How Does Science Add to Knowledge?

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    • 00:01


    • 00:09

      NARRATOR: We live in a world transformed by modern science.We look to science to cure diseases, fill the futurewith mind-boggling inventions, and keep usfrom destroying the planet.What are these hopes based on?Does science have some remarkable power?

    • 00:32

      NARRATOR [continued]: Is there a scientific method that we can count onto produce miracles?[MUSIC PLAYING]

    • 01:13

      NARRATOR [continued]: [ The Examined Life ]Sir Francis Bacon was a spokespersonfor the scientific revolution.This prominent philosopher of the Renaissance

    • 01:34

      NARRATOR [continued]: rose to the rank of Lord Chancellor of Englandbefore he was convicted of accepting bribes.After a short time in jail, he retiredto write and to conduct scientific experiments.In one book, Bacon imagined an islandhe called the new Atlantis, where people

    • 01:55

      NARRATOR [continued]: had mastered nature through science,and even devised machines like helicopters and submarines.Closer to home, Bacon criticized the schools of his dayfor concentrating on scholarly texts,and he urged people to open their eyes to nature.

    • 02:13

      ACTOR AS SIR FRANCIS BACON: Let usestablish a chaste and lawful marriagebetween Mind and Nature.Knowledge and human power come to the same thing,for nature cannot be commanded except by obeying her.Enough if, from our approaching her with due respect,she condescends to show herself.

    • 02:35

      IAN HACKING: He believed that the constant attention to booklearning was wrong, and he formulated,[Ian Hacking, UNIVERSITY OF TORONTO]I think without fully knowing how his words wouldbe used, this idea that what we must go out and observethe world.The book must be the book of nature,which must teach us everything which is to be learnt about

    • 02:58

      IAN HACKING [continued]: our material life.

    • 03:01

      NARRATOR: Although Bacon put observation of nature first,he also placed a high value on reflection.

    • 03:07

      ACTOR AS SIR FRANCIS BACON: The men of experimentare like the ant, they only collect and use;the reasoners resemble spiders, who make cobwebs outof their own substance.But the bee takes the middle course:it gathers material from the flowersof the garden and the field, but transforms and digests it

    • 03:29

      ACTOR AS SIR FRANCIS BACON [continued]: by a power of its own.

    • 03:32

      NARRATOR: Bacon urged scientists to use a method which he calledinduction-- make a number of observations,look for general patterns, test those patterns,and finally, grasp the underlying laws of nature.In many ways, induction is a thought processwe use every day.

    • 03:53

      ARTHUR FINE: Most of the kinds of conclusions that we come to,most of the practices [Arthur Fine, NORTHWESTERN UNIVERSITY]that are embodied in how we behave--our inductive practices-- are practices thatcome from making particular observationsand some small generalization and then acting on that,or trying it out.

    • 04:09

      SUSAN HAACK: First of all, there'sa bunch of questions about what sorts of inferencesdo scientists make? [Susan Haack, UNIVERSITY OF MIAMI]To which I want to say, well many of the same kindsof inferences that historians make, legal scholars make, youor I make.The same kinds of inferences I make when I ask myself,well, how come when I cooked that dish tonight,

    • 04:33

      SUSAN HAACK [continued]: it was so much better than when I cooked it last week?Was it better tomatoes, or I browned the onions more,or-- what was it?I think a lot of the inferential processes are quite common.

    • 04:47

      NARRATOR: A critical step in scientific inductionis conducting experiments to confirmconnections between events.

    • 04:55

      W.V. QUINE: What we're doing is setting a trap, as best we can,that is to trap nature and get one of her secrets.We're deriving an implication of [W.V. Quine, HARVARDUNIVERSITY] an observable event from the assumptionof another observable event, and at which point

    • 05:17

      W.V. QUINE [continued]: we can set up our experiment, and find out.So there's the trap with which we're hoping to get natureto express herself.

    • 05:30

      NARRATOR: Bacon wrote in an opportune time.Several decades later, scientistswho founded the Royal Society of Londonused his ideas to formulate their goals.

    • 05:41

      PHILIP KITCHER: Bacon's experimental approachesof his own were not remarkably wonderfulor remarkably successful.But he did sort of lay down these [?[Philip Kitcher, UC SAN DIEGO] ?] principles,and the Royal Society adopted the Baconian creed.And it was officially there in the Royal Society's historyfrom the beginning.And so because of this start, this sort of Baconian

    • 06:04

      PHILIP KITCHER [continued]: advertisement, the Royal Society's acceptanceof this idea, inductivism had enormous cachet,I think, through the 18th and 19th centuries,especially in Britain.And that was further reinforced by the apparent great successesof people like Boyle and Hooke and Newton and so forth.

    • 06:25

      PHILIP KITCHER [continued]: It looked as though this was the way to go.

    • 06:29

      NARRATOR: From a modern perspective, though,it is highly debatable whether the scientists of the RoyalSociety practiced induction as uniformly as they believed.How much common ground was there really between Robert Boyle'sdiscovery of how pressure affects the volume of gasesand Isaac Newton's theory of universal gravity?

    • 06:49

      PHILIP KITCHER: You see a differencebetween the kind of mathematical science that Newton is doingand that Descartes was doing before him,and the sort of nitty gritty experimental detail that'stypified by somebody like Boyle.Boyle builds a pump and collects lots and lots of observationson the spring of the air.

    • 07:12

      PHILIP KITCHER [continued]: Newton works out the mathematical problemof how two bodies would interact if therewere an inverse square law of attraction between them.Now Bacon's account seems to work more beautifullyfor the Boylian sciences, the experimental sciences,

    • 07:34

      PHILIP KITCHER [continued]: than it does for the theoretical ones.Although Newton himself, I'm sure,would have said on his deathbed, Ihave followed the true road of Francis Bacon.

    • 07:48

      NARRATOR: Newton did in fact describe his theoryas inferred from the phenomena, basedon observations of falling objects and orbiting planets.And for centuries, most scientists and philosophersagreed.

    • 08:01

      PHILIP KITCHER: During the 18th century,and after the enormous success of Newton's work-- especiallyNewton's mechanics and theory of the universe--there was a sort of official empiricistaccount of how scientific knowledge was developed.We went out, we got observations.And in light of these observations,

    • 08:21

      PHILIP KITCHER [continued]: we were able to arrive by inductive inferencesat generalizations, and we could gradually systematize these.And if we proceeded carefully and deliberately enough,we would arrive at a body of well-grounded knowledge.

    • 08:39

      IAN HACKING: The history of philosophies of scienceis-- it's an odd interaction between whatthe philosophers say and how the scientists present themselvesto themselves.I mean, so that the scientists in the 17th century--most of them, certainly the ones in the English-speaking world--

    • 09:03

      IAN HACKING [continued]: presented themselves as if they were doing what Bacon wasdoing, even when they plainly, now historians will say,weren't.Newton wasn't doing that, for goodness sakes.

    • 09:15

      NARRATOR: But if scientists don't derive their theoriesfrom observation of nature, how do they come up with them?One alternative was proposed by 18th century philosopher,Immanuel Kant-- through pure reason.

    • 09:30

      ACTOR AS IMMANUEL KANT: Reason must approach naturein order to be taught by it.It must not, however, do so in the character of a pupil wholistens to everything that the teacher chooses to say,but of an appointed judge who compelsthe witnesses to answer questions whichhe has himself formulated.

    • 09:50

      STEPHEN TOULMIN: Now this is a very striking imagebecause what it makes clear is that every scientificinvestigation is in the nature of an interrogation.[Stephen Toulmin, UNIVERSITY OF SOUTHERN CALIFORNIA]And that it is we who have framedthe questions that our observations of naturehave to be used to give answers to.

    • 10:11

      STEPHEN TOULMIN [continued]: It isn't that nature forces on us thequestions that we have to get the answers to.

    • 10:19

      NARRATOR: Despite occasional dissenting voicessuch as Kant's, inductivism remainedthe dominant view of how science works until the 20th century.Ironically, it came under attack partly due to a new conceptof gravity.In 1915, in his general theory of relativity,Albert Einstein proposed an entirely different approach

    • 10:42

      NARRATOR [continued]: from Newton's.

    • 10:44

      QUENTIN SMITH: We would say that the sun sendsoff [Quentin Smith, WESTERN MICHIGAN UNIVERSITY]infinitely fast forces to the different planets,and these forces forced the planetsto go in orbit around the sun.Whereas the space itself, for Newton, is completely flatand has no effect on it whatsoever.

    • 11:06

      QUENTIN SMITH [continued]: Whereas for Einstein, there are no forces going back and forthbetween the planets and the sun.But space is not completely flat.Space has been all curved up around the sun,and the planets are just travelling a free orbit throughthis curved space.And for them, this is the straightest passfor the planets travelling through this curved space.

    • 11:27

      NARRATOR: Also in the early 20th century,quantum mechanics suggested that Newton's laws of motiondon't apply at the atomic and subatomic level.These events prompted philosopher, Karl Popper,to put forward a radically new view of how science works.

    • 11:45

      ACTOR AS KARL POPPER: I accept that scientific knowledgeis essentially conjecture or hypothetical.The great scientists such as Galileo, Kepler, Newton,Einstein, and Bohr, represent to me a simple but impressive ideaof science.These are men of bold ideas.

    • 12:07

      ACTOR AS KARL POPPER [continued]: But highly critical of their own ideas,they tried to find whether their ideas areright by trying to find whether they are not perhaps wrong.They work with bold conjectures and severe attemptsat refuting their own conjectures.

    • 12:27

      NARRATOR: Inductivism agrees with the empiricist viewthat all knowledge must come from experience.Popper's position, by contrast, parallels the rationalist viewthat our deepest insights come from pure reason, notexperience.

    • 12:44

      IAN HACKING: Popper really did kind of crystallize--just as Bacon crystallized-- Popper reallydid crystallize another conception of scienceas being essentially theoretical.There had been many, many-- read, many again--immediate reasons for this.

    • 13:05

      IAN HACKING [continued]: I mean, Popper was personally-- but the worldwas collectively-- bowled over by the way in which Einsteinhad transformed our conceptions of space and time.And perhaps even more dramatically,the way in which the quantum mechanics

    • 13:26

      IAN HACKING [continued]: had transformed our conceptions of underlying causality.And Popper grew up in-- I mean, his youthwas formed in a world where Einstein and Planck, and thenHeisenberg and Bohr, were household names.And these were people who did their work, he thought,

    • 13:49

      IAN HACKING [continued]: in the head.It was the theory which transformed.

    • 13:53

      NARRATOR: Where do new ideas and theories come from?

    • 13:55

      ACTOR AS KARL POPPER: My view maybe expressed by saying that every discover containsan irrational element or a creative intuition.In a similar way, Einstein speaksof the search for those highly universal lawsfrom which a picture of the worldcan be obtained by pure deduction.

    • 14:16

      ACTOR AS KARL POPPER [continued]: There is no logical path, he says, leading to these laws.They can only be reached by intuitionbased upon something like an intellectual loveof the objects of experience.

    • 14:31

      NARRATOR: In an inductivist view of science,tests are supposed to confirm theories.Popper maintained instead that the role of testsis to refute or falsify theories.

    • 14:44

      ACTOR AS KARL POPPER: The rationality of sciencelies not in its habit of appealingto empirical evidence in support of its dogmas,but solely in the critical approach.Science has nothing to do with the quest for certaintyor probability or reliability.We are not interested in establishingscientific theories as secure or certain or probable.

    • 15:09

      ACTOR AS KARL POPPER [continued]: Conscious of our fallibility, we areinterested only in criticizing them and testing them,in the hope of finding out where we are mistaken,of learning from our mistakes.And if we are lucky, of proceeding to better theories.

    • 15:28

      PHILIP KITCHER: So science, he says,makes fallible conjectures-- the bolder the better.We like them bold because then theyhave the promise of giving us a lot of informationabout the world.But of course, the bolder they are, the less likelythey are to be true.So we aim at bold conjectures, expectingthat they will be false.

    • 15:49

      PHILIP KITCHER [continued]: We try very hard, says Popper-- thisis where it starts to get a bit unrealistic-- we all try veryhard to falsify our conjectures, but if theyprove not to be falsified by our experiences,then we "tentatively" accept them.

    • 16:06

      IAN HACKING: What are the criteriafor bold guesses, as opposed to talking through your hat?The bold guess which is testable is the one which has merit.And a bold guess which you cannot test against anythinghas no merit.So being falsifiable, being testable,becomes the touchstone of being scientific for Popper.

    • 16:32

      NARRATOR: Inductivists sometimes envision scienceas one vast structure.We build it level by level, setting new knowledgeon top of the old.For Popper, perceiving all theories as falliblealtered, but did not destroy, this vision.

    • 16:49

      W.V. QUINE: Some of our generalizationsturn out to be more stubborn and enduring than others,therefore, we feel more dependable.So we're pitting what seems to be the more conjectural,the less certain, on what we feel to be more certain,and the whole better is simply afloat that way.

    • 17:13

      W.V. QUINE [continued]: Or a better analogy than afloat is KarlPopper's-- the [INAUDIBLE] Karl Popper--figured that science is a great structure built on a bottomlessswamp on piles that are driven vertically-- very long,

    • 17:36

      W.V. QUINE [continued]: long sturdy piles going into the swamp, bottomless swamp,but driven far down.And many of them.And that's what keeps our science on a pretty even keel.And we keep fixing things up and restoring the balance when

    • 17:57

      W.V. QUINE [continued]: we find that it needs it.It's the way we get by without absolute certainty.

    • 18:07

      NARRATOR: Philosophers have challenged Popper's viewof science on various grounds.Most simply, the same question that Popperposed against inductivism can be posed against his emphasison falsification.Does science really work that way?

    • 18:24

      PHILIP KITCHER: How many scientistsdoes one know who actually go out deliberately tryingto falsify their hypothesis?And then, what's this sort of tentative acceptance stuff?And we rely on science in all kinds of contexts--when human lives are at stake.I mean, can our acceptance really be that tentative?

    • 18:45

      NARRATOR: Among Popper's critics,one offered a broad new perspective of his own.Thomas Kuhn says of Popper--

    • 18:53

      ACTOR AS THOMAS KUHN: He is convincedthat growth occurs not primarily by accretion,but by the revolutionary overthrowof an accepted theory, and its replacement by a better one.Episodes like these are very rare in the developmentof science.I suggest that Sir Karl has characterizedthe entire scientific enterprise in terms

    • 19:15

      ACTOR AS THOMAS KUHN [continued]: that apply only to its occasional revolutionary parts.

    • 19:21

      NARRATOR: Thomas Kuhn brought historical perspectiveto the question of how science works.Through detailed study of various sciencesin different eras, Kuhn detected a striking pattern--brief periods of revolution are setagainst a background of longer, calmer periods, whichKuhn calls normal science.

    • 19:42

      NARRATOR [continued]: In a period of normal science, a community of scientistsworks within what Kuhn calls a paradigm.

    • 19:49

      IAN HACKING: The paradigm refers to two different things,one of which is the particular achievement of solvinga certain set of problems, which then becomesa model of how to try to solve problemsin that field in the future.And this paradigm, this established achievement and set

    • 20:13

      IAN HACKING [continued]: of methods, becomes the model for scientific workin that field in the immediate future.

    • 20:21

      NARRATOR: For instance, Newton's mechanicsand Einstein's theories of relativityserved as paradigms in physics during different eras.From antiquity until Copernicus, Aristotle's theorythat the sun and other planets revolve around Earthprovided the paradigm for astronomy.

    • 20:41

      NARRATOR [continued]: Every paradigm has some point in timewhen it starts to be accepted.

    • 20:47

      ACTOR AS THOMAS KUHN: The success of a paradigmis, at the start, largely a promise of success discoverablein selected and still incomplete examples.Normal science consists in the actualizationof that promise, an actualization achievedby extending knowledge of those factsthat the paradigm displays as particularly revealing,

    • 21:10

      ACTOR AS THOMAS KUHN [continued]: by increasing the extent of the match between those factsand the paradigm's predictions, and by furtheringthe articulation of the paradigm itself.Few people who are not actually practitionersof a mature science realize how muchmop-up work of this sort a paradigm leaves to be done,or quite how fascinating such work

    • 21:31

      ACTOR AS THOMAS KUHN [continued]: can prove in the executioner.Mopping-up operations are what engagemost scientists throughout most of their careers.

    • 21:39

      NARRATOR: Popper and most inductivistssaw scientists as pioneers.Kuhn sees them, in periods of normal science,as ordinary people, puzzle solverswho work strictly within the confines of a paradigm.When they come upon a problem that doesn't fit the paradigm,they set it aside.But gradually, such problems mount,

    • 21:59

      NARRATOR [continued]: and a period of revolutionary science begins.

    • 22:03

      IAN HACKING: People bash their heads against a wall--seems impossible to resolve a certain group of difficulties.And at that point, he says, that branch of sciencewill pass from normal science into a state of crisis,where everybody's attention is focused on these anomalies

    • 22:25

      IAN HACKING [continued]: and can't figure out what's going on.And then, a new idea will appear.Which is somehow in the same field of inquiry,but totally changes the ways in which phenomena are described,and moreover, enables one to solve some of those-- precisely

    • 22:49

      IAN HACKING [continued]: those-- outstanding problems.

    • 22:52

      NARRATOR: As this new paradigm becomes established,normal science resumes.

    • 22:58

      PHILIP KITCHER: As one person put it-- Sylvain Bromberger,nice remark-- "science is a seriesof exercises in imitation," that's the normal sciencestuff, "punctuated by changes in fashion,"those are the revolutions.

    • 23:15

      NARRATOR: Like Popper, Kuhn argues that scientists almostnever follow Bacon's suggestion and simply observe nature.Rather, a paradigm influences what they observe,and how they interpret it.Kuhn also agrees with Popper that induction does notproperly describe how scientists arrive at theories.

    • 23:36

      ACTOR AS THOMAS KUHN: Neither Sir Karl nor Iis an inductivist.We do not believe that there are rulesfor inducing correct theories from facts,or even that theories, correct or incorrect,are induced at all.Instead, we view them as imaginative posits,invented in one piece for application to nature.

    • 23:57

      NARRATOR: In perhaps his most controversial departurefrom inductivism, Kuhn challenged the ideathat science progresses cumulativelywith new ideas building upon the old.

    • 24:09

      PHILIP KITCHER: Kuhn says the relationbetween the new paradigm and the old paradigmisn't that this one sort of sits neatly on top of that.It's rather, this is a completely different framework.It's got new concepts, new ways of seeingthe world, new methods, all kinds of things.And so in a very suggestive term,

    • 24:30

      PHILIP KITCHER [continued]: he claims the paradigms are incommensurable with oneanother.

    • 24:35

      ACTOR AS THOMAS KUHN: Led by a new paradigm,scientists adopt new instruments and look in new places.Even more important, during revolutions,scientists see new and different thingswhen looking with familiar instruments in different placesthey have looked before.It is rather as if the professional community havebeen suddenly transported to another planet,

    • 24:57

      ACTOR AS THOMAS KUHN [continued]: where familiar objects are seen in a different lightand are joined by unfamiliar ones, as well.

    • 25:04

      NARRATOR: Some have seen Kuhn's ideasabout paradigms as an argument against progress.Kuhn himself argued that science does make progress.New paradigms can be judged superior to oldby standards such as scope and simplicity.But after Kuhn, it is much harderto picture science as one great structure

    • 25:25

      NARRATOR [continued]: of timeless knowledge.

    • 25:27

      IAN HACKING: I think against the background of itall, the deepest transition that hemade was to think of rationality itselfas being something which is historically conditioned.And I think that that change has in some waypermeated a lot of modern culture.

    • 25:50

      NARRATOR: Given the striking differences among evena few views, can any satisfactory answersbe given to the questions-- how does science work?And is there a scientific method?

    • 26:04

      PHILIP KITCHER: One of the impulsesthat has come out of the responses to Kuhn, I think,has been the recognition of a great deal of diversityamong the sciences.So perhaps it's the wrong questionto say, well look, how does science work?Perhaps we should ask ourselves instead, well,how does molecular genetics in the second half

    • 26:28

      PHILIP KITCHER [continued]: of the 20th century work?

    • 26:31

      STEPHEN TOULMIN: I think we do rob ourselves--we do impoverish our understanding-- if we insiston only one kind of explanation, only one kind of methodbeing truly scientific.And we enrich our ability for making the world intelligibleto ourselves if we're prepared to hang a bit looser

    • 26:52

      STEPHEN TOULMIN [continued]: and to accept the legitimacy of all kinds of explanations.

    • 26:58

      IAN HACKING: And of course, it's not the casethat science is all theory, or science is all experiment.Science is a intimate interactionbetween what we do with our handsand what we do in our heads, and whatwe do by talking to each other.

    • 27:13

      PHILIP KITCHER: And it may be at the end of the daythat we have a picture of the sciences which doesn't see themin the same sort of total and monolithic way,but as a bunch of enterprises with some common featuresamong them.That all of which-- or perhaps various of themto different degrees and in different respects--are good at giving us insight into the way the world works,

    • 27:38

      PHILIP KITCHER [continued]: but that don't have sort of some shared featurethat we can hail as "the scientific method."[MUSIC PLAYING]

How Does Science Add to Knowledge?

View Segments Segment :


An assembly of philosophers and scientists discuss the nature of science and experimentation. They discuss how we ask scientific questions and how science typically advances through time.

How Does Science Add to Knowledge?

An assembly of philosophers and scientists discuss the nature of science and experimentation. They discuss how we ask scientific questions and how science typically advances through time.

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