Class 11 Logic And Philosophy Unit-4 Symbolic Logic MCQs and Notes | HS 1st Year

Class 11 Logic And Philosophy Unit-4 Symbolic Logic MCQs and Notes | HS 1st Year

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Assam Board Class 11 Logic and Philosophy – Unit 4: Symbolic Logic MCQs and Complete Solution 

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Class 11 Logic And Philosophy Unit-4 Symbolic Logic MCQs and Notes | HS 1st Year

Unit-4: Symbolic Logic

Marks: 15

The short and long questions from this chapter given in the last 10 years are:

  1. If 'P' is true and 'q' is false, what will be the truth value of 'p ∨ q'?
    (1 mark, 2011)

  2. Under what condition does an equivalent function become true?

  3. What do you mean by a truth function?
    (1 mark, 2011)
    (2 marks, 2011, 2013, 2014, 2017)

  4. What are the three characteristics of Symbolic Logic according to C.I. Lewis?

  5. Construct a truth table for the following:
    (4 marks, 2011, 2012, 2015)
    (a) (p ⋅ q) ⋅ (p ∨ q)
    (5 marks, 2011)

  6. Explain the advantages of the use of symbols in Symbolic Logic.
    (5 marks, 2011)

  7. State two points of difference between Traditional and Symbolic Logic.

  8. Reduce the following sentences into logical form:
    (2 marks, 2012)
    (4 marks, 2012)
    (a) All good writers are not good speakers.
    (b) Most of the people are not honest.

  9. What do you mean by a truth function? Construct one truth table from the basic truth function.

  10. Is symbolic logic formal in nature?

  11. What is a symbol?
    (5 marks, 2012, 2015, 2016)
    (1 mark, 2013)

  12. Write short notes on 'Ideogram'.
    (2 marks, 2013)
    (4 marks, 2013)

  13. What is symbolic logic? Discuss its main characteristics.
    (5 marks, 2013)

  14. Explain briefly the importance of using symbols.
    (3 marks, 2014)

  15. State any one characteristic of symbolic logic as laid down by C.I. Lewis.
    (1 mark, 2015)

  16. State two utilities of using symbols in modern logic.

  17. State two utilities of using symbols in logic.
    (2 marks, 2015)
    (a) p > (p ⋅ q)
    (2 marks, 2015, 2017)

  18. Construct truth tables for any two of the following propositional forms to characterize each as tautologous, contradictory, or contingent.
    (4 × 2 = 8 marks, 2015)
    (a) (p ⋅ q) > (p ∨ q)
    (b) (r ⋅ p ⋅ q) ⋅ (p ~ q)

  19. If p is true and q is false, what will be the value of p > q?
    (1 mark, 2016)

  20. Construct truth tables for any two of the following statements and determine if they are tautologous, contradictory, or contingent.
    (4 marks, 2016)
    (a) ~p > q
    (b) p ∨ (q ∨ ~q)
    (c) (p ⋅ q) > (q ⋅ p)
    (d) (p ⋅ q) ⋅ (p ⋅ ~q)

  21. Write a short note on:
    (4 marks, 2016)
    (i) Variables

  22. Write a short note on 'Logical Constant'.
    (4 marks, 2016, 2018)

  23. What is Symbolic Logic? Briefly explain four characteristics of symbolic logic.
    (2 + 4 = 6 marks, 2016)

  24. Under what condition does a disjunctive function become false?
    (1 mark, 2017)

  25. Construct a truth table for any one of the following statements and determine if it is tautologous, contradictory, or contingent.
    (4 marks, 2017)
    (a) (p ∨ p) > p
    (b) (p ⋅ p) ⋅ (~p ⋅ ~q)
    (c) {~(p ⋅ q) ⋅ q}
    (d) ~p ∨ q

  26. Write a short note on the use of variables.

  27. Symbolize the following propositions:
    (4 marks, 2017)
    (a) It is not that Smita is not good.
    (b) Either Karl Popper is a logician or he is a philosopher.
    (c) If you study hard, you will pass the examination.

  28. What is Symbolic Logic? Discuss its nature.
    (6 marks, 2017)

  29. What are the basic truth functions? Construct a truth table for negative and equivalent truth functions.
    (2 + 4 = 6 marks, 2017)

  30. Under what condition does a conjunctive function become true?
    (1 mark, 2012)

  31. Is symbolic logic a developed form of classical logic?
    (1 mark, 2011)

  32. What is symbolic logic? What are the three general characteristics of symbolic logic according to C.I. Lewis?

  33. Write a short note on truth function.
    (4 marks, 2018)
    (4 marks, 2017)

MCQs

1. Who formulated classical deductive logic, which is the foundation of symbolic logic?

(i) Plato.

(ii) Aristotle.

(iii) None of the above.

(iv) All of the above.

Ans: (ii) Aristotle.

2. Which field has strongly influenced the development of symbolic logic?

(i) Biology.

(ii) Physics.

(iii) Mathematics.

(iv) Drawing.

Ans: (iii) Mathematics.

3. Which of the following terms is NOT associated with symbolic logic?

(i) Truth tables.

(ii) Ideograms.

(iii) Verbal reasoning.

(iv) All of the Above. 

Ans: (iii) Verbal reasoning.

4. Which of the following symbols is an example of an ideogram used in symbolic logic?

(i) ‘x’ (as a variable).

(ii) ‘∑’ (Summation symbol).

(iii) ‘&&’ (Logical AND operator).

(iv) ‘+’ (Addition symbol).

Ans: (iv) ‘+’ (Addition symbol).

5. What do ideograms in symbolic logic represent?

(i) Complex logical arguments.

(ii) Ideas or concepts directly.

(iii) None of the above.

(iv) All of the above.

Ans: (ii) Ideas or concepts directly.

6. What is a “valid” deductive argument?

(i) One where the conclusion logically follows from the premises.

(ii) One where the conclusion does not logically follow from the premises.

(iii) One that uses inductive reasoning.

(iv) One based on emotional reasoning.

Ans: (i) One where the conclusion logically follows from the premises.

7. What is the primary function of symbols in symbolic logic?

(i) To express complex ideas in simple language.

(ii) To represent specific logical concepts.

(iii) To describe natural phenomena.

(iv) To simplify verbal reasoning.

Ans: (ii) To represent specific logical concepts.

8. What is the primary purpose of symbols in symbolic logic?

(i) To make arguments more complex.

(ii) To express peculiar logical concepts.

(iii) To add emotional context to arguments.

(iv) To simplify natural language.

Ans: (ii) To express peculiar logical concepts.

9. What is the primary purpose of symbols in symbolic logic?

(i) To clarify the structure of logical arguments.

(ii) To express abstract mathematical ideas.

(iii) To make logical statements more concise.

(iv) Helps us to bring out the features of logical importance in arguments.

Ans: (iv) Helps us to bring out the features of logical importance in arguments.

10. What is one of the defects of ordinary language that symbolic logic aims to address?

(i) Precision.

(ii) Ambiguity.

(iii) Clarity.

(iv) Misleading.

Ans: (ii) Ambiguity.

11. What does the use of symbols in symbolic logic help the mind focus on?

(i) The material truth of the propositions.

(ii) The meaning of the words.

(iii) The form of the argument.

(iv) The influence of emotions.

Ans: (iii) The form of the argument.

12. Which of the following is a logical constant used in propositional logic?

(i) “+”

(ii) “x”

(iii) “¬” (Negation sign).

(iv) “=”

Ans: (iii) “¬” (Negation sign).

13. In propositional logic, what does a propositional formula represent?

(i) A single statement.

(ii) A logical argument.

(iii) A combination of symbols according to logical rules.

(iv) None of the above.

Ans: (iii) A combination of symbols according to logical rules.

14. What does the “∨” symbol represent in propositional logic?

(i) Conjunction (and).

(ii) Disjunction (or).

(iii) Negation (not).

(iv) Implication (if-then).

Ans: (ii) Disjunction (or).

15. Which of the following is the symbol for negation (not)?

(i) ∧

(ii) ∨

(iii) ¬

(iv) →

Ans: (iii) ¬

Questions and Answers(1 Mark)

Q1. If 'P' is true and 'Q' is false, what will be the truth value of 'P ∨ Q'?
Ans. True. (1 mark, 2011) ✅

Q2. Under what condition does an equivalent function become true?
Ans. If both variables take the same value. (1 mark, 2011) ✅

Q3. Is symbolic logic formal in nature?
Ans. Yes. (1 mark, 2013) ✅

Q4. State any one characteristic of symbolic logic as laid down by C.I. Lewis.
Ans. Use of the deduction method. (1 mark, 2015) ✅

Q5. If 'P' is true and 'Q' is false, what will be the value of 'P → Q'?
Ans. False. (1 mark, 2016) ✅

Q6. Under what condition does a disjunctive function become false?
Ans. If both disjuncts are false. (1 mark, 2017) ✅

Q7. Under what condition does a conjunctive function become true?
Ans. If both of its conjuncts are true. (1 mark, 2012) ✅

Q8. Is symbolic logic a developed form of classical logic?
Ans. Yes. (1 mark, 2011) ✅

Q9. State one utility of using symbols in logic.
Ans. The use of symbols gives clarity to complicated logical expressions. (1 mark, 2018) ✅

Q10. Symbolic logic is wholly formal—Is it true?
Ans. True. (1 mark) 

Q11. What does "ideogram" mean?
Ans. It means idea. (1 mark) 

Q12. Symbolic logic, like mathematics, is wholly deductive and formal—Is this statement true?
Ans. True. (1 mark) 

Q13. What is the main difference between classical and modern logic?
Ans. The development of different stages. (1 mark) 

Q14. On what ground does the validity of an argument depend?
Ans. The forms of an argument. (1 mark) 

Q15. Symbolic logic is based on implication or inferential relation because it is wholly deductive—Is it true?
Ans. True. (1 mark) 

Q16. Symbolic logic is a development of traditional logic.
Ans. True. (1 mark) 

Q17. Mention the name of the method which is used in symbolic logic.
Ans. Deductive method. (1 mark) 

Q18. "The development of symbolic logic is related to the development of mathematics"—Is it correct?
Ans. Yes, it is correct. (1 mark) 

Q19. The use of symbols in logic develops intellectual ability—Is it true?
Ans. True. (1 mark) 

Q21. What does "phonogram" mean?
Ans. Phonogram means sound or word.

Q22. The characteristics of mathematics are also the characteristics of modern logic—Is it true?
Ans. True. (1 mark) ✅

Q23. Is implication a formal relation?
Ans. Yes. (1 mark) ✅

Q24. Are signs variable?
Ans. Yes. (1 mark) ✅

Q25. Who wrote the book Principia Mathematica?
Ans. George Boole. (1 mark) ✅

Q26. Who wrote Dissertatio De Arte Combinatoria, a contribution to modern logic?
Ans. Leibniz. (1 mark) ✅

Q27. Who suggested a universal calculus of reasoning in modern logic?
Ans. Leibniz. (1 mark) ✅

Q28. Mention a difference between traditional logic and symbolic logic.
Ans. Symbols are used more in symbolic logic than in traditional logic. (1 mark) ✅

Q29. On what does the validity of an argument depend?
Ans. The formal construction of its constituents. (1 mark) ✅

Q30. Ideograms stand directly for what?
Ans. Concept. (1 mark) ✅

Q31. Under what condition will a disjunctive truth function be false?
Ans. If both disjuncts are false. (1 mark) ✅

Q32. Under what condition does an equivalent truth function become true?
Ans. Both constituents should be either true or false. (1 mark) ✅

Q33. What is the symbol of negation?
Ans. (or "∼" in some notations). (1 mark) ✅

Questions and Answers (Mark: 2)

Q1. What do you mean by a truth function? (2 marks, 2011, 2013, 2014, 2017) ✅
Ans. A truth function is a compound expression that contains variables, and its truth value is determined by the truth values of its constituents.

Q2. State two utilities of using symbols in logic. (2 marks, 2017) ✅
Ans.

  1. The use of symbols helps express the generality of logical rules.

  2. The use of symbols provides clarity in complex logical arguments.

Q3. What is a symbol?
Ans. The verbal or written signs used deliberately to signify something are known as symbols.

Q4. State two points of difference between traditional and symbolic logic. (2 marks, 2012, 2013) ✅
Ans.

  1. Traditional logic has a long history, whereas symbolic logic has a short history of about 150 years.

  2. The method of classical logic is both deductive and inductive, whereas symbolic logic uses only the deductive method.

Q5. Write a short note on 'Logical Constant.' (2 marks, 2016) ✅
Ans.

  1. Logical constant: A symbol that stands for a definite and specific thing, an attribute, etc.

  2. It has a well-determined meaning, which remains unchanged throughout a discourse.

Q6. Explain briefly the importance of using symbols. (2 marks, 2016) ✅
Ans.

  1. The use of symbols helps to express the generality of logical rules.

  2. The use of symbols provides clarity in complex logical arguments.

Q7. What is symbolic logic?
Ans. The branch of logic that uses a large number of symbols to express arguments and determine their truth value is called symbolic logic.

Q8. Define the deductive method. (2 marks) ✅
Ans. The deductive method is a process of deriving an indefinite number of statements from a definite number of given statements by applying a limited number of rules.

Q9. What do you mean by ideograms? (2 marks) ✅
Ans. Ideograms are symbols that directly represent an idea and indirectly represent a sound or word.

Q10. What do you mean by phonograms? (2 marks) ✅
Ans. Phonograms are signs or symbols that directly represent a sound or word and indirectly represent an idea.

Q11. Define argument. (2 marks) ✅
Ans. An argument is an inference that consists of propositions, where a conclusion is drawn from one or more premises.

Q12. Write the names of four supporters of modern logic. (2 marks, 2018) ✅
Ans. Leibniz, Whitehead, George Boole, De Morgan, and Frege.

Q13. Give two examples of ideograms. (2 marks) ✅
Ans. '+', '×', '÷', etc.

14. Give two examples of phonograms.
(1 mark)
Ans. A phonogram is a symbol representing a sound. Examples include:

  1. The letter "A" representing the /a/ sound.

  2. The letter combination "sh" representing the /ʃ/ sound.

15. What do you mean by a conjunctive constant?
(2 marks)
Ans. A conjunctive constant is a logical operator that joins two simple statements using the word "and" or the symbol "∧" (or "•" in some notations). It signifies that both statements must be true for the compound statement to be true. Example: p ∧ q (read as "p and q").

16. What do you mean by a disjunctive constant?
(2 marks)
Ans. A disjunctive constant is a logical operator that connects two simple statements using "either-or" or the symbol "∨". It signifies that at least one of the statements must be true. Example: p ∨ q (read as "p or q").

17. Define a logical constant.
(2 marks)
Ans. A logical constant is a symbol that has a fixed meaning in logical expressions and does not change throughout a discourse. Examples include logical operators such as "∧" (and), "∨" (or), "→" (implies), and "¬" (not).

18. What is a conjunctive truth function?
(2 marks)
Ans. A conjunctive truth function is a truth-functional expression where two statements are joined by a conjunctive operator ("and" or "∧"). The compound statement is true only when both individual statements are true. Example: If p = "It is raining" and q = "It is cold", then p ∧ q means "It is raining and it is cold."

19. What do you mean by a negative truth function?
(2 marks)
Ans. A negative truth function is a logical expression that includes negation ("not" or "¬") to reverse the truth value of a statement. Example: If p = "It is raining", then ¬p means "It is not raining."

20. Give the definition of a symbol.
(2 marks)
Ans. In logic, a symbol is a character or sign used to represent a logical operation, relation, or variable. Symbols replace words for clarity and precision in logical expressions. Examples: "∧" for conjunction (and), "∨" for disjunction (or), "→" for implication (if... then).

21. Define an argument.
(2 marks)
Ans. An argument is a set of statements where one or more statements (premises) provide support for a conclusion. Example:

  1. All men are mortal. (Premise)

  2. Aristotle is a man. (Premise)
    ∴ Aristotle is mortal. (Conclusion)

22. What is a truth function?
(2 marks)
Ans. A truth function is a function where the truth value of a compound statement depends on the truth values of its components. Examples: p ∧ q (conjunction), p ∨ q (disjunction), ¬p (negation).

23. Define a variable.
(2 marks)
Ans. A variable is a symbol that represents an unspecified proposition or value whose truth value may change. Example: In logical expressions, p and q are variables that can take the values "true" or "false."

Question and Answers: Marks: 3

  1. Explain briefly the importance of using symbols.  (2 mark, 2014) ✔️

    Ans.
    (1) The use of symbols helps to express the generality of logical rules.
    (2) The use of symbols gives clarity to complicated logical arguments.
    (3) The use of symbols exhibits the logical form of the argument and thereby helps to classify the argument according to its form.

  2. What is a variable? Give an example.

    Ans. The symbols which do not have any fixed reference, rather their reference can vary and may be replaced in various contexts, are called variables.

    Examples: p, q, r

  3. What is a symbol? Give an example of it.
    Ans. A sign that is a special ideographic notation used to express a thing or a peculiar logical concept is called a symbol.
    For example: p, v, r, etc.

  4. What is a logical constant? Give an example.
    Ans. A symbol that stands for a definite and specific thing, an attribute, etc., and has a well-determined meaning is called a logical constant.

  1. What is an ideogram? Give an example. (2+1=3 Mark)
    Ans. A type of symbol that stands directly for concepts or ideas and indirectly for sounds is called an ideogram.
    For example: '+', '-', '?' etc.

  2. How many kinds of logic are there? Mention two basic logical constants.
    (1+2=3 Mark)
    Ans. There are five kinds of basic logical constants.
    Two basic logical constants are:
    (1) Negative constant: '¬'
    (2) Implicative constant: '→'

  3. How many kinds of basic truth functions are there in symbolic logic? Mention two of them.  (1+2=3 Mark)
    Ans. There are five basic kinds of truth functions.
    Two basic truth functions are:
    (1) Conjunctive truth function: 'p ∧ q'
    (2) Disjunctive truth function: 'p ∨ q'

  4. What is a truth function? Give a truth table for it. (3 Mark)
    Ans. A truth function is a compound expression that contains a variable or variables, and whose truth value is determined based on its component variables.
    For example: 'p ∧ q' is a truth function.
    Truth Table:

  1. Mention the truth table of the conjunctive truth function.
    Ans. The truth table for the conjunctive truth function ('p ∧ q') is the same as given above.

Questions and Answers: Marks: 4

1. Write a short note on 'Truth Function'. (4 mark, 2018) ✔️

Ans. A truth function is a compound expression that contains a variable or variables, and whose truth value is determined based on the truth value of its component variables.

Example: 'p ∧ q' is a truth function whose value depends on the values of 'p' and 'q'.

According to logicians, there are five basic kinds of truth functions:
(i) Conjunctive truth function
(ii) Disjunctive truth function
(iii) Implicative truth function
(iv) Equivalent truth function
(v) Negative truth function

2. Reduce the following sentence into logical form. (4 mark)

Sentence: All good writers are not good speakers.

Logical Form: Some good writers are not good speakers.

Ans. This is an 'O' proposition in categorical logic.

Example:

  • Most people are honest.Some people are not honest. ('O' proposition)

3. What are the three characteristics of symbolic logic according to C.I. Lewis? (4 mark, 2012, 2014, 2015, 2014) ✔️

Ans. The three characteristics of symbolic logic, as stated by C.I. Lewis, are:

  1. The Application of Ideograms:

    • It is the first characteristic of symbolic logic.

  2. Use of Formal Systems:

    • Symbolic logic is expressed through a well-defined formal system.

  3. Precision and Clarity:

    • The use of symbols eliminates ambiguity and ensures accuracy in logical reasoning.

4. Construct truth tables for any two of the following proposition forms to characterize each of them as tautologous, contradictory, or contingent. (4×2=8 mark, 2015) ✔️

(a) Truth Table:

Since the final column contains all false (F) values, this is a contradictory proposition.

(b)Truth Table:

Since the final column contains all true (T) values, this is a tautologous proposition.

C. Truth Table:

Since the final column contains all false (F) values, this is a contradictory proposition.

5. Construct truth tables for any two of the following statements and determine whether they are tautologous, contradictory, or contingent. (4 marks, 2016) ✔️

6. Construct a truth table for any one of the following statements and determine whether it is tautologous, contradictory, or contingent. (4 marks, 2016) ✔️

7. Symbolize the following propositions.

(4 marks, 2016) ✔️

(a) "It is not that Smita is not good."

Ans. Let P = "Smita is good."
"Not" is represented by (negation).

Symbolized form:

Since double negation cancels out, this simplifies to (Smita is good).

(b) "Either Karl Popper is a logician or he is a philosopher."

Ans.

Let L = "Karl Popper is a logician."
Let P = "Karl Popper is a philosopher."
"Either...or" is represented by the disjunction (∨).

(b) "Either Karl Popper is a logician or he is a philosopher."

Ans.
Here:

  • Either - or =

  • Karl Popper is a logician = P

  • Karl Popper is a philosopher = Q

We can symbolize it using variables and constants as: P ∨ Q

(c) "If you read hard, you will pass the examination."

Ans.
Here:

  • If - then =

  • You read hard = P

  • You will pass the examination = Q

We can symbolize it using variables and constants as: P → Q

8. Write a short note on 'Logical Constant'. (4 Marks, 2016, 2018) ✔️

Ans.

  1. A constant is a symbol that stands for a definite and specific thing.

  2. Logical constants are symbols that express the form of a compound expression and maintain the same meaning throughout every occurrence in a proposition.

  3. In propositional logic, there are five kinds of logical constants.

  4. The five basic logical constants are: '∼', '∨', '∧', '→', '≡'.

9. Write a short note on 'Variables'. (4 Marks, 2016, 2017) ✔️

Ans.

  1. A variable is a symbol that can stand for any one of a given range of values.

  2. Variables are referred to as lowercase letters.

    • Example: p, q, r, s, t, etc.

  3. Variables can assume any meaning within a definite range.

  4. Through the use of variables, logicians try to symbolize statements.

10. Write a short note on 'Ideogram'. (4 Marks, 2013) ✔️

Ans.

  1. Ideograms are signs that stand directly for concepts or ideas instead of sounds.

  2. Not all dictionary-written words are ideograms.

  3. Ideograms include symbols such as 'x', '?', '+'.

11. What is symbolic logic? What are the three general characteristics of symbolic logic according to C.I. Lewis? (4 Marks, 2018) ✔️

Ans.
Using symbols in logic is known as symbolic logic. Symbolic logic is a development of concepts and techniques of traditional logic.

Three general characteristics of logic according to C.I. Lewis:

  1. The application of ideograms – A type of symbolic representation that stands directly for concepts.

  2. The application of the deductive method – A formal procedure involving the use of logical rules.

  3. The application of variables – Symbols that can stand for any one of a given range of values, with truth values varying in different uses.

1. Construct a truth table for the following:

(5 Marks, 2011) ✔️

2. Construct a truth table for the following: (5 Marks, 2011) ✔️

3. Explain the advantages of using symbols in symbolic logic.

(5 Marks, 2012, 2014) ✔️

Ans.

  1. The use of symbols exhibits the logical form of an argument and helps classify the argument according to its form.

  2. Symbols help express the generality of logical rules.

  3. The use of symbols gives clarity, conciseness, and economy of expression to complicated logical statements and arguments.

  4. Symbols help conveniently express concepts and technical terms.

  5. Using symbols in logic allows us to determine truth, falsity, validity, and invalidity in a short time.

4. What do you mean by truth function? Construct one truth table from the basic truth functions.

(5 Marks, 2016, 2015, 2012) ✔️

Ans.
A truth function is a compound expression that contains one or more variables, and its truth value is determined based on the truth values of its components.

One basic truth function is the Disjunctive Truth Function ():

5. What is symbolic logic? Discuss its main characteristics.

Ans.

  1. Symbolic logic is a modern form of classical deductive logic developed from Aristotle's traditional logic.

  2. It is an advanced form of logic that uses a large number of symbols to express arguments and determine their truth value.

Characteristics of Symbolic Logic:

  1. It uses symbols instead of ordinary language to avoid ambiguity.

  2. It focuses on the structure of arguments rather than their content.

  3. It applies precise formal rules for reasoning.

  4. It includes variables and constants to generalize logical expressions.

  5. It allows for mechanical verification of logical statements using truth tables and formal proofs.

6. How many kinds of basic truth functions are there in symbolic logic? Mention them.

(5 Marks) ✔️

Ans.
There are five basic kinds of truth functions in symbolic logic:

  1. Conjunctive truth function

  2. Disjunctive truth function

  3. Implicative truth function

  4. Equivalent truth function

  5. Negative truth function

7. How many logical constants are there in symbolic logic? Mention them. (5 Marks) ✔️

Ans.
There are five basic logical constants in symbolic logic:

  1. Negative constant (not) →

  2. Conjunctive constant (and) → (Dot)

  3. Disjunctive constant (either-or) →

  4. Implicative constant (if-then) →

  5. Equivalent constant (if and only if) →

8. What are the basic truth functions? Construct truth tables for the negative and equivalent truth functions. (2+4=6 Marks, 2017) ✔️

Ans.
A truth function is a compound expression that contains variables, and its truth value is determined solely based on the truth values of its component variables.

There are five basic truth functions:

  1. Conjunctive ()

  2. Disjunctive ()

  3. Implicative ()

  4. Equivalent ()

  5. Negative ()

9. What is symbolic logic? Discuss its nature. (6 Marks, 2017) ✔️

Ans.
Symbolic logic is a modern, developed form of classical deductive logic, originally formulated by Aristotle. It uses symbols to express logical arguments and determine their validity.

Nature of Logic:

  1. Logic deals with mediate knowledge – It is concerned with reasoning processes rather than direct experience.

  2. Logic is related to both formal and material truth – It focuses on the structure of arguments as well as their content.

  3. Logic is both a science and an art – It systematically studies reasoning while also requiring skill in application.

  4. Logic is the science of sciences and the art of arts – It provides a foundation for all rational inquiry.

  5. Logic is a normative science, not a positive science – It prescribes how we should reason correctly rather than describing how people actually reason.

10. What is symbolic logic? Briefly explain four characteristics of symbolic logic. (2+4=6 Marks, 2016) ✔️

Ans.
Using symbols in logic is known as symbolic logic. It is a modern development of concepts and techniques from traditional logic that makes reasoning more precise and systematic.

Characteristics of Symbolic Logic:

  1. Use of ideograms – Symbolic logic uses special signs (e.g., ‘x’, ‘?’, ‘+’) that stand directly for concepts instead of words.

  2. Application of the deductive method – From a small number of statements, symbolic logic generates an infinite number of conclusions using formal rules.

  3. Use of variables – Symbols like represent statements, while logical operators (e.g., ) express relationships between them.

  4. Increased use of symbols – The reliance on symbols helps determine the validity of arguments and the truth or falsity of propositions systematically.

11. Construct truth table of the following propositional form and determine whether it is tautologous, constradictory or contingent :.

(a) p> (pvq) (b) (pvq). (~p.~q)

(c) (p. q)>p (d) (p>q)vp

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