From Logical Positivism to Scientific Realism

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From Logical Positivismto Scientific Realism

• Theories dont have to be true to describe what
  we observe correctly. As far as science is
  concerned, all that matters when it comes down to
  it is getting the predictions right for what we
  observe. Lots of different theories that disagree
  about what the unobservable world is like could
  still agree in what they predict about the
  results of experiments
• Ladyman (123, 160)

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Announcement
The final exam is scheduled for 630 pm Thursday
April 19 in SBE 1220
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Positivist epistemology

• Positivists hold that our knowledge is built up
  from basic beliefs which are self-evidently true
  (i.e. immune from doubt)
• All other beliefs are justified either
  deductively or inductively from basic beliefs
• Basic beliefs are called protocol statements
  first person, singular, present tense,
  introspective reports (152).

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Dilemma for Logical positivism

• We (claim to) know lots about the world
• We only know protocol statements and analytic
  truths
• How to move from private sense-data to public
  objects?
• Solution Proposition asserting the existence of
  physical objects are equivalent to ones asserting
  that the observer will have certain sequence of
  sensations in certain circumstances (153).

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Logical positivism phenomenalism

• Physical objects are permanent possibility of
  sensation they are logical constructions out
  of actual and possible sense experience (ibid).
• What about theoretical terms, terms such as
  positron that refer to unobservable entities?

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Logical positivism theoretical terms

• Given their commitment to empiricism, logical
  positivists face a difficulty with theoretical
  terms, namely how can they be meaningful?
• How do terms get meaning for concept empiricism?
• Built up from simple ideas.
• What about charm?

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Theoretical terms

• One way to address the problem of theoretical
  terms is to think in terms of kinds of statements
  
• Assertoric statements are those can be true or
  false they assert something about the world
• Consider Wong is 2m tall and Damn it!
• Two options
• Statements using theoretical terms are not
  assertoric
• Statements using theoretical terms are assertoric

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First option semantic instrumentalism

• Statements using theoretical terms are not
  assertoric
• Some concepts are useful fictionse.g. the
  average male professor at Wilfrid Laurier
• This position is semantic instrumentalism (155)
• Statements involving them are not assertoric but
  they are useful.
• On this view, theoretical terms do not literally
  refer to entities they are useful tools to
  systematize relations between phenomena

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Second option Reductive empiricism

• If you hold that statements using theoretical
  terms are assertoric, then you can define, or
  reduce, theoretical terms in terms of words that
  refer to everyday sensory experience
• Reductive empiricism theoretical terms can be
  defined in terms of observational concepts, hence
  statements involving them can be assertoric
  (155)
• Since theoretical terms are given operational
  definitions, they do not refer to unobservable
  entities.

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Problems for Reductive Empiricism

• First problem Operational definitions introduce
  too many properties
• E.g. 100 degrees Celsius
• How to systematize the properties?

• Second problem How is certain knowledge
  possible?
• Use of public language suggests that observation
  reports are fallible

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Reductive empiricism to scientific realism

• However, you can maintain that theoretical terms
  do refer to unobservable entities, that is, what
  science tells us is literally true
• It is the mind-independent world that makes our
  assertoric statements true or false. This view is
  related to the correspondence theory of truth
  (157)

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Three requirements of scientific realism (158)

• Metaphysical requirement
• Entities or kinds of entities talked about S
  exist
• Existence of entities is independent of our
  knowledge and minds
• Semantic requirement
• Statements about S are irreducible and are
  genuinely assertoric
• Truth conditions for statements of S are
  objective and determine the truth or falsity of
  those statements depending on how things are in
  the world..

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Requirements of scientific realism

• Epistemic requirement
• Truths about S are knowable and we do in fact
  know some of them, hence the terms of S
  successfully refer to things in the world
• If you were a scientific realist about sub-atomic
  particles, then you are committed to the
  following
• Positrons exist mind-independently
• Statements about positrons are about subatomic
  particles
• These statements are true/false depending on how
  the world is
• Truths about positrons are knowable, and we do
  have some

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Anti-realism

• Anti-realism is the position that rejects any
  one of the three requirements of scientific
  realism, or a combination of them
• You can deny the requirement that the truth
  conditions are determined by how things are in
  the world by challenging the correspondence
  theory of truth
• How would you cash out the relation of
  correspondence in the correspondence theory if
  you were an empiricist?
• Or, if you were a social constructivist, you
  would hold that truth is by convention

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Anti-realism

• Alternatively, you can challenge the claim that
  we should take what scientific theories tell us
  literally
• Here think about the following observation about
  data and theory Data are typically compatible
  with more than one theory. Some of these theories
  are incompatible with one another.
• Which theory should we take to be literally true?
• This is the problem of Underdetermination theory
  is underdetermined by data.
• We will examine the argument from
  underdetermination next week