Welcome, dear students! In this article we present a complete and exam-oriented study of Class 12 Logic and Philosophy Chapter 3 Question Answer | Hypothesis | English Medium | ASSEB. The chapter “Hypothesis” deals with one of the most important tools of scientific reasoning. A hypothesis is a tentative supposition that scientists put forward in order to explain a fact, an event, or a phenomenon whose cause is not yet known. Without a hypothesis, scientific investigation cannot begin, because every enquiry starts with a guess that has to be tested. In this lesson you will learn the meaning, origin, characteristics, conditions, kinds, verification, and importance of hypothesis as well as the difference between hypothesis, theory, and law. The notes have been prepared strictly following the ASSEB (erstwhile AHSEC) Class 12 syllabus and contain Very Short, Short, Long, MCQ, Fill in the Blanks, True/False, Matching, and a glossary section so that students can prepare for both unit tests and the final HS examination with confidence.
Summary of the Chapter
The chapter Hypothesis is a continuation of the discussion on inductive method. After observing some facts, the scientist tries to discover their cause. The first guess about that cause is called a hypothesis. The word “hypothesis” comes from two Greek words “hypo” meaning “under” and “thesis” meaning “placing.” Thus a hypothesis is a supposition placed under a fact in order to explain it.
According to Coffey, “A hypothesis is an attempt at explanation; a provisional supposition made in order to explain scientifically some fact or phenomenon.” J. S. Mill defines hypothesis as “any supposition which we make, either without actual evidence or on evidence avowedly insufficient, in order to endeavour to deduce conclusions in accordance with facts which are known to be real.”
A hypothesis is required because nature does not reveal her secrets at once. We observe certain facts which call for an explanation. To explain them we form a tentative supposition; from this supposition we deduce certain consequences; these consequences are then verified by observation or experiment. If the consequences agree with facts the hypothesis is accepted; if not, it is rejected.
The chapter discusses four stages of hypothesis: (i) observation of facts, (ii) formation of hypothesis, (iii) deductive development, and (iv) verification. It also discusses the conditions of a valid or legitimate hypothesis: it must not be self-contradictory, it must be consistent with established truths, it must be based on facts and refer to a real cause (vera causa), it must be simple, and above all it must be capable of verification.
Logicians have classified hypotheses in different ways. The well known modern logician L. S. Stebbing divides hypotheses into three kinds — Explanatory, Descriptive, and Analogical (sometimes a fourth type, Working hypothesis, is also added). Other writers also speak of hypothesis concerning law, hypothesis concerning agent, hypothesis concerning collocation, crucial hypothesis, barren hypothesis, causal hypothesis, and mathematical hypothesis. Verification of hypothesis may be direct or indirect; when two rival hypotheses contend for acceptance, a crucial instance or “experimentum crucis” is used to decide between them. Finally, the chapter distinguishes a hypothesis from a theory and a law and explains the role of hypothesis in scientific inquiry.
Textbook Question Answer
A. Very Short Answer Type Questions (1 Mark)
1. What is the literal meaning of the word “Hypothesis”?
Answer: The word hypothesis is derived from two Greek words “hypo” (under) and “thesis” (placing); literally it means “placing under” or a supposition placed under a fact.
2. How many stages of hypothesis are there?
Answer: There are four stages of hypothesis.
3. Which is the first stage of hypothesis?
Answer: Observation of facts is the first stage of hypothesis.
4. What is the meaning of “Vera Causa”?
Answer: Vera causa means “true cause” — a real and known cause and not an imaginary one.
5. Who said, “A hypothesis is an attempt at explanation”?
Answer: Coffey said that a hypothesis is an attempt at explanation.
6. According to Stebbing, how many kinds of hypothesis are there?
Answer: According to L. S. Stebbing there are three principal kinds of hypothesis — Explanatory, Descriptive, and Analogical.
7. Give an example of a working hypothesis.
Answer: “Electricity is a fluid” is an example of a working hypothesis.
8. Is hypothesis always provisional in character?
Answer: Yes, a hypothesis is always provisional or tentative in character until it is verified.
9. What is “Experimentum Crucis”?
Answer: Experimentum Crucis means “crucial experiment” — an experiment or instance that decides between two rival hypotheses.
10. Which hypothesis explained the discovery of the planet Neptune?
Answer: The hypothesis concerning agent, framed by Adams and Leverrier about an unknown planet disturbing the orbit of Uranus, led to the discovery of Neptune.
11. Whose hypothesis is the law of gravitation?
Answer: The law of gravitation is the famous hypothesis of Sir Isaac Newton.
12. Hypothesis is also called what kind of guesswork?
Answer: Hypothesis is also called “skilful guesswork” or “intelligent guess.”
13. Which is the last stage of hypothesis?
Answer: Verification is the last stage of hypothesis.
14. Whose definition of hypothesis is — “any supposition which we make, either without actual evidence or on evidence avowedly insufficient”?
Answer: This definition is given by John Stuart Mill (J. S. Mill).
15. Mention one hypothesis based on analogy.
Answer: Maxwell’s electromagnetic theory of light, which is based on the analogy between light waves and electromagnetic waves, is an example of analogical hypothesis.
B. Short Answer Type Questions (2 Marks)
1. Define hypothesis.
Answer: A hypothesis is a provisional or tentative supposition put forward in order to explain scientifically some fact or phenomenon. According to Coffey, “A hypothesis is an attempt at explanation; a provisional supposition made in order to explain scientifically some fact or phenomenon.”
2. Why is hypothesis necessary in science?
Answer: Hypothesis is necessary because the cause of a fact is not always evident from observation. Without a tentative supposition the scientist has nothing to test. Hypothesis acts as a guide that directs further observation and experiment, and so it is the starting point of every scientific enquiry.
3. State the four stages of hypothesis.
Answer: The four stages are — (i) observation of facts, (ii) formation of the hypothesis, (iii) deductive application or development of the hypothesis, and (iv) verification of the hypothesis through observation or experiment.
4. What is meant by a working hypothesis?
Answer: A working hypothesis is a supposition advanced solely for the purpose of carrying on further investigation. It is not believed to be finally true; it is used only as a tool to direct enquiry until a better hypothesis is found. Example: “Electricity is a fluid.”
5. What is an explanatory hypothesis?
Answer: An explanatory hypothesis is one in which an antecedent circumstance is supposed to be the real cause of the phenomenon under investigation. For example, Newton’s hypothesis of gravitation explains why bodies fall to the earth.
6. What is a descriptive hypothesis?
Answer: A descriptive hypothesis is one which describes the manner in which the phenomenon under investigation occurs. It does not point out the cause but gives a systematic description. The Ptolemaic theory of the heavens is a famous descriptive hypothesis.
7. What is meant by analogical hypothesis?
Answer: An analogical hypothesis is one in which what is found to be true of one set of phenomena is supposed to be true of another set of phenomena that resembles the first in some essential respect. Maxwell’s electromagnetic theory of light is an analogical hypothesis.
8. What is a barren hypothesis?
Answer: A barren hypothesis is one which, even if true, leads to no fruitful consequences and cannot be verified. As it has no scientific value, logicians regard it as worthless. The hypothesis of an “ether” filling all space, before its rejection, was sometimes treated as barren.
9. What is a crucial hypothesis?
Answer: A crucial hypothesis is the one which alone among several rival hypotheses is able to explain a particular crucial instance and is therefore accepted as true while the others are rejected.
10. What is meant by “Experimentum Crucis” or Crucial Instance?
Answer: An experimentum crucis or crucial instance is an instance which can be explained by only one of two contending hypotheses and not by the other. It thus acts as a decisive test that helps us choose between rival hypotheses.
11. Distinguish between a hypothesis concerning law and a hypothesis concerning agent.
Answer: In a hypothesis concerning law, the agent is known but the law of its operation is not known (e.g. Newton’s gravitation). In a hypothesis concerning agent, the law is known but the agent is unknown (e.g. discovery of Neptune by Adams and Leverrier).
12. What is a hypothesis concerning collocation?
Answer: A hypothesis concerning collocation is one in which both the agent and the law are known but the arrangement (collocation) of the agents is unknown and is therefore supposed. The Copernican heliocentric theory is the well known example.
13. What is a causal hypothesis?
Answer: A causal hypothesis is a supposition framed about the cause of a particular phenomenon. It states that a definite antecedent is the real cause of the event observed. Newton’s gravitation, framed to explain why bodies fall, is a causal hypothesis.
14. What is a mathematical hypothesis?
Answer: A mathematical hypothesis is a supposition framed in quantitative or mathematical form, usually about the relation between measurable quantities. Kepler’s laws of planetary motion are mathematical hypotheses.
15. What are the two methods of verification of hypothesis?
Answer: The two methods are — (i) Direct verification, in which the hypothesis is tested directly by observation or experiment, and (ii) Indirect verification, in which conclusions deduced from the hypothesis are tested and the truth of the hypothesis is inferred from the truth of those conclusions.
C. Short Answer Type Questions (3 Marks)
1. Why is hypothesis called a “skilful guesswork”?
Answer: A hypothesis is called a “skilful guesswork” because it is a guess, but it is not a wild or random guess. It is made by a trained scientific mind on the basis of careful observation and previous knowledge. Such a guess requires intelligence, imagination and acquaintance with similar phenomena. So the great logician Stanley Jevons remarked that a hypothesis is “a happy guess” or “skilful guesswork.” Although it is provisional, it is guided by reason, and that is why it has scientific value.
2. Briefly explain the origin and need of hypothesis.
Answer: The origin of hypothesis lies in our natural desire to explain unfamiliar facts. When the scientist observes a fact whose cause is unknown, his mind cannot rest until an explanation is found. He therefore frames a tentative supposition. The need of hypothesis is threefold — first, it gives a definite direction to enquiry; second, it enables the scientist to deduce consequences which can be tested; third, it organises scattered facts into a meaningful system. Without hypothesis induction would be blind and observation aimless.
3. State the conditions of a valid hypothesis.
Answer: A valid or legitimate hypothesis must satisfy the following conditions —
(i) it must not be self-contradictory or absurd; it must be conceivable;
(ii) it must not conflict with already established truths and laws;
(iii) it must be based on facts and must refer to a vera causa (a real cause);
(iv) it must be simple — of two equally good hypotheses the simpler one is preferred (Occam’s razor);
(v) it must have predictive power — from it consequences must be deducible; and
(vi) it must be capable of verification, that is, it must be empirically testable.
4. Distinguish between explanatory and descriptive hypothesis.
Answer:
(i) An explanatory hypothesis points out the cause of a phenomenon; a descriptive hypothesis only describes the manner in which the phenomenon occurs.
(ii) Explanatory hypothesis answers the question “why?”; descriptive hypothesis answers the question “how?”
(iii) Newton’s law of gravitation is an explanatory hypothesis; the Ptolemaic geocentric system is a descriptive hypothesis.
(iv) Explanatory hypothesis has greater scientific value because it gives causal connection.
5. Explain “hypothesis concerning agent” with an example.
Answer: A hypothesis concerning agent is one in which the law of operation is known but the agent producing the effect is not known. The astronomers Adams and Leverrier observed certain irregularities in the orbit of the planet Uranus that could not be explained by the gravitational pull of the known planets. They supposed that an unknown planet was disturbing Uranus. Acting on this hypothesis, Galle of the Berlin observatory directed his telescope to the predicted spot and found the new planet Neptune. Here the law (gravitation) was known but the agent (Neptune) was unknown.
6. Explain “hypothesis concerning collocation” with an example.
Answer: A hypothesis concerning collocation is one in which the agents and the law of their operation are both known, but the arrangement (collocation) of these agents is unknown and is therefore supposed. The Copernican heliocentric theory is a striking example. Copernicus knew the heavenly bodies and the laws of motion; what he supposed was a different arrangement — the sun, not the earth, at the centre of the planetary system. This supposition gave a much simpler description of the heavens than the older Ptolemaic arrangement.
7. What do you mean by a “barren” hypothesis? Why is it rejected?
Answer: A barren hypothesis is one from which no testable consequences can be drawn and which therefore yields no fruitful results. Even if such a hypothesis happens to be true, it neither explains the facts nor leads to fresh discoveries. Logicians reject a barren hypothesis because the very purpose of a scientific hypothesis is to explain phenomena and to be verifiable. A hypothesis that cannot be verified has no scientific value and is dismissed as worthless.
8. State the difference between direct and indirect verification.
Answer:
(i) In direct verification, the supposed cause itself is observed in fact; the hypothesis is confirmed by direct observation or experiment.
(ii) In indirect verification, the supposed cause cannot be observed directly; instead, certain consequences are deduced from the hypothesis and these consequences are observed and tested. If they agree with facts, the hypothesis is accepted indirectly.
(iii) Example of direct verification — the existence of Neptune was directly verified by telescopic observation. Example of indirect verification — Newton’s hypothesis of gravitation has been confirmed indirectly by the agreement of its consequences (planetary motions, tides, falling bodies) with facts.
9. What is the role of hypothesis in scientific investigation?
Answer: Hypothesis plays an indispensable role in science.
(i) It gives a starting point and direction to enquiry.
(ii) It serves as a guide to observation and experiment by indicating what to look for.
(iii) It enables the scientist to deduce consequences which can be tested, and so makes induction fruitful.
(iv) It systematises scattered facts under one explanation.
(v) Many great scientific laws, such as Newton’s gravitation and Kepler’s laws of planetary motion, were originally hypotheses; therefore, hypothesis is the seed of every scientific theory.
10. Distinguish between hypothesis and theory.
Answer:
(i) A hypothesis is a tentative supposition not yet verified, while a theory is a hypothesis that has been verified by repeated tests.
(ii) Hypothesis is provisional in character; theory is comparatively well established.
(iii) Hypothesis is the starting point of enquiry; theory is the result of enquiry.
(iv) Newton’s gravitation, when first proposed, was a hypothesis; after repeated verification it became the theory of gravitation.
11. Distinguish between hypothesis and law.
Answer:
(i) A hypothesis is a supposition that requires verification; a law is a uniform relation among phenomena that has been finally established.
(ii) Hypothesis is uncertain and provisional; a law is certain and universal.
(iii) Hypothesis is framed by the mind; a law is discovered in nature.
(iv) Newton’s gravitation, after verification, was accepted as a law of nature.
D. Long Answer Type Questions (5 / 6 Marks)
1. Define hypothesis. Discuss the conditions of a valid hypothesis.
Answer: A hypothesis is a provisional supposition put forward to explain a fact or phenomenon scientifically. Coffey defines it as “an attempt at explanation; a provisional supposition made in order to explain scientifically some fact or phenomenon.” J. S. Mill says it is “any supposition which we make, either without actual evidence or on evidence avowedly insufficient, in order to endeavour to deduce conclusions in accordance with facts which are known to be real.”
For a hypothesis to be valid or legitimate it must satisfy several conditions —
(i) It must not be self-contradictory or absurd. A hypothesis that contradicts itself, e.g. “the same body is at rest and in motion at the same time and in the same respect,” cannot be entertained at all. It must be conceivable and definite.
(ii) It must be consistent with established truths. A hypothesis that contradicts well established laws of nature is not acceptable. For example, a hypothesis denying the law of conservation of energy will be rejected.
(iii) It must be based on facts and must refer to a vera causa. The cause supposed must be a real cause and not an imaginary one. The supposition that “Neptune disturbs the orbit of Uranus” was based on observed irregularities and on the known force of gravitation, both real causes.
(iv) It must be simple. Of two equally good hypotheses the simpler one is preferred. This is the famous principle of “Occam’s razor” — entities should not be multiplied beyond necessity.
(v) It must have predictive power. From a good hypothesis we should be able to deduce consequences which were not originally suggested by the observed facts; if these new consequences also turn out to be true, the hypothesis gains strong support.
(vi) It must be capable of verification. A hypothesis that cannot be tested, even in principle, is not a scientific hypothesis. The whole purpose of a hypothesis is to be confirmed or refuted by observation and experiment.
A hypothesis that fulfils all these conditions is called a legitimate or valid scientific hypothesis.
2. Describe the different stages of hypothesis.
Answer: A hypothesis does not appear suddenly; it is the result of an orderly process. The four stages of hypothesis are —
(i) Observation of facts: This is the first stage. By careful observation, the scientist comes across some facts which call for explanation. Without observation no question would arise and no hypothesis would be needed.
(ii) Formation of the hypothesis: Once the facts are before us, the imagination of the scientist supplies a possible cause or law that may explain them. This supposition is the hypothesis. It is at this stage that the so-called “happy guess” or skilful guesswork comes in. Newton’s seeing the apple fall and supposing a force of gravitation drawing it down is a famous example.
(iii) Deductive development: The hypothesis once formed is not directly tested, because it is too general and abstract. Therefore from it certain particular consequences are deduced by logical reasoning. From the hypothesis of gravitation, for example, we deduce that planets must move in elliptical orbits, that there must be tides, that bodies must fall with accelerated motion, etc.
(iv) Verification: This is the last stage. The deduced consequences are now compared with facts by observation or experiment. If they agree, the hypothesis is confirmed; if not, it is either modified or rejected. Verification may be direct or indirect.
Through these four stages a tentative supposition gradually becomes an established theory. A hypothesis that successfully passes verification at all points may finally be accepted as a law of nature.
It should be noted that these four stages are not always sharply separated in actual practice. Often the scientist moves back and forth between them — observation suggests a hypothesis, the hypothesis directs further observation, fresh facts modify the hypothesis, and so on. The whole process is therefore circular and progressive rather than strictly linear. What is important is that all four elements are essential. If observation is missing, the hypothesis has no factual basis. If the hypothesis itself is missing, observation has no direction. If deduction is missing, the hypothesis cannot be put to the test. And if verification is missing, the hypothesis remains a mere guess. In great scientific discoveries, all four stages are clearly seen — Newton observed falling bodies and the moon’s motion, supposed a universal gravitating force, deduced the elliptical orbits of planets and the periods of comets, and finally the agreement of these deductions with observation gave the law of gravitation.
3. Discuss the various kinds of hypothesis.
Answer: Different logicians have classified hypothesis in different ways. The most important kinds are —
(i) Working hypothesis: A provisional supposition advanced solely to start and carry on enquiry. It is not believed to be finally true. Example — “Electricity is a fluid.”
(ii) Hypothesis as the only possible cause: Sometimes a hypothesis suggests the only cause that can possibly explain the phenomenon, leaving no rival in the field.
(iii) Crucial hypothesis: Among rival hypotheses, the one which alone is able to explain a “crucial instance” and is therefore accepted as true.
(iv) Barren hypothesis: One which yields no testable consequence and is therefore worthless.
(v) Hypothesis concerning agent: Law is known, agent is unknown — discovery of Neptune by Adams and Leverrier.
(vi) Hypothesis concerning law of connection: Agent is known, law is unknown — Newton’s gravitation.
(vii) Hypothesis concerning collocation: Both agent and law are known, but the arrangement is unknown — the Copernican heliocentric theory.
(viii) Causal hypothesis: A supposition about the cause of a phenomenon.
(ix) Mathematical hypothesis: Stated in quantitative form — Kepler’s laws of planetary motion.
According to L. S. Stebbing, hypothesis may also be classified as Explanatory, Descriptive and Analogical. An explanatory hypothesis assigns a cause; a descriptive hypothesis describes the manner of occurrence; and an analogical hypothesis transfers a known truth from one set of phenomena to another set that resembles it. Each of these kinds plays its own part in scientific enquiry.
The above classification is not rigid; one and the same hypothesis may belong to more than one class. For instance, Newton’s gravitation is explanatory because it assigns a cause, mathematical because it is stated in a precise quantitative form, causal because it speaks of a real cause, and at the same time it is a hypothesis concerning the law of connection because the agent (matter) is known and the law (gravitation) is the new supposition. The classification is therefore based on the angle from which the hypothesis is viewed. What is essential is that all genuine hypotheses, however classified, must satisfy the conditions of a valid hypothesis discussed earlier. A hypothesis that is fanciful, self-contradictory, or barren cannot find a place in any of these classes. The variety of types simply shows how widely the method of hypothesis is used in different fields of science — physics, astronomy, chemistry, biology and even social sciences — and how it is the most powerful instrument that the human mind possesses for the discovery of truth.
4. Explain the verification of hypothesis. What is meant by Crucial Instance or Experimentum Crucis?
Answer: Verification means the testing of a hypothesis to find out whether it agrees with facts. Without verification a hypothesis remains a mere guess. Verification is the fourth and final stage of hypothesis. It is of two kinds —
(i) Direct verification: Here the supposed cause itself is observed. For example, Adams and Leverrier supposed an unknown planet to disturb the orbit of Uranus; when the telescope was actually directed to the predicted region of the sky, the planet Neptune was seen. The hypothesis was thus directly verified.
(ii) Indirect verification: Here the supposed cause cannot be observed directly, but the consequences deduced from the hypothesis are observed. If the consequences agree with facts, the hypothesis is regarded as confirmed. Newton’s gravitation cannot be seen, but its consequences — the falling of bodies, the motion of planets, the tides of the sea — agree with facts; therefore, gravitation is indirectly verified.
Crucial Instance / Experimentum Crucis: When two rival hypotheses contend for acceptance, an instance is sometimes found which can be explained by one hypothesis and not by the other. Such an instance is called a “Crucial Instance” or “Experimentum Crucis” (literally “experiment of the cross-roads”). It acts as a decisive test, settling the dispute between the two hypotheses.
A famous example is the comparison between the corpuscular theory of light (Newton) and the wave theory (Huygens). According to the corpuscular theory, light should travel faster in water than in air; according to the wave theory, slower. Foucault’s experiment showed that light actually travels slower in water — a crucial instance against the corpuscular theory and in favour of the wave theory.
However, logicians warn that the value of a crucial instance should not be exaggerated. Sometimes what appears to be a crucial instance is later found to be capable of explanation by the rejected hypothesis also, after suitable modification. Hence even an experimentum crucis gives only a provisional victory to one hypothesis. Final acceptance comes only when the hypothesis has been confirmed by a long series of independent verifications. Verification, whether direct or indirect, and whether by ordinary observation or by crucial experiment, is therefore a continuous process. Even Newton’s law of gravitation, which was confirmed for more than two centuries, was modified in the twentieth century by Einstein’s theory of relativity. This shows that scientific verification is never absolutely final; every hypothesis remains open to further testing and revision.
5. Distinguish between hypothesis, theory and law. Discuss the role of hypothesis in scientific inquiry.
Answer: Although the words hypothesis, theory and law are sometimes used loosely, in logic and science they have distinct meanings.
Hypothesis is a tentative supposition put forward to explain a fact, the truth of which is yet to be tested.
Theory is a hypothesis that has been confirmed by considerable evidence and is accepted as a probable explanation, although it may still admit of refinement.
Law is a uniform relation among phenomena that has been so thoroughly verified that no exception is found; it is regarded as a necessary truth of nature.
The same idea may pass through these three stages. Newton’s gravitation was first a hypothesis, then a theory, and finally a law of nature.
Role of hypothesis in scientific inquiry:
(i) Hypothesis is the starting point of every scientific investigation; without a tentative explanation enquiry cannot begin.
(ii) It directs observation and experiment; the scientist knows what to look for and what to ignore.
(iii) From it, definite consequences can be deduced and tested; this gives induction its method.
(iv) It links scattered facts into a connected system, providing unity and economy of thought.
(v) It has heuristic value — it suggests new researches and leads to new discoveries (the discovery of Neptune is a classical example).
(vi) Even when ultimately rejected, a hypothesis is useful, for the very process of testing it adds to our knowledge.
Therefore, hypothesis is rightly called the “soul of scientific method.” Without it science would be only a collection of unrelated facts.
Additional Important Questions
A. Multiple Choice Questions (MCQ)
1. The word “hypothesis” is derived from —
(a) Latin
(b) Greek
(c) Sanskrit
(d) French
Answer: (b) Greek.
2. “A hypothesis is an attempt at explanation” was said by —
(a) Mill
(b) Coffey
(c) Bain
(d) Stebbing
Answer: (b) Coffey.
3. The number of stages of hypothesis is —
(a) Two
(b) Three
(c) Four
(d) Five
Answer: (c) Four.
4. The first stage of hypothesis is —
(a) Verification
(b) Deduction
(c) Observation of facts
(d) Formation of hypothesis
Answer: (c) Observation of facts.
5. “Vera causa” means —
(a) Imaginary cause
(b) Final cause
(c) True cause
(d) Material cause
Answer: (c) True cause.
6. According to Stebbing, the kinds of hypothesis are —
(a) Two
(b) Three
(c) Four
(d) Five
Answer: (b) Three.
7. “Electricity is a fluid” is an example of —
(a) Causal hypothesis
(b) Working hypothesis
(c) Barren hypothesis
(d) Mathematical hypothesis
Answer: (b) Working hypothesis.
8. The discovery of Neptune is an example of —
(a) Hypothesis concerning law
(b) Hypothesis concerning agent
(c) Hypothesis concerning collocation
(d) Working hypothesis
Answer: (b) Hypothesis concerning agent.
9. Newton’s law of gravitation is an example of —
(a) Hypothesis concerning law
(b) Hypothesis concerning agent
(c) Descriptive hypothesis
(d) Barren hypothesis
Answer: (a) Hypothesis concerning law.
10. The Copernican heliocentric theory is an example of —
(a) Hypothesis concerning law
(b) Hypothesis concerning agent
(c) Hypothesis concerning collocation
(d) Mathematical hypothesis
Answer: (c) Hypothesis concerning collocation.
11. “Experimentum crucis” means —
(a) Easy experiment
(b) Crucial experiment
(c) Useless experiment
(d) Mathematical experiment
Answer: (b) Crucial experiment.
12. The principle “entities should not be multiplied beyond necessity” is known as —
(a) Mill’s canon
(b) Occam’s razor
(c) Newton’s rule
(d) Bacon’s rule
Answer: (b) Occam’s razor.
13. The last stage of hypothesis is —
(a) Observation
(b) Formation
(c) Deduction
(d) Verification
Answer: (d) Verification.
14. Hypothesis is also called —
(a) Wild guess
(b) Skilful guesswork
(c) Established law
(d) Final theory
Answer: (b) Skilful guesswork.
15. A hypothesis that yields no fruitful consequence is called —
(a) Crucial hypothesis
(b) Working hypothesis
(c) Barren hypothesis
(d) Causal hypothesis
Answer: (c) Barren hypothesis.
16. Kepler’s laws of planetary motion are examples of —
(a) Causal hypothesis
(b) Mathematical hypothesis
(c) Working hypothesis
(d) Barren hypothesis
Answer: (b) Mathematical hypothesis.
17. Maxwell’s electromagnetic theory of light is an example of —
(a) Causal hypothesis
(b) Working hypothesis
(c) Analogical hypothesis
(d) Barren hypothesis
Answer: (c) Analogical hypothesis.
18. The Ptolemaic theory of the heavens is an example of —
(a) Explanatory hypothesis
(b) Descriptive hypothesis
(c) Working hypothesis
(d) Barren hypothesis
Answer: (b) Descriptive hypothesis.
19. A hypothesis must be —
(a) Self-contradictory
(b) Imaginary
(c) Verifiable
(d) Useless
Answer: (c) Verifiable.
20. Direct verification of hypothesis is done by —
(a) Imagination
(b) Observation or experiment
(c) Deduction only
(d) Authority
Answer: (b) Observation or experiment.
B. Fill in the Blanks
1. The word “hypothesis” is derived from the ______ language.
Answer: Greek.
2. A hypothesis is a ______ supposition made in order to explain a fact.
Answer: Provisional / tentative.
3. The first stage of hypothesis is ______ of facts.
Answer: Observation.
4. The last stage of hypothesis is ______.
Answer: Verification.
5. “Vera causa” means ______ cause.
Answer: True / real.
6. According to Stebbing, hypothesis is of ______ kinds.
Answer: Three.
7. “Electricity is a fluid” is an example of ______ hypothesis.
Answer: Working.
8. Newton’s law of gravitation is a hypothesis concerning ______.
Answer: Law / law of connection.
9. The discovery of Neptune was based on a hypothesis concerning ______.
Answer: Agent.
10. The Copernican heliocentric theory is a hypothesis concerning ______.
Answer: Collocation.
11. A hypothesis that yields no fruitful consequence is called ______.
Answer: Barren hypothesis.
12. The crucial test of a hypothesis is called ______.
Answer: Experimentum crucis / crucial instance.
13. The principle of preferring the simpler hypothesis is called ______.
Answer: Occam’s razor.
14. A hypothesis that has been thoroughly verified is called a ______.
Answer: Theory / law.
15. Hypothesis is called the ______ of scientific method.
Answer: Soul.
C. True or False
1. A hypothesis is a wild and random guess.
Answer: False. (It is a skilful, intelligent guess based on facts.)
2. A hypothesis is provisional in character.
Answer: True.
3. The first stage of hypothesis is verification.
Answer: False. (The first stage is observation of facts.)
4. A hypothesis must be self-contradictory.
Answer: False. (A valid hypothesis must be free from self-contradiction.)
5. A hypothesis must be capable of verification.
Answer: True.
6. “Vera causa” means imaginary cause.
Answer: False. (It means true or real cause.)
7. Stebbing classified hypothesis into four kinds.
Answer: False. (Stebbing classified hypothesis into three kinds.)
8. A barren hypothesis has no scientific value.
Answer: True.
9. Newton’s gravitation is an example of working hypothesis.
Answer: False. (It is a hypothesis concerning law / explanatory hypothesis.)
10. The discovery of Neptune is an example of hypothesis concerning agent.
Answer: True.
11. An experimentum crucis decides between two rival hypotheses.
Answer: True.
12. A hypothesis is the same as a law of nature.
Answer: False. (A hypothesis is provisional; a law is fully established.)
13. Hypothesis directs observation and experiment.
Answer: True.
14. A good hypothesis must conflict with established truths.
Answer: False. (A good hypothesis must be consistent with established truths.)
15. Without hypothesis, scientific investigation cannot begin.
Answer: True.
D. Match the Following
| Column A | Column B |
|---|---|
| 1. Vera causa | (a) True cause |
| 2. Working hypothesis | (b) Electricity is a fluid |
| 3. Hypothesis concerning agent | (c) Discovery of Neptune |
| 4. Hypothesis concerning law | (d) Newton’s gravitation |
| 5. Hypothesis concerning collocation | (e) Copernican heliocentric theory |
| 6. Mathematical hypothesis | (f) Kepler’s laws of planetary motion |
| 7. Analogical hypothesis | (g) Maxwell’s electromagnetic theory |
| 8. Descriptive hypothesis | (h) Ptolemaic theory of the heavens |
| 9. Experimentum crucis | (i) Crucial instance / decisive test |
| 10. Occam’s razor | (j) Simpler hypothesis is preferred |
Answer: 1 – (a), 2 – (b), 3 – (c), 4 – (d), 5 – (e), 6 – (f), 7 – (g), 8 – (h), 9 – (i), 10 – (j).
E. Match the Logician with the Statement
| Column A | Column B |
|---|---|
| 1. Coffey | (a) “A hypothesis is an attempt at explanation; a provisional supposition made in order to explain scientifically some fact or phenomenon.” |
| 2. J. S. Mill | (b) “Any supposition which we make in order to deduce conclusions in accordance with facts which are known to be real.” |
| 3. L. S. Stebbing | (c) Classified hypothesis into Explanatory, Descriptive, and Analogical. |
| 4. Newton | (d) Hypothesis of universal gravitation. |
| 5. Adams and Leverrier | (e) Hypothesis leading to discovery of Neptune. |
| 6. Copernicus | (f) Heliocentric arrangement of the solar system. |
| 7. Kepler | (g) Mathematical hypothesis on planetary motion. |
| 8. Maxwell | (h) Analogical hypothesis on electromagnetic nature of light. |
Answer: 1 – (a), 2 – (b), 3 – (c), 4 – (d), 5 – (e), 6 – (f), 7 – (g), 8 – (h).
F. Additional Long Answer Questions
1. Why is hypothesis indispensable in inductive reasoning? Discuss with examples.
Answer: Inductive reasoning proceeds from particular facts to general laws. But mere observation of facts does not by itself give a general law; the mind must seek a connecting principle that explains why those facts occur. This connecting principle, before it is verified, is a hypothesis. Hypothesis is therefore indispensable to induction in the following ways —
(i) It provides a tentative law that explains the observed facts and unifies them under one principle.
(ii) It enables the scientist to deduce additional consequences which can be tested. Without such deductions induction would have no method of self-correction.
(iii) It directs further observation by telling the investigator what kind of new facts to look for.
(iv) It bridges the gap between observed cases and unobserved cases — an essential feature of induction.
For example, after observing that bodies fall to the earth, that the moon moves round the earth, and that the planets move round the sun, Newton supposed a universal force of gravitation. This hypothesis was the connecting principle which made these scattered facts into one inductive generalization. Without such a hypothesis, the facts would have remained isolated. Hence Whewell rightly remarked that “no scientific induction is possible without hypothesis.”
2. Explain the various sources from which a hypothesis is suggested.
Answer: Hypotheses do not arise out of nothing; they are suggested to the mind by various sources. The chief sources of hypothesis are —
(i) Observation: Careful observation of facts often suggests their probable cause. The fall of an apple suggested to Newton the hypothesis of gravitation.
(ii) Analogy: Resemblance between two phenomena suggests that what is true of one may be true of the other. Light was supposed to be a wave by analogy with sound.
(iii) Previous knowledge: Familiarity with similar cases enables the scientist to frame a likely supposition. The discovery of Neptune was suggested by the previous knowledge of gravitation.
(iv) Imagination: Scientific imagination plays a great role; without it new ideas cannot arise. Einstein’s hypothesis about light bending in a gravitational field is a product of bold imagination.
(v) Accident: Sometimes a chance observation suggests a hypothesis. The germ theory of disease was partly suggested by the chance observation of mould killing bacteria.
Whatever the source, the hypothesis must in the end be tested by observation and experiment. Logicians remind us that the source from which a hypothesis comes is not important; what is important is whether it can stand the test of verification.
3. Discuss the importance and limitations of hypothesis in science.
Answer: Importance: Hypothesis is the very foundation of scientific method. (i) It gives a starting point to enquiry. (ii) It makes induction methodical and fruitful. (iii) It enables the scientist to deduce consequences and test them. (iv) It binds together scattered facts into a coherent system. (v) It has heuristic value, leading to fresh discoveries. (vi) Many of the greatest laws of science (gravitation, evolution, atomic theory) began as hypotheses.
Limitations: Despite its importance, hypothesis has certain limitations. (i) A hypothesis is only a guess, however skilful, and may turn out to be false. (ii) Wrong hypotheses sometimes mislead the scientist for a long time, as the phlogiston hypothesis did before Lavoisier. (iii) An untestable hypothesis is worthless. (iv) Even verified hypotheses are not absolutely final; they may be modified by further evidence, as Newton’s gravitation was modified by Einstein. (v) An incautious hypothesis may bias observation, making the scientist see what he wishes to see. The remedy lies in strict adherence to the conditions of a valid hypothesis and in continuous verification.
Glossary of Important Terms
| Term | Meaning |
|---|---|
| Hypothesis | A provisional or tentative supposition put forward to explain a fact or phenomenon scientifically. |
| Vera Causa | A “true cause” — a real and known cause, not a mere imaginary one. |
| Observation | The careful examination of facts that calls for an explanation; the first stage of hypothesis. |
| Deduction | The process of drawing particular consequences from a general hypothesis. |
| Verification | The testing of the hypothesis by comparing its consequences with facts; the last stage. |
| Direct Verification | Verification by directly observing the supposed cause itself. |
| Indirect Verification | Verification by testing the consequences deduced from the hypothesis. |
| Working Hypothesis | A hypothesis adopted only as a starting point or tool for further investigation. |
| Explanatory Hypothesis | A hypothesis which assigns a cause for a phenomenon. |
| Descriptive Hypothesis | A hypothesis which describes the manner in which a phenomenon occurs. |
| Analogical Hypothesis | A hypothesis which transfers a known truth from one set of phenomena to another similar set. |
| Crucial Hypothesis | The hypothesis which alone explains a crucial instance and is therefore accepted. |
| Barren Hypothesis | A hypothesis from which no fruitful or testable consequences can be drawn. |
| Hypothesis Concerning Agent | A hypothesis where the law is known but the agent is unknown (e.g. Neptune). |
| Hypothesis Concerning Law | A hypothesis where the agent is known but the law of its operation is unknown (e.g. gravitation). |
| Hypothesis Concerning Collocation | A hypothesis where the agents and the law are known but the arrangement is unknown (e.g. Copernican theory). |
| Causal Hypothesis | A hypothesis framed about the cause of a phenomenon. |
| Mathematical Hypothesis | A hypothesis stated in quantitative or mathematical form (e.g. Kepler’s laws). |
| Experimentum Crucis | A decisive experiment or instance which settles the dispute between two rival hypotheses. |
| Occam’s Razor | The principle that of two equally good hypotheses the simpler one is to be preferred. |
| Theory | A hypothesis that has been confirmed by considerable evidence and is accepted as a probable explanation. |
| Law | A uniform relation among phenomena that has been thoroughly established and admits of no known exception. |
| Skilful Guesswork | Another name given to hypothesis, indicating that it is an intelligent and trained guess. |
Dear students, this completes our detailed discussion of Class 12 Logic and Philosophy Chapter 3 Question Answer | Hypothesis | English Medium | ASSEB. Revise the four stages, the conditions of a valid hypothesis, the kinds of hypothesis (especially Stebbing’s classification and the hypotheses concerning agent, law, and collocation), the methods of verification, and the difference between hypothesis, theory and law. Practise the MCQs, fill in the blanks, true/false, and matching exercises given at the end. A clear understanding of this chapter will not only help you score full marks in the HS examination but also build the foundation of scientific thinking. Best wishes for your studies and your examinations!