, which term does the II PUC syllabus use for the study of the correct rules of reasoning, distinguished from the actual reasoning people happen to perform?

  1. Descriptive science
  2. Natural science
  3. Normative science Correct answer.
  4. Applied mathematics

Explanation

Logic is called a normative science because it prescribes the norms or standards that correct thinking ought to follow, rather than merely describing how people in fact think. Descriptive sciences such as psychology report actual mental processes; logic evaluates them. This distinction between the 'ought' of logic and the 'is' of psychology is a standard opening theme of the Karnataka II PUC course.

Question 2Nature and Scope of Logic

The word 'logic' is derived from the Greek 'logos'. In the II PUC account, which meaning of 'logos' best explains why logic is concerned with reasoning?

  1. Motion and change
  2. Number and measure
  3. Word, reason or principle Correct answer.
  4. Pleasure and emotion

Explanation

'Logos' carries the senses of word, discourse, reason and principle, and it is from this root that 'logic' is named. Because the root points to reason and ordered discourse, logic is defined as the science of the principles of valid reasoning. The other options name Greek ideas from other fields and do not explain the etymology of 'logic'.

Question 3Nature and Scope of Logic

A student says: 'Logic tells us what people usually think.' Which criticism of this statement follows from the nature of logic as a normative science?

  1. Logic is purely descriptive, so the statement is correct as it stands
  2. Logic prescribes how we ought to reason, so it is not a report of usual thinking Correct answer.
  3. Logic concerns only mathematics, so usual thinking does not arise
  4. Logic studies only the brain, so usual thinking is irrelevant

Explanation

As a normative science, logic lays down the standards that sound reasoning must satisfy; it does not record statistical habits of thought. That people usually reason in a certain way is a psychological fact and may even be a fallacy. Hence the statement confuses the norm with the description, and the criticism in the first option is the correct one.

Question 4Nature and Scope of Logic

Which pair correctly states the relation between logic and psychology as presented in the II PUC syllabus?

  1. Both study only actual mental processes
  2. Logic studies the norms of valid thinking; psychology studies actual mental processes Correct answer.
  3. Logic studies actual mental processes; psychology studies the norms of valid thinking
  4. Both study only the norms of valid thinking

Explanation

Logic is normative and asks what makes an inference correct, while psychology is a descriptive science of how the mind actually works. The two are related because thinking is their common subject matter, but they differ in aim and method. Only the first option keeps each discipline on its proper side of that division.

Question 5Nature and Scope of Logic

Which statement best captures why logic is described as the 'science of sciences' in the traditional syllabus?

  1. Logic is taught in every science course
  2. Logic replaces the special sciences by answering their factual questions
  3. Logic is the oldest of the sciences and therefore ranks first
  4. Every science uses reasoning, so the rules of valid inference apply within all of them Correct answer.

Explanation

The title 'science of sciences' is given because all inquiry, including scientific inquiry, proceeds by inference, and logic supplies the principles that make inference sound. It is thus a tool or organon used by other disciplines rather than a rival to them. The other options confuse methodological importance with factual content or mere seniority.

Question 6Nature and Scope of Logic

Which of the following is a definition of logic that matches the II PUC syllabus?

  1. The study of the structure of the brain
  2. The art of winning arguments by any means
  3. The collection of true statements about the world
  4. The science of the principles of valid reasoning Correct answer.

Explanation

Logic is defined as the science of the principles of valid reasoning, that is, of the conditions under which a conclusion follows from premises. Winning by any means is rhetoric or sophistry, and truth-collection is the task of the special sciences. The definition also marks logic as a science rather than a mere knack.

Question 7Nature and Scope of Logic

'Logic is both a science and an art.' Which explanation of this statement is correct?

  1. It is a science because it is taught in schools, and an art because it is examined
  2. It is a science because it is old, and an art because it is difficult
  3. It is a science because it is a systematic body of principles, and an art because those principles are applied in actual reasoning Correct answer.
  4. It is a science because it uses instruments, and an art because it uses imagination

Explanation

A body of knowledge is a science when it is systematically organised, and an art when its rules are applied in practice. Logic satisfies both descriptions: it states principles of validity and also guides the actual drawing of inferences. The remaining options appeal to equipment, schooling, age or difficulty, none of which is the basis of the distinction.

Question 8Nature and Scope of Logic

Logic is often called an 'organon'. What does this term indicate about the place of logic among the sciences?

  1. It is the highest of the natural sciences
  2. It is a substitute for experiment
  3. It is an instrument or tool used by all other sciences Correct answer.
  4. It is a branch of medicine

Explanation

'Organon' means instrument or tool, and logic is so called because it provides the method of valid inference that every science employs. It is not a body of facts competing with the special sciences but a general instrument for them. Hence the title stresses service and method rather than rank or subject matter.

Question 9Nature and Scope of Logic

Which statement correctly distinguishes logic from the special sciences such as physics and botany?

  1. Logic studies the form of reasoning common to all inquiry, while the special sciences study particular classes of facts Correct answer.
  2. Both logic and the special sciences study only particular facts
  3. Both logic and the special sciences study only the form of reasoning
  4. Logic studies particular facts, while the special sciences study the form of reasoning

Explanation

The special sciences have a definite subject matter, such as matter in motion or plant life, and they gather facts about it. Logic abstracts from any particular subject matter and examines the form that valid inference takes in all of them. This generality of form is what marks logic off from the special sciences.

Question 10Nature and Scope of Logic

Which of the following is a formal object of logic rather than a material object?

  1. The chemical composition of water
  2. The height of the Himalayas
  3. The number of students in a class
  4. The validity of the inference from premises to conclusion Correct answer.

Explanation

Logic does not study the subject matter of premises but the connection between premises and conclusion, that is, validity. The other items are particular facts belonging to chemistry, geography and statistics respectively. This is why logic is said to be a formal rather than a material science.

Question 11Nature and Scope of Logic

A candidate argues: 'Since every question in this paper is easy, and this is a question in this paper, it is easy.' Which feature makes the reasoning formally valid?

  1. The conclusion follows from the premises by the form of the argument, whatever the facts may be Correct answer.
  2. The argument is persuasive to the examiner
  3. The premises are in fact true
  4. The conclusion is in fact true

Explanation

Validity depends on the form of the argument: if the two premises are granted, the conclusion cannot be denied without contradiction, and this holds for any terms substituted in the same pattern. Whether the premises or conclusion are actually true is a separate question of soundness. Persuasion is a rhetorical matter and does not establish validity.

Question 12Nature and Scope of Logic

Which statement about truth and validity is correct?

  1. An argument can be valid with false premises, but it is sound only when its premises are true and its form is valid Correct answer.
  2. An argument is sound whenever its conclusion is true
  3. An argument is valid only when all its statements are true
  4. Validity and truth are the same property of arguments

Explanation

Validity is a property of the connection between premises and conclusion, so an argument may be valid even with false premises. Soundness adds the further requirement that the premises are actually true. Truth, by contrast, is a property of individual statements, not of the inference as such.

Question 13Nature and Scope of Logic

Which of these is a 'material' fallacy in the traditional classification, that is, a fallacy in which the content of the argument, rather than its form alone, is at fault?

  1. The middle term is undistributed in both premises of a syllogism
  2. The argument appeals to the emotions of the audience instead of giving evidence Correct answer.
  3. The syllogism has two negative premises
  4. The syllogism has four terms instead of three

Explanation

Material fallacies arise from the subject matter or the manner of persuasion, as when emotion is used in place of evidence. The other three are formal fallacies, since they are detected by inspecting the structure of a categorical syllogism. The distinction between material and formal fallacies is a standard part of the syllabus.

Question 14Nature and Scope of Logic

In the classification of the sciences, logic is usually grouped with which of the following?

  1. Physics and chemistry, as natural sciences
  2. Ethics and aesthetics, as normative sciences Correct answer.
  3. Geometry and arithmetic, as exact sciences of quantity
  4. History and archaeology, as historical sciences

Explanation

Logic, ethics and aesthetics are all normative, since each prescribes standards: for correct reasoning, for right conduct, and for beauty respectively. Physics and chemistry describe natural phenomena, history reconstructs past events, and geometry and arithmetic study quantity. The grouping with ethics and aesthetics therefore marks logic as normative.

Question 15Nature and Scope of Logic

Which statement about the scope of logic is correct according to the syllabus?

  1. Logic applies to reasoning in every field, but it does not by itself supply knowledge of any particular field Correct answer.
  2. Logic applies only to mathematical reasoning
  3. Logic supplies the factual content of all the sciences
  4. Logic applies only to philosophical reasoning

Explanation

Because logic studies the form of inference, its scope extends to every discipline in which conclusions are drawn from premises. It is not restricted to mathematics or philosophy, and it does not generate the factual content of any science. Its universality is precisely its lack of a special subject matter.

Question 16Nature and Scope of Logic

A student claims that because logic is normative, it cannot be used to criticise arguments in everyday life. Which reply is correct?

  1. Everyday arguments are outside logic because they are not scientific
  2. Norms are precisely what we use to criticise actual reasoning, so everyday arguments fall within logic's scope Correct answer.
  3. Everyday arguments are outside logic because they have no premises
  4. Everyday arguments are outside logic because they are not written in symbols

Explanation

A normative science supplies the standard by which actual performances are judged, as ethics judges conduct; in the same way logic judges everyday reasoning. The absence of symbols, of explicit premises, or of scientific status does not remove an argument from the scope of logical appraisal. Hence the claim confuses being normative with being inapplicable.

Question 17Nature and Scope of Logic

Which of the following best explains why logic is said to be a 'normative' rather than a 'positive' science?

  1. It lays down standards of correct reasoning instead of merely recording what people do Correct answer.
  2. It deals with positive facts of nature
  3. It is concerned only with pleasant experiences
  4. It collects data through experiments

Explanation

A positive or descriptive science records what is the case, whereas a normative science states what ought to be the case. Logic prescribes the conditions of valid inference and so is normative in this sense. The other options describe empirical or experimental sciences, which logic is not.

Question 18Nature and Scope of Logic

Which statement about the relation between logic and language is correct?

  1. Logic studies reasoning, which is expressed in language, but it is not the same as grammar or rhetoric Correct answer.
  2. Logic is identical with rhetoric
  3. Logic is identical with grammar
  4. Logic has no connection with language at all

Explanation

Reasoning is conveyed through language, so logic must pay attention to the meaning and structure of sentences. It nevertheless differs from grammar, which studies correct usage, and from rhetoric, which studies effective persuasion. Logic is thus related to language without being reducible to either grammar or rhetoric.

Question 19Nature and Scope of Logic

In the traditional scheme of the syllabus, which of the following is a 'normative science' alongside logic?

  1. Botany
  2. Ethics Correct answer.
  3. Geology
  4. Astronomy

Explanation

Ethics, like logic, prescribes a standard, namely the standard of right and wrong conduct, and so is a normative science. Astronomy, geology and botany are descriptive sciences of natural phenomena. The pairing of logic with ethics illustrates the normative category clearly.

Question 20Nature and Scope of Logic

An argument is said to be 'sound'. Which pair of conditions must it satisfy?

  1. The conclusion must be true and the premises must be long
  2. The form must be valid and all the premises must be true Correct answer.
  3. The form must be valid and the conclusion must be interesting
  4. The premises must be believed and the conclusion must be accepted

Explanation

Soundness is validity together with true premises; given both, the conclusion is guaranteed to be true as well. Interest, length, or mere belief and acceptance are psychological or stylistic features that have no bearing on soundness. This definition follows directly from the distinction between validity and truth.

Question 21Terms, Propositions and Classification

In classical logic, a term that can stand as the subject of a proposition and refers to a class of objects is called a:

  1. Syncategorematic term
  2. Modal term
  3. Categorical term Correct answer.
  4. Hypothetical term

Explanation

A categorical term is one that can serve as subject or predicate of a categorical proposition, naming a class of objects. Syncategorematic words such as 'and' or 'all' cannot stand alone as terms. Hypothetical and modal are not standard classifications of terms in this scheme.

Question 22Terms, Propositions and Classification

The term 'the present Chief Minister of Karnataka' is best classified as:

  1. An abstract term
  2. A singular term Correct answer.
  3. A collective term
  4. A general term

Explanation

A singular term denotes exactly one individual object or person. Since the description picks out a single officeholder, it functions as a singular (individual) term even though it is grammatically a phrase. General terms, by contrast, apply to each member of a class.

Question 23Terms, Propositions and Classification

'Humanity' is an example of which kind of term?

  1. Abstract term Correct answer.
  2. Collective term
  3. Concrete term
  4. Distributive term

Explanation

An abstract term names a quality, attribute or property considered apart from the things possessing it. 'Humanity' names the property of being human, not any individual human being. Concrete terms, by contrast, name things that possess such qualities.

Question 24Terms, Propositions and Classification

The word 'army' in 'The army marched past the parade ground' is used as:

  1. An abstract term
  2. A collective term Correct answer.
  3. A singular term
  4. A distributive term

Explanation

A collective term applies to a group of individuals taken as a single whole, so a predicate true of the group need not be true of each member. 'Army' here denotes the soldiers as one organised body. A distributive use would apply the predicate to each soldier separately.

Question 25Terms, Propositions and Classification

Which pair correctly states the denotation and connotation of the term 'triangle'?

  1. Denotation: all triangles; connotation: the property of having three sides Correct answer.
  2. Denotation: three-sidedness; connotation: three-sidedness
  3. Denotation: the property of having three sides; connotation: all triangles
  4. Denotation: geometrical figures; connotation: angles

Explanation

Denotation is the set of objects to which a term applies, while connotation is the set of attributes that justifies applying it. For 'triangle', the objects denoted are all triangles and the attributes connoted are having three sides. Reversing them is a common error.

Question 26Terms, Propositions and Classification

Two terms are said to be co-extensive (equivalent) when they:

  1. Have the same denotation but different connotations Correct answer.
  2. Have the same connotation but different denotations
  3. Have neither denotation nor connotation in common
  4. Differ in both denotation and connotation

Explanation

Co-extensive terms apply to exactly the same objects while conveying different attributes. Classic examples are 'equiangular triangle' and 'equilateral triangle', which denote the same figures but connote different properties. They are therefore not synonymous even though their extensions match.

Question 27Terms, Propositions and Classification

In the proposition 'Some poets are not realists', the term 'realists' is:

  1. Undistributed, because it is the predicate of a particular proposition Correct answer.
  2. Distributed, because the proposition is negative
  3. Distributed, because it is negated
  4. Undistributed, because it is the subject

Explanation

In an O proposition (particular negative), only the subject term is distributed; the predicate is undistributed. The quantity word 'some' limits the subject, and the predicate is not taken in its full extension. Distribution depends on proposition type, not on the presence of 'not' alone.

Question 28Terms, Propositions and Classification

Which proposition has both its subject and its predicate distributed?

  1. All logicians are careful thinkers
  2. No logicians are careless thinkers Correct answer.
  3. Some logicians are not careless thinkers
  4. Some logicians are careful thinkers

Explanation

In an E proposition (universal negative), both subject and predicate are distributed because the whole class denoted by each term is excluded from the other. Universal affirmatives distribute only the subject, and particular propositions distribute only the subject in the negative case.

Question 29Terms, Propositions and Classification

The proposition 'No honest officials are corrupt' belongs to which type in the traditional square of opposition?

  1. E Correct answer.
  2. O
  3. A
  4. I

Explanation

An E proposition is a universal negative, of the form 'No S are P'. The word 'No' signals universal quantity together with negative quality. A is universal affirmative, I particular affirmative, and O particular negative.

Question 30Terms, Propositions and Classification

'All that glitters is not gold' is best rendered in standard categorical form as:

  1. No glittering things are gold
  2. All glittering things are gold
  3. Some glittering things are not gold Correct answer.
  4. Some glittering things are gold

Explanation

The proverb means that not everything glittering is gold, i.e. at least one glittering thing is not gold. That is a particular negative (O) proposition. Reading it as a universal negative would wrongly claim that nothing glittering is gold.

Question 31Terms, Propositions and Classification

According to the traditional square of opposition, if 'All students are attentive' is true, what follows about 'No students are attentive'?

  1. It is true
  2. It is undetermined
  3. It is doubtful but possibly true
  4. It is false Correct answer.

Explanation

A and E propositions are contraries: they cannot both be true, though they can both be false. Since the A proposition is given as true, the E proposition must be false. This is the contrary relation on the square.

Question 32Terms, Propositions and Classification

'Some citizens are voters' and 'Some citizens are not voters' are related on the square of opposition as:

  1. Subalterns
  2. Contraries
  3. Contradictories
  4. Subcontraries Correct answer.

Explanation

I and O propositions with the same subject and predicate are subcontraries: they cannot both be false, though they can both be true. This differs from contradictories, which differ in both quantity and quality. Subalternation relates propositions of the same quality but different quantity.

Question 33Terms, Propositions and Classification

From the truth of 'All judges are impartial', which proposition can be validly inferred by subalternation?

  1. Some judges are not impartial
  2. No judges are impartial
  3. Some judges are impartial Correct answer.
  4. All impartial persons are judges

Explanation

Subalternation allows inference from a true universal to its corresponding particular of the same quality. The I proposition 'Some judges are impartial' follows from the A proposition. The inference does not run in the reverse direction.

Question 34Terms, Propositions and Classification

'If it rains, the ground gets wet' is an example of which kind of proposition?

  1. Hypothetical Correct answer.
  2. Disjunctive
  3. Categorical and disjunctive
  4. Categorical

Explanation

A hypothetical (conditional) proposition asserts that one proposition follows from another, expressed in if-then form. It does not simply affirm or deny a predicate of a subject as a categorical proposition does. Disjunctive propositions present alternatives joined by 'or'.

Question 35Terms, Propositions and Classification

'Either the accused is guilty or the accused is innocent' is classified as:

  1. A hypothetical proposition
  2. A disjunctive proposition Correct answer.
  3. A categorical proposition
  4. A conjunctive proposition

Explanation

A disjunctive proposition asserts that one of two alternatives holds, joined by 'or'. The two components are called disjuncts. Conjunctive propositions join components with 'and', and hypothetical ones use if-then.

Question 36Terms, Propositions and Classification

In 'Some metals are not magnetic', the subject term 'metals' is:

  1. Undistributed, because the proposition is negative
  2. Distributed, because it is the subject of a negative proposition Correct answer.
  3. Undistributed, because the proposition is affirmative
  4. Distributed, because the proposition is particular

Explanation

In an O proposition the subject is distributed and the predicate is undistributed. The subject is distributed because the proposition says something about part of the class, and distribution of the subject in O follows from the negative quality. Quantity and quality together determine which terms are distributed.

Question 37Terms, Propositions and Classification

Which set of terms is correctly described as synonymous?

  1. 'Teacher' and 'student'
  2. 'Bachelor' and 'unmarried man' Correct answer.
  3. 'Doctor' and 'patient'
  4. 'Triangle' and 'square'

Explanation

Synonymous terms have the same denotation and the same connotation, so they are interchangeable without change of meaning. 'Bachelor' and 'unmarried man' denote the same persons and convey the same attributes. Co-extensive terms, by contrast, share denotation but differ in connotation.

Question 38Terms, Propositions and Classification

The relation between 'equilateral triangle' and 'equiangular triangle' is best described as:

  1. Synonymous terms
  2. Unrelated terms
  3. Contradictory terms
  4. Co-extensive but non-synonymous terms Correct answer.

Explanation

The two terms denote exactly the same figures, so they are co-extensive, yet they connote different properties (equal sides versus equal angles). Co-extension therefore does not guarantee synonymy. Their equivalence in geometry is a theorem, not a definitional identity of meaning.

Question 39Terms, Propositions and Classification

A term that refers to a class with more than one member is called:

  1. A collective term
  2. A singular term
  3. An abstract term
  4. A general term Correct answer.

Explanation

A general (common) term applies to each member of a class containing more than one member, such as 'city' or 'student'. A singular term applies to exactly one object. Collective and abstract terms cut across this distinction rather than defining it.

Question 40Terms, Propositions and Classification

Which proposition is a universal affirmative in which the predicate term is undistributed?

  1. All mammals are warm-blooded animals Correct answer.
  2. Some mammals are not land animals
  3. Some mammals are aquatic animals
  4. No mammals are cold-blooded animals

Explanation

An A proposition is universal affirmative, and in it only the subject is distributed while the predicate remains undistributed. 'All mammals are warm-blooded animals' has exactly this form. In E propositions both terms are distributed, and in I and O propositions the predicate is undistributed.

Question 41Terms, Propositions and Classification

The connotation of a term is also known as its:

  1. Extension
  2. Intension Correct answer.
  3. Reference
  4. Denotation

Explanation

Connotation, or intension, is the set of attributes a term implies, while denotation, or extension, is the class of objects to which it applies. The two vary inversely in many cases. Extension and reference are synonyms for denotation, not connotation.

Question 42Terms, Propositions and Classification

Consider 'All roses are flowers' and 'Some roses are red'. Which conclusion follows validly about red flowers?

  1. Some roses are not flowers
  2. All red flowers are roses
  3. No flowers are red
  4. Some flowers are red Correct answer.

Explanation

Since some roses are red and all roses are flowers, at least one red thing is a flower, so some flowers are red. This is a straightforward chain of categorical reasoning. The other options either convert illegitimately or contradict the premises.

Question 43Terms, Propositions and Classification

In the proposition 'Some books are not novels', the word 'some' functions to indicate:

  1. Particular quantity Correct answer.
  2. Collective quantity
  3. Universal quantity
  4. Singular quantity

Explanation

'Some' is the standard indicator of particular quantity, meaning at least one but not necessarily all. In traditional logic it does not imply 'only some'. Universal quantity is signalled by words like 'all' or 'no'.

Question 44Terms, Propositions and Classification

Which statement about the distribution of terms in an I proposition is correct?

  1. Only the predicate is distributed
  2. Neither subject nor predicate is distributed Correct answer.
  3. Only the subject is distributed
  4. Both subject and predicate are distributed

Explanation

A particular affirmative proposition says that the classes denoted by subject and predicate overlap without exhausting either, so neither term is taken in its full extension. Hence neither term is distributed. Distribution of the predicate occurs only in universal negatives.

Question 45Categorical Propositions and Immediate Inference

In the traditional scheme of categorical propositions, which pair of propositions is contradictory?

  1. A and O Correct answer.
  2. A and I
  3. I and O
  4. A and E

Explanation

Contradictory propositions differ in both quantity and quality, and they can never share the same truth value. A (universal affirmative) and O (particular negative) differ in both respects, so one is true exactly when the other is false. The same holds for E and I.

Question 46Categorical Propositions and Immediate Inference

The proposition "No reptiles are warm-blooded animals" has which form and quality?

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

Explanation

A categorical proposition beginning with "No" and making a claim about the whole class is universal and negative, which is the E form. Its subject term is distributed and its predicate term is also distributed.

Question 47Categorical Propositions and Immediate Inference

In the proposition "Some students are athletes", which terms are distributed?

  1. Neither the subject nor the predicate term Correct answer.
  2. Only the subject term
  3. Only the predicate term
  4. Both the subject and the predicate term

Explanation

An I proposition is particular affirmative, and the distribution rule states that neither term in a particular affirmative proposition is distributed. "Some students" does not refer to every student, and "athletes" is not claimed in its full extent.

Question 48Categorical Propositions and Immediate Inference

Which proposition is the obverse of "All metals are conductors"?

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

Explanation

Obversion changes the quality of the proposition and replaces the predicate with its complement, leaving the subject unchanged. "All S are P" therefore becomes "No S are non-P". The truth value is preserved.

Question 49Categorical Propositions and Immediate Inference

The process of immediate inference that changes the subject and predicate terms while keeping the same quality is called

  1. obversion
  2. subalternation
  3. conversion Correct answer.
  4. contraposition

Explanation

Conversion interchanges the subject and predicate terms and keeps the quality of the original proposition unchanged. It is valid without limitation only for E and I propositions, while A and O require limitation or are invalid.

Question 50Categorical Propositions and Immediate Inference

Which proposition is the converse of "Some singers are dancers"?

  1. No dancers are singers
  2. Some singers are not dancers
  3. All dancers are singers
  4. Some dancers are singers Correct answer.

Explanation

Conversion simply interchanges subject and predicate while preserving quality and quantity. For an I proposition the simple converse is valid, giving "Some dancers are singers" with the same truth value.