popper falsification

Falsification

A. V. Ravishankar Sarma

IIT Kanpur

September 1, 2015

Revised: September 1, 2015

A. V. Ravishankar Sarma (IIT Kanpur)Karl Popper 1/ 64 September 1, 2015 1 / 64

Karl Popper

1 Karl Popper is primarily a philosopher of science.

2 He is primarily interested in how our knowledge grows.

3 He has a high regard for science and thinks that the best way tostudy the growth of knowledge is to study the growth of scientificknowledge.

4 Science grows by a process of conjectures and refutations


Einstein’s Influence on Popper

Influence of Einstein’s views1 Einstein regarded his theory as merely a step forward and one

which would be replaced by a more comprehensive theory.

2 Einstein would regard his theory as refuted if it failedexperimental tests


Karl Popper (1902-1995)

1 1928: PhD Dissertation: On the Problem of Method in thePsychology of Thinking.

2 Methodology of science is exclusively a matter of logic andobjective knowledge instead of psychology.

3 Influenced by Einstein, and Marx’s theory of history, Freud’stheory of psychoanalysis, and Alfred Adler’s theory calledindividual psychology.

4 Correct attitude for Science: Falsification

5 Some important Works: The logic of Scientific discovery,Objective knowledge, open societies and its enemies.

6 Critical Rationalism: Criticism is the mark of Scientific rationality.Hypotheses is legitimate as long as it is refutable.


Excerpt from Conjectures and refutations

Since the autumn 1919 when I first begin to grapple with theproblem, When should a theory be ranked as scientific? or Isthere a criterion for the scientific character or status of atheory?The problem which troubled me at the time was neither, Whenis a theory true? nor When is a theory acceptable?my problem was different. I wished to distinguish betweenscience and pseudo-science; knowing very well that scienceoften errs, and that pseudoscience may happen to stumble onthe truth.I often formulated my problem as one of distinguishing between a

genuinely empirical method and a non-empirical or even

pseudo-empirical method that is to say, a method which, although it

appeals to observation and experiment, nevertheless does not come

up to scientific standards.


Popper’s Approach

1 His proposal was a critical response to the criterion, propoundedby the Vienna Circle, that scientific knowledge is what isempirically verifiable.

2 Karl Popper proposed falsifiability as the criterion with which todemarcate empirical science from nonscientific pursuits such aslogic & mathematics, metaphysics, and pseudoscience.


Critical Rationalism

Hume’s Problem

Evidence transcending belief is unreasonable

Hume’s Argument1 Hume’s inductive scepticism: Are we justified in believing that

unexperienced instances of certain kinds of things will be likeexperienced instances? And if so, how?

2 The justificationist principle that it is reasonable to believe onlywhat you can justify.

Critical rationalism, which accepts (1) but rejects (2).


Popper’s theory of Science

1 Anti-Inductivist

2 Falsificationist.

3 Induction is not just irrational. Induction is a myth. Real sciencedoesn’t (and shouldn’t) employ induction.

4 Scientific hypotheses are never confirmed by evidence. Observingpositive instances of a hypothesis never raises its probability

5 Testing scientific hypotheses is a deductive procedure. Inparticular, tests are attempts to refute a hypothesis.

6 If the observation does not falsify the hypothesis, then thehypothesis does not become probable. It becomes corroborated.

7 Corroborated is a hypothesis that i) has not yet been refuted andii) has stood up severe tests (i.e., attempts at refutation)


Modus Ponens

MP: Example

If Socrates is a man then Socrates is mortal. Socrates is a man.Therefore, Socrates is mortal

Modus Tollens

If Socrates is a god, then Socrates is immortal. Socrates is notimmortal. Therefore, Socrates is not a god.

Karl Popper’s philosophy of science uses modus tolens as the centralmethod of disconfirming, or falsifying, scientific hypotheses.


Popper’s emphasis on Deduction

1 Scientists start with a current scientific theory and use the usualmethods of deductive reasoning to derive specific conclusions, ofwhich some are predictions.

2 Starting with a theory and deducing predictions can be stated inthe form of a premise:

3 If the theory is true, then the prediction is true.

4 Popper shows that we cannot prove that a theory is true, but wecan certainly show that a prediction is false. If the scientist testsone of these predictions and finds out that it is not true.


Popper’s Scientific Method

Methodology of falsification

If the theory is true, then the prediction is true. The prediction is nottrue.Therefore, the theory is not true.


Scientific Method

The actual method of science, Popper maintained, is a continuousprocess of conjecture and refutation:The way in which knowledge progresses, and especially our

scientific knowledge, is by unjustified (and unjustifiable)

anticipations, by guesses, by tentative solutions to our

problems, by conjectures. These conjectures are controlled

by criticism; that is, by attempted refutations, which

include severely critical tests. They may survive these

tests; but they can never be positively justified: they

can be established neither as certainly true nor even as

’probable’


Remark

The criterion of the scientific status of a theory is its falsifiability, orrefutability, or testability.


Popper’s conclusions on Scientific Method

1 It is easy to obtain confirmations, or verifications, for nearly everytheory- if we look for confirmations.

2 Confirmations should count only if they are the result of riskypredictions; that is to say, if, unenlightened by the theory inquestion, we should have expected an event which wasincompatible with the theory–an event which would have refutedthe theory. (3) Every good’ scientific theory is a prohibition: itforbids certain things to happen. The more a theory forbids, thebetter it is.

3 A theory which is not refutable by any conceivable event isnonscientific. Irrefutability is not a virtue of a theory (as peopleoften think) but a vice.


Summary

1 Every genuine test of a theory is an attempt to falsify it, or torefute it. Testability is falsifiability; but there are degrees oftestability: some theories are more testable, more exposed torefutation, than others; they take, as it were, greater risks.

2 Confirming evidence should not count except when it is the resultof a genuine test of the theory; and this means that it can bepresented as a serious but unsuccessful attempt to falsify thetheory. (I now speak in such cases of ’corroborating evidence’.)

3 Some genuinely testable theories, when found to be false, are stillupheld by their admirers–for example by introducing ad hoc someauxiliary assumption, or by re-interpreting the theory ad hoc insuch a way that it escapes refutation. Such a procedure is alwayspossible, but it rescues the theory from refutation only at the priceof destroying, or at least lowering, its scientific status. (I laterdescribed such a rescuing operation as a conventionalist twist or a’conventionalist stratagem’.)


Reference

SCIENCE: CONJECTURES AND REFUTATIONS KARL POPPER,A lecture given at Peterhouse, Cambridge, in Summer 1953, as part ofa course on Developments and trends in contemporary Britishphilosophy, organized by the British Council; originally publishedunder the title ’Philosophy of Science: a Personal Report’ in BritishPhilosophy in Mid-Century, ed. C. A. Mace, 1957.


Refutation

In so far as scientific statements refer to the world of

experience, they must be refutable ... in so far as they

are irrefutable, they do not refer to the world of

experience"


Conjectures and Refutations

1 Scientists stumble over some empirical problem.

2 A theory is proposed (conjectured) as an attempt to solve theproblem (tentative solution).

3 The theory is tested by attempted refutations (error elimination).4. If the theory is refuted, then a new theory is conjectured inorder to solve the new problems.

4 If the theory is corroborated, then it is tentatively accepted. (Butits not established, justified, probable and the like. It is justunrefuted.


Example: Newtons theory of gravitation

1 It was conjectured in an attempt to solve the problem of derivingand explaining Kepler’s laws and Galileo’s laws.

2 The theory solves this problem, but when it is further tested,(attempted refutations) it failed to solve the problem of thehaphazard motion of Mercury’s Perihelion.

3 A new theory is conjectured (Einsteins General Theory ofRelativity) which attempts to solve this problem.


Critical Rationalism

1 Popper regarded a critical attitude as the most important virtue aphilosopher could possess. Indeed, he called criticism the lifebloodof all rational thought.

2 Our knowledge cannot and need not be justified. Criticalrationalism appeal to reason and the role of criticism.

3 Knowledge progresses by conjectures and refutations, by boldattempts at solving problems checked by thorough anduncompromising tests.

4 There is no method of discovering true theories (a recurrentillusion in Western philosophy: Plato, Aristotle, Francis Bacon,Rene Descartes, and John Stuart Mill, to mention but a few).

5 We ascertain the truth of a scientific hypothesis: we can neververify it. Neither (a still weaker version) can we ascertain whethera hypothesis is probable, or probably true.


Context of Discovery

1 Context of Discovery Concerned with origin of hypotheses, isproperly a matter for psychology and that it answers to noparticular logic but is the product of the inspiration of genius.

2 Diverse sources: Metaphysical beliefs, religious teachings, Dreamsetc.

3 Examples: Kepler’s mysticism, Newtons Alchemy, Kekule’sdreams.

4 Influencing factors: Emotional, financial, social, political, cultural.


Context of Justification

1 Naive inductivism: How to test a scientific theory as true. Howscientists ought to generate them?

2 Hall mark of Rationality: Verificationism, Confirmation,


Edifice of Science does not rest on solid bedrock

The empirical basis of objective science has [ . . . . . . ] nothing absoluteabout it. Science does not rest upon solid bedrock. The bold structureof its theories rises, as it were, above a swamp.It is like a building erected on piles. The piles are driven down fromabove into the swamp, but not down to any natural or given base;and if we stop driving the piles deeper, it is not because we havereached firm ground. We simply stop when we are satisfied that thepiles are firm enough to carry the structure, at least for the time being.


Progress of Science

1 Science starts with problems: Problems associated withexplanation and behaviour of some aspects of the world.

2 Falsifiable hypotheses are proposed (conjectures).

3 Conjectured hypotheses are criticized and tested (rigorousless andruthlessly).

4 Subject to more stringent criticism, testing.

5 It progresses by means of conjectures and refutations.

6 Only fittest theories survive. It is considered to be best availabletheory (eg: Einsteins general theoiry of relativity).


Hypotheses: Examples

Scientific Hypotheses

Scientific hypotheses are normally universal generalisations. Testingscientific hypotheses is a deductive procedure. In particular, tests areattempts to refute a hypothesis.Corroborated is a hypothesis that i)has not yet been refuted and ii) has stood up severe tests (i.e.,attempts at refutation).

1 All Ravens are Black,

2 All pendula are such that their period satisfies the equationT = 2π (l/g)1/2.

3 All atoms are composed of a nucleus and orbiting electrons.


Popper’s method of Falsificaion

Testing Hypotheses

1 H (hypothesis to be tested)

2 C (Initial Conditions)

3 ∴ O (Observational consequence; prediction)

4 If O, then H is unrefuted (corroborated); if ¬O, then H getsfalsified


Popper in Logic of scientific discovery

. . . . . . It should be noticed that a positive decision can only temporarilysupport the theory,for subsequent negative decisions may always overthrow it. So long asa theory withstands detailed and severed tests and is not subsequentlysuperseded by another theory in the course of scientific progress, wemay say that it has proved its mettle or that it is corroborated by pastexperience.


Falsification

Popper’s main point is the extremely elementary logical point that ifone takes the business of science as deducing observationalconsequences from statements of laws and theories and initialconditions, no amount of particular positive observational outcomeswill ever prove (or verify) the truth of universal hypotheses or laws, forall such attempted inferences commit the well-known fallacy ofaffirming the consequent. However, even a single negative observationalconsequence allows us to validly infer that the conjunction of laws andinitial conditions from which it is deduced cannot all be true.


Logical Point infavour of falsificationism

1 Even if we assume that true observational statements are availableto us in some way, it is never possible to arrive at universal lawsand theories by logical deductions on that basis alone.

2 However, it is possible to perform logical deductions starting fromsingular observation statements as premises, to arrive at the falsityof universal laws and theories by logical deduction.

Example (Valid Deduction)

Premise: A raven, which was not black, was at place x at time t.Conclusion: Not all ravens are black


Falsification:

Thus theories can be refuted or falsified, by the well known validprinciple of inference known as modus tollens.Observational evidence can never prove any general theories are true,but it can falsify them.For this reason Popper’s model of justification is known asFalsificationism.


Criteria of Falsifiability

1 An hypothesis is falsifiable if there exists a logically possibleobservation statement or set of observation statements that areinconsistent with it, that is, which, if established as true, wouldfalsify the hypothesis.

2 Scientific theories are falsifiable in that they entail observationalpredictions (potential falsifiers) that can be tested and eithercorroborate or falsify the theory.On the contrary, non-scientific claims do not have potentialfalsifiers.

3 If it is to form part of science, an hypothesis must be falsifiable.


Demarcation

A basic statement is to be understood as a particularobservation-report, then we may say that a theory is scientific if andonly if it divides the class of basic statements into the following twonon empty sub-classes:

1 the class of all those basic statements with which it is inconsistent,or which it prohibits - this is the class of its potential falsifiers (i.e.those statements which, if true, falsify the whole theory)

2 the class of those basic statements with which it is consistent, orwhich it permits (i.e. those statements which, if true, corroborateit, or bear it out).


Assertions that are falsifiable

1 It never rains on Wednesdays.

2 All substances expand when heated.

3 Heavy objects such as a brick when released near the surface ofthe earth fal l straight downwards if not impeded,

4 When a ray of light is reflected from a plane mirror, the angle ofincidence is equal to the angle of reflection


Assertions not falsifiable

1 Either it is raining or it is not raining.

2 All points on a Euclidean circle are equidistant from the centre.

3 Luck is possible in sporting speculation.

4 God has no cause.

5 All bachelors are unmarried.

6 Human beings have free will

If a statement is unfalsifiable, then the world can have any propertieswhatsoever.


Good Theory

A good Scientific theory

A very good theory will be one that makes very wide ranging claimsabout the world, and which is consequently highly falsifiable, and isone that resists falsification whenever it is put to the test.

Examples

1 (a) Mars moves in an ellipse around the sun. (b) All planets movein ellipses around their sun.

2 (b) has a higher status than (a) as a piece of scientific knowledge,Law (b) tells us all that (a) tells us and more besides. Law (b),the preferable law, is more falsifiable than (a).

3 Newtonian theory is preferred over Kepler’s theory.


Why Newtonian Theory over Kepler’s theory?

1 Kepler’s Theory(KT): Keplers laws and other initial conditions.Potential falsifiers of Kepler’s theory consist of sets of statementsreferring to planetary positions relative to the sun at specifiedtimes.

2 Newtonian Theory(NT):It consists of Newton’s laws of motionplus his law of gravitation.

3 Potential Falsifiers for NT:Not just Sets of statements of planetarypositions at specified times. But there are many others, referringto the behaviour of falling bodies and pendulums, the correlationbetween the tides and the locations of the sun and moon.


Theory Choice

Highly falsifiable theories should be preferred to less falsifiable ones,then, provided they have not in fact been falsified.Theories that have been falsified must be ruthlessly rejected.The enterprise of science involves the proposal of highly falsifiablehypotheses, followed by deliberate and tenacious attempts to falsifythem.


Popper: Conjectures and Refutations, pp269

[F]alsificationists like myself much prefer an attempt to solve aninteresting problem by a bold conjecture, even (and especially) if itsoon turns out to be false, to any recital of a sequence of irrelevanttruisms.We prefer this because we believe that this is the way in which we canlearn from our mistakes; and that in finding that our conjecture wasfalse we shall have learnt much about the truth, and shall have gotnearer to the truth.


Summary

1 It is easy to obtain confirmations, or verifications, for nearly everytheory -if we look for confirmations.

2 Confirmations should count only if they are the result of riskypredictions; that is to say, if, unenlightened by the theory inquestion, we should have expected an event which wasincompatible with the theory an event which would have refutedthe theory.

3 Every good” scientific theory is a prohibition: it forbids certainthings to happen. The more a theory forbids, the better it is.

4 A theory which is not refutable by any conceivable event isnon-scientific. Irrefutability is not a virtue of a theory (as peopleoften think) but a vice.


Main conclusions

1 Every genuine test of a theory is an attempt to falsify it, or torefute it. Testability is falsifiability; but there are degrees oftestability: some theories are more testable, more exposed torefutation, than others; they take, as it were, greater risks.

2 Confirming evidence should not count except when it is the resultof a genuine test of the theory; and this means that it can bepresented as a serious but unsuccessful attempt to falsify thetheory. (I now speak in such cases of corroborating evidence.)


Some Genuinely testable theories

Some genuinely testable theories, when found to be false, are stillupheld by their admirers.for example by introducing ad hoc some auxiliary assumption, or byreinterpreting the theory ad hoc in such a way that it escapesrefutation.Such a procedure is always possible, but it rescues the theory fromrefutation only at the price of destroying, or at least lowering, itsscientific status. (I later described such a rescuing operation as aconventionalist twist or a conventionalist stratagem.)


Problem with Pseudo scientific theories

1 It is just too easy to accumulate positive instances which supportsome theory, especially when the theory is so general in its claimsthat its seems not to rule anything out.

2 It is hard to see what would not count as supporting evidence fortheir claims.

3 These are over impressed with explanatory power and seeconfirmations everywhere.

4 they do not make precise predictions, and any phenomena thatoccur can be accounted for.


Marxism

1 Marx (1818-1883) Base not only controls the superstructure butdetermines it.

2 Important consequence: Ruling class has no interest in ensuringdecent living and working conditions for the poor.

3 Conflicting situation: various measures to safeguard the safety andwelfare of workers were introduced in England in the nineteenthcentury.

4 some Marxists have argued that, in fact, the introduction of thepoor laws and so on confirm Marxism because they show that thecapitalists were aware of the imminence of the proletarianrevolution and were trying to placate the workers in order to stopor delay it.


Adler’s theory

Human actions are motivated by feelings of inferiority of some kind.Let us take the following incident:

Incident

A man is standing on the bank of a treacherous river at the instant afalls into a river nearby. The man will either leap into the river in anattempt to save the child orhe will not.

Sigmund Freud

Freud could explain the first by positing that the man suffered fromrepression, and the second by saying he had achieved sublimation.


Adler’s theory is not falsifiable.

Case: 1

If he does leap in , the Adlerian respoonds by indicating how hesupports this theory. The man obviously needed to overcome hisfeeling of inferiority by demonstrating that he was brave enough toleap into the river, in spite of danger.

case 2

If the Man does not leap in, the Adlerian can again claim support forthis incident in he theory. The man was overcoming his feelings ofinferiority by demonstrating that he had the strength of will to remainon the bank, unperturbed, while the child is drowned.

X is consistent with any kind of behaviour.


Einstein’s General Theory of Relativity:1917

1 Novel Prediction:which were predictions of new types ofphenomena or entities.

2 Example: The light passing close to the Sun ought to have itspath bent by the Sun’s gravitational field.

3 Admirable thing: Bold conjecture- it made risky prediction, whichcould have made the theory/hypotheses false.

4 genuine scientific theories is that they make precise predictions ofsurprising phenomena and genuine scientists are prepared to rejectthem if their predictions are not borne out by experiments.


Einstein general theory of Relativity

1 Eddington’s solar eclipse observations in 1919 brought the firstimportant test to bear upon Einstein’s relativity theory ofgravitation.

2 Had Eddington’s observations showed that the predicted effect isdefinitely absent, then Einstein’s theory would simply have beenrefuted.

3 Risk in Einstein’s case was very great, since the predicted effectwas different from what was expected from Newton’s theory, whichhad long demonstrated great success culminating with thediscovery of the planet Neptune.


From Autobiography

. . . . . .What impressed me most was Einstein’s own clear statement thathe would regard his theory as untenable if it should fail in certain tests.. . . . . . Thus I arrived, by the end of 1919, at the conclusion that thescientific attitude was the critical attitude, which did not look forverifications but for crucial tests; tests which could refute the theorytested, though they could never establish it


Problem with confirmation

1 If you are in the grip of a theory it is easy to find confirminginstances, especially if the theory is seem to have greatexplanatory power are suspect precisely because so much can beexplained by them.

2 Marxism and psychoanalysis are over-impressed with explanatorypower and see confirmations everywhere.

3 Marxists and psychoanalysts are also sometimes inclined to side-step intellectual critique because their theories explain why peoplewill oppose them.


Popper on Induction

Science is fundamentally about falsifying rather than confirmingtheories, and so he thought that science could proceed withoutinduction because the inference from a falsifying instance to the falsityof a theory is purely deductive.Popper argued that a theory that was, in principle, unfalsifiable byexperience was unscientific.


Three Conditions

Replacement of one theory with other1 The new theory should proceed from some simple, new and

powerful, unifying idea about some connection or relation (such asgravitational attraction) between hitherto unconnected things(such as planets and apples) or facts (such as inertial andgravitational mass) or new ’theoretical entities’ (such as field ndparticles).

2 Secondly, we require that the new theory should be independentlytestable...it must lead to the prediction of phenomena which havenot so far been observed.

3 Thirdly, it should pass some new and severe tests


Scientific Progress

I suggested that science would stagnate, and lose its empiricalcharacter, if we should fail to obtain refutations . . . . . . for very similarreasons science would stagnate and lose its empirical character, if weshould fail to obtain verifications of new predictions. (Popper, 1963,244)


Falsification

1 If a theory or hypothesis is in principle unfalsifiable by experiencethen according to Popper is it unscientific (although it may still bemeaningful)

2 Science proceeds not by testing a theory and accumulatingpositive inductive support for it, but by trying to falsify theories.

3 If it is falsified then it is abandoned, but if it is not falsified thisjust means it ought to be subjected to more attempts to falsify it.

4 Scientists must state clearly the conditions under which theywould give up their theories rather than being committed to themcome what may.


Problems with Falsification

1 Some legitimate parts of science seem not to be falsifiable.Probabilistic statements, Existential statements, unfalsifiablescientific principles, hypotheses of natural selection.

2 Falsificationism is not itself falsifiable.

3 The notion of degree of falsifiability is problematic.

4 Falsificationism cannot account for our expectations about thefuture.

5 Scientists sometimes ignore falsification. In the history of sciencewhere a falsifying observation is tolerated for decades.


Quine-Duhem’s Problem

1 Pierre Duhem (1861-1916): The Aim and Structure of PhysicalTheory (1954).

2 The aim of the enterprise:Representation and classification ofexperimental laws.

3 Agreement with experiment is the sole criterion of truth for aphysical theory’.

The aim of all physical theory is the representation ofexperimental laws. The words truth and certainty have onlyone signification with respect to such a theory; they expressconcordance between the conclusions of the theory and therules established by the observers. Moreover, a law of physicsis but the summary of an infinity of experiments that havebeen made or will be performable. (Duhem, 1954, 144)


Development of Physical Theory:

1 The definition and measurement of physical magnitudes. Thescientist identifies the simplest properties in physical processes andfinds ways to measure them so they can be depicted in symbolicform in mathematical equations.

2 The selection of hypotheses. The scientist builds hypotheses toaccount for the relationships formulated in the previous stage.These are the grounds on which further theories are built, ’theprinciples in our deductions’ (ibid, 30).

3 The mathematical development of the theory. This stage isregulated purely by the requirements of algebraic logic withoutregard to physical realism.

4 The comparison of the theory with experiment.


Relation between Theory and Experiment

1 An experiment in physics is not simply the observation of aphenomenon; it is, besides, the theoretical interpretation of thisphenomenon.

2 The result of an experiment in physics is an abstract and symbolicjudgement.

3 The theoretical interpretation of a phenomenon alone makespossible the use of instruments.

4 Experiment in physics is less certain but more precise and detailedthan the non-scientific establishment of a fact.

theory-dependence of observation


Duhem-Quine Thesis

Thesis

An experiment in physics can never condemn an isolated hypothesisbut only a whole theoretical group and ’A crucial experiment isimpossible in physics.

Logic of Testing

A physicist disputes a certain law; he calls into doubt a certaintheoretical point. How will be justify these doubts? From theproposition under indictment he will derive the prediction of anexperimental fact; he will bring into existence the conditions underwhich this fact should be produced; if the predicted fact is notproduced, the proposition which served as the basis of the predictionwill be irremediably condemned.


Logical Form of Testing

1 Let H be a hypothesis under test, with {A1, A2, A3} etc asauxiliary hypotheses whose conjunction predicts an observation O.

2 {H.A1.A2.A3...} → O.

3 ¬O4 In this situation logic (and this experiment) do not tell us whether

H is responsible for the failure of the prediction or whether thefault lies with A1 or A2 or A3 .


Summary

In sum, the physicist can never subject an isolated hypothesis toexperimental test, but only a whole group of hypotheses; when theexperiment is in disagreement with his predictions, what he learns isthat at least one of the hypotheses constituting this group isunacceptable and ought to be modified; but the experiment does notdesignate which one should be changed.


Implications: When Experiment contradict with thetheory

1 To protect the fundamental hypotheses by complicating thesituation, suggesting various causes of error, perhaps in theexperimental setup or among the auxiliary hypotheses. Thus theapparent refutation may be deflected or changes are made in otherplaces.

2 To challenge some of the components that are fundamental to thesystem. It does not matter, so far as logical analysis is concerned,whether the choice is made on the basis of the psychology ortemperament of the scientist, or on the basis of some methodology(such as Popper’s exhortation to boldness).

3 There is no guarantee of success, as Duhem pointed out (followedby Popper). Furthermore Duhem conceded that each of the tworesponses described above may permit the respective scientists tobe equally satisfied at the end of the day, just provided that theadjustments appear to work.


Discovery of Neptune

1 Nineteenth century observations of the motion of the planetUranus indicated that its orbit departed considerably from thatpredicted on the basis of Newton’s gravitational theory.

2 Leverrier, Adams, suggested that there existed a previouslyundetected planet in the vicinity of Uranus.

3 The attraction between the conjectured planet and Uranus was toaccount for the latter’s departure from its initially predicted orbit.


References

Karl R. Popper(1963]

Conjuctures and Refutations. 3rd edition (revised), 1969.

Routledge and Kegan Paul

Karl Popper

The Logic of Scientific Discovery

Basic Books Inc. New York

James Ladyman (2002)

Understanding Philosophy of Science

Routledge Publishers, pp 77—91

Pierre Duhem(1954)

The Aim and Structure of Physical Theory

trans. by Philip P. Wiener (Princeton: Princeton University Press, 1991), p.190. Copyright 1954 by Princeton University Press


References

1 http://reasonpapers.com/pdf/24/rp_24_1.pdf

2 http://faculty.washington.edu/lynnhank/Popper-1.pdf

3


http://reasonpapers.com/pdf/24/rp_24_1.pdf

http://faculty.washington.edu/lynnhank/Popper-1.pdf

The End


popper falsification

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