Class 12 Logic & Philosophy Chapter 3 Hypothesis
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Selected Questions & Answers
A. Very Short Answer Questions: (Marks for each – 1)
1. Write the correct answer:
Hypothesis is a purposeless/purposeful assumption.
Ans: Purposeful.
2. “Hypothesis controls observation.” Is the statement true?
Ans: True.
3. ‘Hypothesis helps deduction.’ Is the statement correct?
Ans: Yes, it helps deduction.
4. “The subject-matter of a hypothesis must be an existent cause.”Is it true?
Ans: True.
5. “Hypothesis is the first stage of scientific inquiry.” Is the statementtrue?
Ans: True.
6. “Hypothesis is an imaginary assumption.” Is it true?
Ans: True.
7. According to difference in explanation, how many kinds ofhypothesis are there?
Ans: Three kinds.
8. Can an indefinite idea be a hypothesis?
Ans: Yes.
9. “A problem opens the way for the formation of a hypothesis.” Isthe statement true?
Ans: True.
10. According to Mill, what is the principal objective of induction?
Ans: Discovery.
11. What is the first means of proving a hypothesis?
Ans: Verifiability.
12. What is the first stage of hypothesis?
Ans: Observation of natural phenomena.
13. According to purposive aspect, how many kinds of hypothesisare there?
Ans: Three kinds.
14. Must a hypothesis have the power of prediction?
Ans: It must have.
15. “Hypothesis is the guide of scientific inquiry.” Is the statementtrue?
Ans: True.
16. How many experimental methods did Mill accept?
Ans: Five.
17. According to Mill, what are the fundamental methods ofinduction?
Ans: According to Mill, the fundamental methods of induction are two, namely the Method of Agreement and the Method of Difference.
18. What is the aim or objective of Mill’s inductive methods?
Ans: The discovery and proof of the causal relation among phenomena isthe aim of Mill’s inductive methods.
19. How many instances are necessary for the application of theMethod of Agreement? H. S. ’13, ’20
Ans: Two or more.
20. Is the conclusion of the Method of Agreement certain? H. S. ’19
Ans: No.
21. How many instances are required for the Method of Difference? H. S. ’12
Ans: Two.
22. Name the experimental method based on the following canon ofelimination: H. S. ’14
“If any part of the antecedent can be eliminated without any loss to theeffect, that part is not the cause of the effect nor any part of the cause.”
Ans: Method of Difference.
23. “If heat is applied to ice, it melts. If heat is not applied, ice doesnot melt. Therefore, heat is the cause of the melting of ice.”Name the experimental method used in the above argument. H. S. ’15
Ans: Method of Difference.
24. Name the experimental method which investigates thequantitative relation between cause and effect. H. S. ’18
Ans: Method of Concomitant Variations.
25. “The Joint Method and the Method of Difference are methodsof observation.” Is the statement correct? H. S. ’16
Ans: Not correct.
26. “The possibility of plurality of causes may render the Methodof Agreement ineffective.” Is the statement correct? H. S. ’15
Ans: Not correct.
27. “If a phenomenon is known to be the cause of a particular effect, it cannot be the cause of another effect.” Name the experimental method based on the above canon. H. S. ’15
Ans: Method of Residues.
28. Is prior knowledge of the effect or cause necessary for theapplication of the Method of Residues? H. S. ’18
Ans: Yes.
29. On which canon of elimination is the Method of Agreementbased? H. S. ’19
Ans: On the first canon.
30. State Mill’s definition of the Method of Residues. H. S. ’20
Ans: Mill’s definition of the Method of Residues is— “If from a phenomenon such part as is known by previous induction to bethe effect of certain antecedents is subtracted, the remainder of thephenomenon is the effect of the remaining antecedents.”
31. Write the canon of elimination on which the Method ofDifference is based. H. S. ’20
Ans: The canon on which the Method of Difference is based is—If anypart of the antecedent cannot be eliminated without loss to the effect, that part must be the cause of the effect or an essential part of the cause.
B. Short Questions and Answers (Marks for each–2)
1. What is the special feature of the Method of ConcomitantVariations?
Ans: In the Method of Concomitant Variations, the circumstances varytogether in degree rather than one being completely absent.
2. Give one example of the Method of Concomitant Variations.
Ans: One example of the Method of Concomitant Variations is—whenthe supply of a commodity increases, its price decreases. Similarly, when thesupply decreases, the price increases. Therefore, the quantity of supply is thecause of the rise and fall in price.
3. Why is the conclusion of the Method of Agreement not certain?
Ans: The Method of Agreement is mainly a method of observation; it isnot an experimental method. It merely indicates the possibility of a causal connection but cannot prove it with certainty. Therefore, the result orconclusion obtained by this method is always probable, not certain.
4. Why are inductive methods called canons of elimination? H. S. ’13, 14, 16
Ans: Inductive methods are called canons of elimination because theyeliminate accidental, unreal, or irrelevant circumstances.
5. Why is the Method of Difference called a method of proof? H. S. ’18
Ans: The Method of Difference is called a method of proof because the required instances are collected through experiment, and an attempt is madeto determine and establish the causal relation among the collected facts.
6. Mention two practical defects of the Method of Agreement. H. S. ’17
Ans: Two practical defects of the Method of Agreement are—(a) Difficulty in collecting the necessary instances.
(b) Difficulty in properly analyzing the instances.
7. Why do some logicians call the Method of Agreement the Methodof Single Agreement? H. S. ’15
Ans: In the Method of Agreement, different instances are compared, andone common circumstance found in all is taken as the basis for determiningthe causal relation. Hence it is called the Method of Single Agreement.
8. Mention one advantage of the Method of Agreement. Why is itcalled a method of discovery? H. S. ’17
Ans: One advantage of the Method of Agreement is that it is observational; therefore, its scope is wide. Since instances are collected through observationalone and the method is applied to discover causal relations, it is called amethod of discovery.
9. Give a real example of the Joint Method of Agreement andDifference. H. S. ’15
Ans: A real example of the Joint Method of Agreement and Differenceis—malaria occurs in places where Anopheles mosquitoes are present, but malaria does not occur where Anopheles mosquitoes are absent. Therefore, it may be concluded that Anopheles mosquitoes are the cause of malaria.
10. Write the second canon of elimination. Name the experimental method based on this canon. H. S. ’17
Ans: The second canon of elimination is—“If any part of the antecedent cannot be eliminated without loss to theeffect, that part must be the cause of the effect or an essential part of thecause.”
11. What is meant by a Crucial Instance? H. S. ’16, 19
Ans: An instance which not only satisfactorily explains one event amongthe events of a hypothesis but also eliminates irrelevant events is called acrucial or decisive instance.
12. Write the canon stated by Mill regarding the Method ofAgreement. H. S. ’18
Ans: The canon stated by Mill regarding the Method of Agreement is— “If two or more instances of the phenomenon under investigation have onlyone circumstance in common, the circumstance in which alone all the instancesagree is the cause (or effect) of the given phenomenon.”
C. Medium Length Questions & Answers (Marks for each–4)
1. Mention three advantages of the Method of ConcomitantVariations.
Ans: The Method of Concomitant Variations is a practical method. Itsadvantages are—
(a) It can be applied to determine causal relations in cases involvingpermanent agents such as air pressure, gravitation, heat, etc.
(b) Since it is both observational and experimental, causal relations canbe determined with certainty through this method.
(c) Besides determining causal relation, it also examines the quantitativerelation between two phenomena.
2. According to difference in the explanation of phenomena, howmany kinds of hypothesis are there and what are they?
Ans: According to difference in explanation of phenomena, hypothesis isof three kinds—
(1) Agent-relative hypothesis.
(2) Law-relative hypothesis.
(3) Hypothesis relating to circumstantial conditions.
3. Why is the Method of Agreement mainly a method of observation?
Ans: The Method of Agreement is mainly a method of observationbecause, for its application, two or more instances of the phenomenon must be collected, and among them one circumstance must be common while othersdiffer. It cannot be ensured that no other common factor is hidden beyondobservation. It only indicates a possible causal connection. Therefore, it isprimarily a method of observation, not of experiment.
4. Why did Mill describe experimental methods as methods ofelimination? H. S. ’18
Ans: Mill described experimental methods as methods of eliminationbecause—
(a) By applying experimental methods, irrelevant circumstances can beeliminated in determining causal relations.
(b) These methods depend upon the four canons of elimination. Elimination means rejection of accidental or irrelevant circumstances. Thisrejection is a negative aspect and serves as a means to achieve the mainobjective.
5. Write the canon of elimination on which the Method of Differenceis based. H. S. ’18
Ans: The canon on which the Method of Difference is based is— “If any part of the antecedent cannot be removed without loss to the effect, that part must be the cause of the effect or an essential part of the cause.”
6. Define the Method of Concomitant Variations with a real example. Why is it called a special form of the Method of Difference? H. S. ’16
Ans: If a change in one phenomenon is accompanied by a correspondingchange in another phenomenon, then the two are causally connected. In thismethod, variation in one factor is accompanied by variation in another. An example is—when the supply of a commodity increases, its pricedecreases; when supply decreases, price increases. Thus, supply is causallyrelated to price variation.
This method is called a special form of the Method of Difference becausethe determination of variation between phenomena is made through controlledcomparison, similar to the logic of difference.
7. Define the Method of Residues. Why do some logicians call itdeductive? H. S. ’18
Ans: The Method of Residues may be defined as follows—if from aphenomenon a part is known by previous induction to be the effect of certain antecedents, then the remaining part of the phenomenon is the effect of theremaining antecedents. Some logicians call this method deductive because a part of the effect isalready known beforehand, and on the basis of this prior knowledge, the causal relation is established. It does not depend exclusively on fresh observation or experiment.
8. Mention two advantages and two disadvantages of the Method ofConcomitant Variations. H. S. ’14, ’18
Ans: Two advantages of the Method of Concomitant Variations are—(a) It can be applied to permanent agents like air pressure, gravitation, heat, etc., to determine causal relations.
(b) Being observational and experimental, it helps in determining causal relations effectively. Two disadvantages are—
(a) It is not applicable to qualitative changes.
(b) It cannot be applied beyond the limits of experience.
9. Mention two advantages and two disadvantages of the JointMethod of Agreement and Difference. H. S. ’16, ’18, ’19
Ans: Two advantages of the Joint Method are—(a) Since it depends on observation, it helps in determining cause fromeffect and effect from cause.
(b) It is an improved form of the Method of Agreement. Two disadvantages are—
(a) Being an observational method, it retains the defects of observation.
(b) It is not free from the fallacy of plurality of causes.
10. Mention two advantages and two disadvantages of the Methodof Residues. H. S. ’15, ’20
Ans: Two advantages of the Method of Residues are— (a) It has been used in chemistry and astronomy to discover many newfacts.
(b) It can separate the causal components within a complex effect. Two disadvantages are—
(a) Its application is very limited.
(b) It cannot be applied at the initial stage of establishing causal relations.
D. Essay-type Questions and Answers (Marks for each–6)
1. Explain the Method of Agreement with an example.
Ans: Explaining the Method of Agreement, Mill states that if among twoor more instances in which the phenomenon under investigation is present there is only one common circumstance, and if all the instances agree only inthat one circumstance, then that circumstance is the cause or effect of thephenomenon under investigation.
According to Mill’s canon, in order to apply the Method of Agreement—First, two or more positive instances in which the phenomenon is present must be collected through observation.
Second, the collected instances must be analyzed into their different circumstances and compared with one another.
Third, the circumstances that are irregularly present must be eliminated.
Fourth, the circumstance that is regularly present in all the instances istaken as the cause or effect of the phenomenon under investigation.
Example: An electric bell is placed inside a glass jar filled with air andconnected to electricity; when the bell rings, sound is heard. Under the sameconditions, if the jar is made airless and the bell is rung, no sound is heard. Therefore, it may be concluded that the presence of air is the cause ofhearing sound.
2. Mention two advantages and two disadvantages of the Method ofAgreement. How can these disadvantages be removed? H. S. ’16, 18, 19
Ans: Two advantages of the Method of Agreement are—(a) Being observational, its field of application is very wide.
(b) With its help, we may proceed from cause to effect and from effect tocause.
(c) In scientific inquiry, it helps in the formation of hypotheses. Since the Method of Agreement is observational, it has several limitationsand inherent defects. These defects may be reduced as follows—First, the number of instances should be increased. The greater the numberof agreeing instances, the less the possibility of plurality of causes. Second, by applying the Joint Method of Agreement and Difference, thepossibility of plurality of causes can be reduced, as it is a more refined methodthan the simple Method of Agreement.
3. Explain the Method of Difference with an example.
Ans: Mill explains the Method of Difference as follows—“If an instance in which the phenomenon under investigation occurs andan instance in which it does not occur have every circumstance in common except one, that one differing circumstance, present in the former and absent in the latter, is the cause or an indispensable part of the cause of thephenomenon.” The Method of Difference is based on the second canon of elimination. Its main features are—
(a) Two instances are required—one positive and one negative.
(b) The two instances must agree in all respects except one circumstance, which constitutes the difference.
Example: The weight of a truck with goods is two tons. The weight of thegoods is one and a half tons. Therefore, the weight of the empty truck is halfa ton.
4. Mention three advantages and three disadvantages of the Method of Difference. H. S. ’15, ’18, ’19
Ans: Three advantages of the Method of Difference are—(a) There is no difficulty in collecting instances, as only two instances arerequired.
(b) Being experimental, it can conclusively establish causal relations whenproperly applied.
(c) The probable conclusion reached by the Method of Agreement can be definitively verified by the Method of Difference.
Three disadvantages are—
(a) Being experimental, its field of application is very limited.
(b) By experiment, we can proceed from cause to effect, but not fromeffect to cause.
(c) It is not entirely free from the possibility of plurality of causes.
5. Define the Method of Difference with an example. Show, with anexample, how careless application of this method leads to the fallacy ofpost hoc. H. S. ’16, 18
Or, Explain the Method of Difference with an example. H. S. ’20
Ans: The definition of the Method of Difference is—“
If an instance in which the phenomenon occurs and an instance in whichit does not occur have all circumstances in common except one, that onediffering circumstance is the cause or an indispensable part of the cause ofthe phenomenon.”
Example: The weight of a truck with goods is two tons. The weight of thegoods is one and a half tons. Therefore, the weight of the truck alone is half a ton.
If this method is carelessly applied, it may result in the fallacy of post hoc(false cause). Example: On the day a naked fakir came to the village, a man named Bazendied. It was concluded that the arrival of the fakir caused Bazen’s death. Thisis merely a coincidental conjunction, not a causal connection.
6. State the definition of the Joint Method of Agreement andDifference as given by Mill with a real example. Why is it called theDouble Method of Agreement? H. S. ’16
Ans: According to Mill, if among instances where the phenomenon ispresent there is one common circumstance, and among instances where thephenomenon is absent that circumstance is also absent, then that circumstanceis the cause or effect of the phenomenon.
Example: When an electric bell is rung inside a jar filled with air, sound isheard. When the jar is made airless, no sound is heard. Therefore, the presenceof air is the cause of hearing sound. It is called the Double Method of Agreement because it involves agreement in the class of positive instances and agreement in the class of negativeinstances in determining causal relation.
7. Explain the significance of the statement: “The Method ofAgreement is a method of discovery, and the Method of Difference is amethod of proof.” H. S. ’14, ’18
Ans: By the Method of Agreement, certain large-scale natural phenomenasuch as earthquakes, storms, volcanic eruptions, etc., can be analyzed. Thesecannot be subjected to controlled experiments. Therefore, it is called a methodof discovery.
On the other hand, the Method of Difference is called a method of proofbecause through experiment the differing circumstance can be isolated fromthe positive instance and conclusively shown to be the cause or an essential part of the cause.
8. State Mill’s canon of the Method of Concomitant Variations andexplain its disadvantages. H. S. ’18, ’20
Ans: Mill’s canon of the Method of Concomitant Variations is— “If a change in one phenomenon is accompanied by a correspondingchange in another phenomenon, the two are causally connected.” The disadvantages are—
(a) It is not applicable to qualitative changes.
(b) It cannot be applied beyond experience.
(c) It may involve the possible defects of both the Method of Agreement and the Method of Difference.
(d) There is a limit to determining variation in this method.
9. State Mill’s canon of the Method of Difference and describe fourdisadvantages of this method. H. S. ’17, ’18
Ans: Mill’s canon of the Method of Difference is—If an instance in which the phenomenon is present and an instance in whichit is absent agree in all respects except one circumstance, that one differingcircumstance is the cause or an indispensable part of the cause of thephenomenon. Four disadvantages are—
(a) Its field of application is very limited.
(b) It can proceed from cause to effect, but not from effect to cause.
(c) It is not entirely free from the possibility of plurality of causes.
(d) It is very difficult to apply in practice.
10. Define the Method of Agreement in your own words and give areal example where we proceed from effect to cause. Why is it mainlycalled a method of observation? H. S. ’17
Ans: If among two or more instances of a phenomenon under investigationthere is only one common circumstance, and all the instances agree only in that circumstance, then that circumstance is the cause or effect of thephenomenon.
Example: Suppose we want to determine the effect of alcohol consumption. Several individuals who consume alcohol are observed. Though they differin many respects, all are found to have weak kidneys. Therefore, alcohol Consumption may be considered the cause of kidney weakness.
The Method of Agreement is mainly called a method of observationbecause it depends on collecting and comparing instances throughobservation. It cannot ensure that no hidden common factor exists. It onlysuggests a possible causal connection; hence it is not an experimental method.
11. Explain the Method of Residues with an example. Is it animproved form of the Method of Difference? Explain. H. S. ’17, ’19
Ans: According to Mill, if a part of a phenomenon is known by previousinduction to be the effect of certain antecedents, then after subtracting that part, the remaining part of the phenomenon is the effect of the remainingantecedents.
Symbolic example:
A B C produce P Q R
B C produce Q R
Therefore, A is the cause of P.
Here, A cannot be the cause of Q or R, since Q and R occur without A. Amust be the cause of P, because wherever A is present, P is present, and in theabsence of A, P is absent.
The Method of Residues is regarded as a refined or modified form of theMethod of Difference because both are based on the principle of elimination, and it attempts to remove the practical difficulties found in the simple Methodof Difference.
