Thomas Kuhn and Karl Popper

1. Thomas Kuhn and Karl Popper 2002/10/18

2. Thomas Kuhn and Karl Popper • Thomas Kuhn (1922-1996) was professor emeritus of linguistics and philosophy at the Massachusetts Institute of Technology. His books includes The structure of scientific revolutions and The Copernican revolutions. • Karl Popper (1902-1994) was professor emeritus of Logic and Scientific Method at the London School of Economics and Political Sciences from 1969 until his death in 1994. Among his works are The logic of Scientific Discovery, The Open Society and its Enemies, and Conjectures and Refutations.

3. 科學 • 科學研究是否是一種理性的活動？ • 科學研究到底是否為探求知識的最佳典範？

4. 科學是自由、理性、民主？ • 我們常被教導一個觀念：科學家便是不斷經由觀察及思考建立具創造性的假說，再經由嚴謹之實驗產生新的發現及發明。 • 但當我們觀察科學界實際運作，卻會有些不同之看法，為什麼？

5. 西方科學哲學的演化 • 實證主義 • 實在論 • 建構實在論

6. 科學哲學之演變 • 近四百年來，西方科學之發展，是以素樸實證主義或邏輯實證論為基礎發展。 • 卡爾波柏(Karl Popper) 提出進化認識論以conjecture-refutation說明科學之原則，也可稱為後實證主義。此後實證主義經由拉卡托斯(Imre Lakatos)精緻化。 • 在李維史陀(Claude Levi-Strass) 及皮亞傑 (Jean Piaget)之結構主義之後，自然科學和社會科學之哲學漸趨不同。 • 其他社會科學中哲學包括胡塞爾 (Edmund G.A. Husserl)之現象學，哈柏瑪斯(Jurgen Habermas)的知識論，及傅科 (Michel Foucault)的後結構主義。 • 相對而言，孔恩 (Thomas Kuhn)是科學史家，對科學之本體或方法論並無特定看法。其他如費耶本德(Paul Feyerabend)之科學無政府主義及勞登(Larry Laudan)之研究傳統也是科學史家。 • 為什麼Thomas Kuhn and Karl Popper常常相對而提？

7. 科學的理路 • Two books have been particularly influential in contemporary philosophy of science: Karl Popper’s Logic of Science Discovery, and Thomas Kuhn’s Structure of Scientific Revolutions. Both agree upon the importance of revolutions in the science, but differ about the role of criticism in its revolutionary growth.

8. Conjectures and Refutations • My hope to solve the quarrel between the classical empiricism of Bacon, Locke, Berkeley, Hume, and Mill and the classical rationalism or intellectualism of Descartes, Spinoza, and Leibniz. • Neither observation nor reason can be described as a source of knowledge. • Karl Popper

9. Science and Pseudo-science • Astrology, Marxist historiography, and psychoanalysis were usually labeled as “pseudoscience.” • The criteria to to distinguish non-science from science: (1) making statements sufficiently vague that they [astronomers] can explain away anything that have been a refutation of the theory.=> destroy the testability of science (2) The way pseudoscience practitioners explained failure is different. [astronomer and astrologer] => If an astronomer’s prediction failed and his calculation checked, he could hope to set the situation right. (Popper) • Thomas Kuhn called it the differences between “non-science and “normal science”

10. Conjecture and Refutation • A simple theme in “Conjectures and Refutations” --> we can learn from our mistakes. • A scientist, whether theorist or experimenter, puts forward statements, or systems, and tests them step by step. In the field of the empirical sciences, he constructs hypothesis, or systems of theories, and tests them against experience by observation and experiment. • Theory --> test --> True or New theory Karl Popper

11. Development of science • 科學的進步基本上是按照「猜測」及「反駁」(conjecture and refutation)的基線發展，而科學中的民主才因此得到保證。 - Karl Popper • Knowledge and ignorance: We can learn from our mistakes --> All our knowledge grows only through the correcting of our mistakes. - Karl Popper

12. Conjecture and Refutation • Karl: A scientist, whether theorist or experimenter, puts forward statements, or systems, and tests them step by step. • Karl: In the field of the empirical sciences, he constructs hypothesis, or systems of theories, and tests them against experience by observation and experiment. • Theory --> test --> True or New theory

13. Karl Popper:Negation Statements • Karl: A theory is scientific if and only if observation statements-particularly the negation of singular existential statements-can be logically deduced.

14. Karl Popper:Negation Statements • Karl stated: falsification or refutation happens when a theory fails in an attempted application, and these are the first of a series of related locutions • In empirical science, all experiments can be challenged either as to the irrelevance or their accuracy. Sir Karl in “Logic of Science Discovery”--> in point of fact, no conclusive disproof of a theory can ever be produced. Statements like these display one more parallel between Popper and Kuhn.

15. Normal Science • 科學家並不是忙於測驗和反駁已經存在的假設，以便建立新的、有更普遍正確性的假設。 • 他們理所當然的認為現有的理論和方法是正確的，並且把它們用於自己的專業目的， 這些目的常常不是發現新理論而是解決具體問題。例如：化合物的分解等。 — Thomas kuhn

16. Normal Sciences: Puzzle-solving • Thomas: …, On the contrary, when engaged with a “normal” science problem, the scientist must premise current theory as the rules of his game. His object is to solve a puzzle, preferably one at which others have failed, and current theory is required to define the puzzle and to guarantee that, at given sufficient brilliance, it can be solved. • Thomas: ‘normal science’ or ‘normal research’ accounts for the majority of the work done in basic science.

17. Kuhn’s view of science • 科學認識的發展過程，是把原有的理論吸收到範圍更大內容更多的理論之中。科學有如寄居蟹，定期脫掉一層殼，然後換上一層更大的殼。事實可能是事實，但是知識的主要工具是模式。模式把諸多的事實結合在一個結構裡。設想一片有些散亂黑點的平面，看不出圖案，但再多增加些點，便有人能提出模式，預測其他更多點之位置。 • —Thomas Kuhn 之說法

18. Normal Science and Extraordinary Science • Normal science means research firmly based upon one or more past scientific achievements, achievements that particular scientific community acknowledges for a time as supplying the foundation for its further practice. • Though testing of the basic commitments occurs only in “extraordinary” science, it is the normal science that disclose both the points to test and the manner of testing.

19. The Nature of Normal Science • The nature of normal science: paradigm (典範). 某一科學研究工作的科學社群(scientific community)所共同接受的基本觀點和研究方法，科學家遵照典範的規定來解決難題(puzzle)。有些難題無法解決稱之為異例(anomaly)。異例一般歸之於科學家能力或努力不夠，不會危及典範。只有在異例明顯令人懷疑典範，或大量異例產生而開始產生種種爭論 ==> Crisis ==> new paradigm ==> another new normal scienceThomas Kuhn

20. The route to Normal Science • 百家爭鳴==> uniform ==> paradigm • At various times all these schools made significant contributions to the body of concepts, phenomena, and techniques from which Newton drew the first uniformly accepted paradigm for physical optics. Those men were scientists. Yet anyone examining a survey of physical optics before Newton may well conclude that, though the field’s practitioners were scientists, the net result of their activity was something less than science. • But though this sort of fact-collecting has been essential to the origin of many significant science. One somehow hesitate to call the literature that results scientific. Thomas Kuhn

21. The Nature and Necessity of Scientific Revolutions • Sometimes, the new theories make the old theory “restricted.” A best example is that Einstein’s theory can be used to show that predictions from Newton’s equations will be as good as our measuring instruments in all applications that satisfy a small number of restrictive conditions. • New and old paradigms differ in more than one substance, for they are directed not only to nature but also back upon the science produce them. They are the source of the methods, problem-field, and standards of solution accepted by any mature scientific community at any given time. Thomas Kuhn

22. The Nature and Necessity of Scientific Revolutions • There are, in principle, only three types of phenomena about which a new theory might be developed. The first consists of phenomena already well explained by existing paradigms, and these seldom provide either motive or point of departure for theory construction. When they do, the theories that result are seldom accepted. A second class of phenomena consists of those whose nature is indicated by existing paradigms but whose details can be understood only through further theory articulation. These are the phenomena to which scientist direct their research much of the time, but that research aims at the articulation of existing paradigms rather than at the invention of new ones. Only when these attempts at articulation fail to do scientists encounter the third type of phenomena, the recognized anomalies whose characteristic feature is their stubborn refusal to be assimilated to existing paradigms. This type alone gives rise to new theories.Thomas Kuhn

23. Differences in Concepts of Sciencebetween Kuhn and Popper • Thomas: …, On the contrary, when engaged with a “normal” science problem, the scientist must premise current theory as the rules of his game. His object is to solve a puzzle, preferably one at which others have failed, and current theory is required to define the puzzle and to guarantee that, at given sufficient brilliance, it can be solved. • Thomas: ‘normal science’ or ‘normal research’ accounts for the majority of the work done in basic science.

24. Differences in Concepts of Sciencebetween Kuhn and Popper • Neither science nor the development of knowledge is likely to be understood if research is viewed exclusively through the revolutions it occasionally produces. • Though testing of the basic commitments occurs only in “extraordinary” science, it is the normal science that disclose both the points to test and the manner of testing.

25. Differences in Concepts of Sciencebetween Kuhn and Popper • No puzzle-solving enterprise can exist unless its practitioners share criteria which, for for that group and for that time, determine when a particular puzzle has been solved. The same criteria necessarily determine failure to achieve a solution. • Failure of a theory to pass a test is not usually viewed that way. Only the practitioner is blamed, not the tools. But under the special circumstances which induce a crisis in the profession (e.g. gross failure, or repeatedly failure by the most brilliant professionals) the group’s opinion may change. • Thomas Kuhn

26. Differences in Concepts of Sciencebetween Kuhn and Popper: What is mistake? • A simple theme in “Conjectures and Refutations” --> we can learn from our mistakes. • In most of the cases, a person is not sure a mistake has been made, at least not a mistake to learn from --> for example, addition of EGF to serum-starved non-confluent cells caused the cell death --> apoptosis?

27. What is mistake? • The individual can learn learn from his mistakes only because the group whose practice embodies these rules can isolate the individual’s failure in applying them. --> for example, invert gently during mini-prep of plasmid DNA. • In karl’s statement, a mistake infects the entire system and can only be corrected only by replacing them. ==> we only deal with normal problem in the systems.

28. My comments • Example for Kuhn’s argument: PCR --> ligation fail ==> crisis ==> additional A at the end ===>TA cloning kit. • In addition, on some occasions, tests are not requisite to the revolutions through which science advances. For example, Ptolemics were placed before they had in fact be tested.

29. Normal Science and its Danger By Karl Popper • I think that the distinction between “Normal Science” and “extraordinary Science”is perhaps not quite as sharp as Kuhn makes it; yet I am ready to admit that I have at best only dimly aware of this distinction. • The “normal” scientist, in my view, has been taught badly. I believe, and so do many others, that all teaching on the university level should be training and encouragement in critical thinking. The “normal” scientist, as described by Kuhn, has been badly taught.

30. Normal Science, Scientific Revolutions and the History of Science by Pearce Williams • Kuhn and Popper base their systems on (in Kuhn’s case) what scientists do(with no hard evidence that they do science this way) or (in Popper’s case) on what they oughtto do (with very few examples to persuade us that is right). • Both kuhn and Popper really basetheir views of the structure of science on the history of science and the main point of my remarks here is that the history of science cannot bear such a load at this time.

31. 拉卡拖斯之精緻否定論 • 任何理論都不是孤立存在，而是一系列相互聯繫，且具有嚴密內在結構的理論系統。他提出sophisticated falsification。他主張以﹝理論系列﹞的概念取代﹝理論﹞。 • 區別科學與非科學應不是孤立理論之檢驗而是一系列理論之能否進化。一個後續理論在前理論中作某些輔助修正而消化原理論中之異例(anomaly)，同時後續理論能預估﹝新奇事實﹞。則這種理論調整過程稱為進化。

32. Understand the History of Science • Fundamental issues on which Kuhn and Popper agreed: Analysis of the development of scientific knowledge must take account of the way science has actually been practiced.

33. 科學共同體 • 科學是一個社會意義上的共同體的工作， 在某一特定領域內的科學形成一個封閉的共 同體，他們採用特別適用於其他任務的方法 和工具來研究範圍確定的問題。 他們對問題的定義和所用的研究方法適從理論技術的傳統 中獲得的。而且可以靠長期的訓練獲得這些東西，包括思想灌輸。 --- Michael Polanyi

34. 科學共同體、Normal Science • 以上暗示： (1)科學和外部的社會影響是有相當隔絕的。例如：近代物理學家在蘇聯和其他國家的物理學家處理科學的態度是一致的。 (2)科學家考慮的問題以及處理這些問題的方式由他們自己的傳統決定的。成熟的科學家擁護這些傳統並傳遞給下一代。 • 科學共同體由此看來似乎是一個封閉的群體，它如何 (a)產生違反舊傳統的新發現。 (b)和外部社會相互產生作用。

35. 科學共同體之特性 • 為回答此問題，須先了解科學共同體之特性。 • 在科學領域中普遍存在「科學發現的優先權」，每一個科學家都希望在論文記錄他的優先發現。科學和藝術工作不同。藝術的創作包含有強烈個人色彩，具有不可取代性。 • 而科學的工作則為可“重覆”且必須可“重覆”， 所以優先發現權是首要目標。 • 所以科學論文形成科學界主要之中介。

36. 科學共同體特性 • 科學共同體 (Scientific Community) ◆科學家之間的交流，最主要是以科學論文做為中介。所以要了解科學共同體，必須以科學論文數量的成長，及科學論文對於科學家產生的社會功能做為研究基礎。 ◆科學論文的發表是為了知識和信息交流！/？ ◆科學論文的發表呈爆炸指數增長現象！/？ ◆科學家是有血有肉，為名為利的社會存在者 ◆科學家發表論文是一種社會手段，發表論文的原動力是為了建立和保持 "知識的產權" ___ Little Science, Big Science Derek J. De Solla Price

37. 科學家及科學共同體 • 在科學共同體中，科學家可以獲得 (1)建立自己優先權及地位威望。 (2)接觸有威望之領袖而抬高自己的身價。 (3)透過和其他科學家的接觸而獲得無價之優越及好處。

38. 科學共同體之分層結構 • 科學共同體並非如一般人想像是一個崇尚科學與真理的人群組合，其中不會有階級的分化。事實上，科學共同體內部社會之分層現象以相當顯著的方式存在著。—科學社會學 李英明

39. 社會分層系統之必要性 在一個社會中分層系統的基本功能是可以整合社會，而事實上，一個社會分層系統的存在也意謂著社會有某些評價不同社會等級的共同標 準。此外，社會分層系統也有某種工具性或調整性功能，它可以提供不同的誘因，讓不同的角色能夠實現。 — Social Stratification Bernarol Barber

40. 社會階層化 國家或有組織的社會，起源於人類的需求。 沒有一個人是自給自足，我們都有許多需要- ----我們大家並不完全一樣， 我們當中天生各有差異適用於各種不同的職業。 —理想國‧柏拉圖 自給自足的人，必是一個禽獸，或是一個神 ---------大而完整，且又能充份自給自足的社區， 便成為國家。 —亞理斯多德 同樣的對待不平等的，必產生不平等。 —Laws‧柏拉圖

41. 科學界的分層系統 • 科學界的分層系統 (1)愛因斯坦，蒲朗克 (2)諾貝爾獎得主 (3)地位顯赫，有權力可控制設備及資源的人 (4)主要大學的人、政府實驗室領導人、科學雜誌編輯，科學協會領導人。 • 所以科學之分層是以「聲望」做決定，而聲望則以「對科學知識的貢獻」為主要決定因子。其他則以對[科學群體]做出貢獻」做為分層參考。 — Social Stratification in Science Jonathan Cole and Stephen Cole

42. 如何防止科學分層之弊端 • 科學共同體之「權威」必然會對「經費」、「職業發展」上產生影響力。此影響力有其一定程度負面作用，但最主要有兩個因子可減少其弊端： (1)科學的「普遍信念」： (a)評價科學以科學研究的品質及對科學知識發展的貢獻而定的。 (b)每個科學家可以在自己的崗位上對科學的進步做出貢獻。它告訴科學家儘管沒有獎勵、職位，但它們的工作是科學共同體所必需的。這個信念告訴科學家，整個科學共同體猶如一個生理有機體。 (2)科學共同體內，權力組織是相當分散的。— Social Stratification of Science

43. 科學分層 • 科學共同體的不同成員皆曾抱怨科學資源的不公平及權力集中的現象。但在其中 〞富有者〞和〞貧窮者〞之衝突卻較其它社會為少。 — Social Stratification of Science

44. 普遍科學共識產生科學分層 • 科學「共識」的產生，是科學精英權威的行使。例如一個新的理念之產生，必然會受到許多評價決定，應否成為一個共識或遭到揚棄。而科學精英的評價必然扮演關鍵的角色。科學如果沒有共識，科學家有可能各說各話，彼此之間莫衷一是，而科學可能因此而喪失累積性。拋棄科學中的權威原則將消滅某種得以放棄某些差勁的科學成果之合理基礎。 • 當然有時，會因為如此而使某些新的理念被拒捕或忽略，但是科學中維持共識的正面作用，遠比偶然失敗所導致的負面結果來得大。如果科學家太容易去接受一個非正統的理論，整個科學的知識結構將變得一片混亂。— Jonathan Cole and Stephen Cole

45. 普遍科學共識？ • Cole:論「普遍主義」(Universalism) 科學有一個傾向「普遍主義」，從一個具有普遍性的參考架構的基礎上，去評斷個別科學家或科學研究。但什麼是「高品質的科學成果」仍會有衝突的看法。所以科學共同體是如何對「高品質的科學成果」形成相當高水平的共識？ • Thomas Kuhn: 科學真理只是暫時性的，在科學共同體中，是當時科學家的共識決定真理，而不是真理決定共識。世界上沒有永恆的真理存在，有的只是關於「世界應該如何被評價」的一系列不斷改變的共識。

46. 科學共識及民主多元？ • Karl R. Popper and J. Agaisi 認為： 不能高估「科學權威」之作用。科學的進步基本上是按照「猜測」及「反駁」(conjecture and refutation)的基線發展，而科學中的民主才因此得到保證。 • Feyerabend 也認為：科學在事實上並沒有固定和普遍的方法論規可以遵循。人們儘可能從多元主義角度使用一切思維和方法理解自然。

47. 科學真理？ • 新的科學真理嬴得立足地，並非因為說服了敵對者相信，讓他們看到光明前景，而是敵對者最後凋零殆盡，熟悉新真理的新一代後輩長大成人，新科學真理才因此取得勝利。 —Max Planck

48. 科學區域之發展 • 在科學共同體內，以“聲望”“貢獻”領導科學前進，但科學的前進卻是有區域性，而且漸次的轉換。科學在各不同區域內如何興衰： • 湯淺光前：科學發展之不平衡定律，科學發展之區域性。 • 義大利 1540-1610 • 英國 1660-1730 • 法國 1770-1830 • 德國 1840-1920 • 美國 1920-

49. References 1. “Criticism and the groth of knowledge” edited by Imre Lakatos & Alan Musgrav, 1965, Cambridge University Press. 2. “The structure of scientific revolutions” by Thomas S. kuhn, 1966, The University of Chicago Press. 3. “Conjectures and Refutations” by Karl Popper, 1963, Routledge & Kegan Paul Plc. 4. “Popper Selections” edited by D. Miller, 1985, Princeton University Press. 5. 社會科學的理路 by 黃光國，2002, 心理出版社.