HPS 1653 / PHIL 1610 Introduction to the Philosophy of Science

Transcription

1 HPS 1653 / PHIL 1610 Introduction to the Philosophy of Science Kuhn I: Normal Science Adam Caulton adam.caulton@gmail.com Monday 22 September 2014

2 Kuhn Thomas S. Kuhn ( ) Kuhn, The Structure of Scientific Revolutions (2012 [1962]) Chalmers, WITTCS?, Ch. 8 Godfrey-Smith, T&R, Chs. 5 & 6

3 Kuhn Physicist, historian & philosopher Structure originally printed as an essay in The International Encyclopaedia of Unified Science, 1962 (volume II of Foundations of the Unity of Science), published by ex-members of the Vienna Circle. PGS: Structure as a Trojan horse?

4 The structure of Structure Chapters I-II: Emergence of normal science Chapters III-V: Paradigms & puzzle solving Chapters VI-VIII: Anomalies & crises Chapters IX-X: Revolution, worldview & incommensurability Chapters XI-XIII: Post-revolution & progress N.B. The 50th anniversary edition contains an introductory essay by Ian Hacking. Use it!

5 A role for history Previous philosophers of science had emphasized a sharp separation between history of science and the philosophical theory of science. (Contexts of discovery and justification again) Their methodology: formulate a theory of science in particular, the justification of scientific claims regardless of what scientists actually do or have done. Kuhn s methodology: assume that science, as it is, is already successful, or has successful elements, give an account of how that success is achieved. This entails an indispensable role for history of science in the philosophy of science. Elements of scientific practice that are key to science s success had been missed by ahistorical accounts (inductivism, hypothetico-deductivism, falsificationism).

6 A role for history To get a realistic picture of science, we need to go further than the histories created for the purposed of persuasion and pedagogy. [A] concept of science drawn from them is no more likely to fit the enterprise that produced them than an image of a national culture drawn from a tourist brochure or a language text. (p. 1) Against Whiggish history. Against (the illusion of) inevitability.

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8 HPS 1653 / PHIL 1610 Lecture 8

9 The treasure chest picture of science The old historiographic orthodoxy. The historian of science s two main tasks: 1. To determine by whom and when each contemporary scientific fact, law & theory was discovered or invented. 2. To describe & explain the congeries of error, myth, and superstition that inhibited the more rapid accumulation of the constituents of the modern science text. An explanatory asymmetry: success is explained by epistemic factors; failure is explained by social factors. A dilemma: are out-of-date theories (e.g. Aristotelian dynamics, vitalism, phlogiston,... ) science or myth? If myth: contemporary science is generated by the same methods, so how is contemporary science not also myth? If science: then science has included bodies of belief quite incompatible with the ones we hold today. (p. 3)

10 The historiographic revolution Rather than seeking the permanent contributions of an older science to our present vantage, [we] attempt to display the historical integrity of that science in its own time. (p. 3) E.g. Not: What relation did Galileo s views have to modern science? But rather: What relation did Galileo s views have to his contemporaries? Or: What made Galilean dynamics more plausible than Aristotelian dynamics to his contemporaries?

11 The historiographic revolution: two key morals 1. Under-determination of theory by data & method: The insufficiency of methodological directives... to dictate a unique substantive conclusion to many sorts of scientific questions.... [T]he early developmental stages of most sciences have been characterized by continual competition between a number of distinct views of nature, each partially derived from, and all roughly compatible with, the dictates of scientific observation and method. 2. Indispensability of auxiliary elements: The auxiliary elements that go into determining a unique view of the world are indispensable to the success of science: they ground and guide progress. (N.B. Importance of consensus.)

12 Three phases of science 1. Immature science. No, or very little, agreement over fundamentals; a plurality of different standards and worldviews. 2. Normal science. [R]esearch firmly based upon one or more past scientific achievements [ paradigms ], achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice. 3. Revolutionary science. A wholesale shift in: which problems are available to scientific scrutiny (what is worth doing); standards for legitimate solutions; the world in which scientific work is done (i.e. the dominant worldview); the impression of previous theories (e.g. the reason for their success). For 2 vs. 3, think: Le Verrier and Neptune vs. Mercury and relativity.

13 Theories as structures

14 A picture of scientific progress Pre-paradigm ( immature ) science Normal science: puzzle solving in a paradigm Crisis: the build up of anomalies Revolution: a paradigm change Normal science (again) Crisis (again) Revolution (again)...

15 E.g. Optics Pre-paradigm ( immature ) optics Newtonian optics: light as corpuscles Crisis: e.g. the Arago/Poisson/Fresnel spot, double-slit experiment Wave optics (e.g. Young, Fresnel): light as waves Crisis: e.g. double-slit experiment (again!), photoelectric effect Quantum optics (e.g. Planck, Einstein, Pauli): light as photons...

16 E.g. Dynamics Pre-paradigm ( immature ) dynamics Aristotelian dynamics: natural motion Crisis: e.g. Galileo s ship, leaning tower of pisa experiment Newtonian dynamics: force and inertia Crisis: e.g. Eddington s expedition, ether wind experiments Einsteinian dynamics: spacetime, gravity as inertia...

17 Paradigms Normal science is characterized by research done in a paradigm, or collection of paradigms. Paradigm means an example, or template; e.g. grammatical paradigms. For Kuhn it means: a scientific achievement that serves to shape future theoretical development. A better example may be case law, as opposed to statutory law. Normal science consists in the actualization of [the] promise [of early achievements], an actualization achieved by extending the knowledge of these facts that the paradigm displays as particularly revealing, by increasing the extent of the match between those facts and the paradigm s predictions, and by further articulation of the paradigm itself. (p. 24)

18 Paradigms No natural history can be interpreted in the absence of at least some implicit body of intertwined theoretical and methodological belief that permits selection, evaluation, and criticism. If that body of beliefs is not already implicit in the collection of facts in which case more that mere facts are at hand it must be externally supplied, perhaps by a current metaphysic, by another science, or by personal and historical accident.... What is surprising, and perhaps unique in its degree to the fields we call science, is that such initial divergences should ever largely disappear. (p. 17) Normal science is characterized by wide consensus, which is not challenged. (Contrast with falsificationism.) Paradigms structure evidence: which facts are particularly revealing, how the facts are to be interpreted (signal vs. noise).

19 Flat vs. round earth

20 The advantage of paradigms Paradigms permit specialization. By focusing attention upon a small range of relatively esoteric problems, the paradigm forces scientists to investigate some part of nature in a detail and depth that would otherwise be unimaginable. (p. 25) New paradigms are associated with the formation of new specialized journals and societies even (sometimes) with a new name (e.g. bioinformatics, nanoscience, quantum information theory ). Examples: Aristotle s theory of motion; Ptolemy s computations of planetary orbits; Lavoisier s application of the balance; Maxwell s mathematization of the electromagentic field.

21 Experimental work during normal science Work during normal science is both experimental and theoretical. Normal foci for experimental investigation: Collection of facts that are (according to the paradigm) particularly revealing of the nature of things. E.g. Astronomy: stellar positions & magnitudes; orbits,... Physics: specific gravities; compressibilities; conductivities,... Chemistry: combustion & combining weights; boiling & melting points; structural formulae,... Collection of facts that are easy to compare with predictions. Further articulation of the paradigm. (Paradigms help here in narrowing down what there is to look for.) Resolving ambiguities; measuring physical constants; formulation of mini-laws (e.g. Boyle s Law, Coulomb s Law)

22 Theoretical work during normal science Normal foci for theoretical investigation: Generating predictions of factual information of intrinsic value (e.g. mass of Earth; moment of inertia of a cube). Generating predictions for experimental testing. Perhaps a new application of the paradigm; or an increase in precision of previous applications. Designing experiments (guided by the paradigm); extracting observable predictions (harder than it sounds!) Further articulation of the paradigm. E.g. increased rigor of mathematical framework (e.g. rigorization of the differential calculus, Hamilton-Jacobi theory); subsumption of new systems under the paradigm (e.g. Newtonian point masses continuous fluids).

23 Normal science as puzzle-solving Kuhn describes work in a paradigm as puzzle-solving, due to the following analogous features: Puzzles have an assured solution ( unlike cancer or world peace ) other problems are deemed metaphysical or insoluble. Puzzles are associated with a limited collection of rules, standards and acceptable steps in seeking and appraising a solution. Puzzles are small enough to give individuals a sense of achievement in their careers. A paradigm can, for that matter, even insulate the community from those socially important problems that are not reducible to the puzzle form, because they cannot be stated in terms of the conceptual and instrumental tools the paradigm supplies. (p. 37)

24 The priority of paradigms Lack of a standard interpretation or of an agreed reduction to rules will not prevent a paradigm from guiding research. Normal science can be determined in part by the direct inspection of paradigms, a process that is often aided by but does not depend upon the formulation of rules and assumptions. Indeed, the existence of a paradigm does not even imply that any full set of rules exists. (p. 44)

25 Wittgensteinian family resemblance

26 Paradigms, not rules Wittgenstein on game : it is foolish to demand necessary and sufficient conditions in any account of competent linguistic practice. Explicit rules tend to be demanded only in cases of strife or disagreement (i.e. just before or during revolutionary science). Why paradigms and not rules? 1. Rules are hard to discover. 2. Humans (including scientists!) learn by doing, not by internalizing explicit rules. 3. Rules are unnecessary (and even limiting) in times of consensus. 4. Consensus over rules is hard to achieve: paradigms permit textured variation within the scientific community.