Realism vs Anti-realism

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RealismvsAnti-realism
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Topics

• The Problem of Unobservability
• The No Miracles Argument
• The Observable / Unobservable Distinction
• The Underdetermination Argument for Antirealism

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The Problem of Unobservability

• Observable ordinary objects
• Unobservable theoretical objects
• Note theoretical ? unobservable, e.g. mass,
  element.

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• Questions
• Do unobservable theoretical entities really exist
  and are their descriptions true?
• Is theoretical knowledge about unobservables
  possible? (Cf. also the Problem of Induction)
• Are unobservable theoretical constructs merely
  instruments for making observable predictions
  without ontological import?
• E.g. center of mass does not refer to any
  physical objects, but a spatial point only.

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• Realist anti-realist interpretations of the
  kinetic theory of gases
• It can correctly predict various observable
  behaviour of gases, e.g. Boyles Law.

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• Realism
• The aim of science is to provide a true
  description of both the observable and
  unobservable part of reality
• This aim is attainable.

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• Antirealism (or Instrumentalism)
• The aim of science is to provide a true
  description of the observable part of the world
  only.
• For the unobservable part, only agnosticism is
  possible.
• Unobservable theoretical constructs are for us
  merely instruments for making observable
  predictions.

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• Copernicuss theory was originally interpreted
  antirealistically by Osiander who wrote the
  Preface for Copernicuss main work, On the
  Revolutions of the Heavenly Bodies
• . . . it is the duty of an astronomer to compose
  the history of the celestial motions through
  careful and skillful observation. Then turning to
  the causes of these motions or hypotheses about
  them, he must conceive and devise, since he
  cannot in any way

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• attain to the true causes, such hypotheses as,
  being assumed, enable the motions to be
  calculated correctly from the principles of
  geometry, for the future as well as the past. The
  present author Copernicus has performed both
  these duties excellently. For the hypotheses need
  not be true nor even probable if they provide a
  calculus consistent with observation that alone
  is sufficient.

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The No Miracles Argument

• The positive argument for realism is that it is
  the only philosophy that doesnt make the success
  of science a miracle H. Putnam

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• Main points of the argument
• What explains the theorys close fit with the
  observational data?
• Being an antirealist is akin to believing in
  miracles.
• So, realism is more plausible.

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• One historical reason for accepting the atomic
  thesis in the early 20th century
• Convergence on Avogadro's number under
  measurements in such diverse phenomena as
• Brownian motion,
• alpha decay,
• x-ray diffraction,
• electrolysis,
• blackbody radiation, and so on.
• What is the best explanation?

Ref. http//www.soc.iastate.edu/sapp/phil_sci_lec
ture18.html
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• It is an inference to the best explanation (IBE)
• X Convergence on Avogadro's number
• A The atomic thesis
• P1 A explains X better than its rivals, B, C,
  and so on.
• P2 The ability of a hypothesis to explain
  something better than all its rivals is a mark of
  its truth.
• C Hence, A is true.
• A sort of reasoning commonly used in daily life,
  e.g. Sherlock Holmes
• http//www.bakerstreet221b.de/canon/sign-01.htm
• The Science of Deduction

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• One anti-realist response
• Counterexamples from the history of science
• E.g. the phlogiston theory of combustion
• Widely accepted until the end of the 18th century

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• Realist refined argument
• By appealing to approximate truth rather than
  exact truth.
• Must empirical success lead to approximate truth?

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• Counterexample from the history of optics
  drastic changes of the conception of light
• Newtons (1642-1727) theory
• Light as beams of material corpuscles
• Fresnels (1788-1827) theory
• Light as transverse wave in an all-pervasive
  elastic medium - ether

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• (Modified) Maxwells (1831-1879) theory
• Light as fluctuating electric and magnetic
  fields-in-themselves without medium
• Einsteins (1879-1955) theory
• Light as quanta, the photons

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• These theories were empirically successful and
  had made progress, but did they move closer and
  closer to the truth?
• What is light?
• Material particles
• Waves in an elastic medium, ether
• Fluctuating fields-in-themselves
• Photons
• Next ???

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• Also, it seems difficult to regard, say,
  Fresnel's theory as approximately true, since
  ether - a basic entity in the theory - is now
  believed not to exist.

Would you think that this picture gives you an
approximately true depiction of the environment
if in fact there was no fog there?
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• Paper topics?
• What is approximate truth?
• What notion(s) of approximate truth is(are)
  relevant to this dispute? How?

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• The moral drawn by the antirealist
• Modern scientific theories should not be taken as
  even approximately true, just because they are so
  empirically successful.
• But one may suggest
• An empirically successful theory is probably on
  the right line.
• Which interpretation of probability is involved?
• Frequency, subjective, logical, and so on.
• Would this sense of probability help solve the
  problem?

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Some Positions in the Debate

• An influential form of antirealism
• Van Fraassens constructive empiricism
• Weaker forms of realism
• Convergent realism
• Karl Poppers conjectural realism
• Ian Hackings Nancy Cartwrights Entity Realism
  
• Attempts to capture the best of both worlds
• A. F. Chalmerss unrepresentative realism
• John Worralls structural realism

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An Analogy to Positions in Theology
claims about unobservables are true false cant tell
interpreted literally realism fundamentalism fictionalism atheism constructive empiricism agnosticism
interpreted nonliterally positivism liberal theology