Scientific Realism: Appearance and Reality

1
Scientific RealismAppearance and Reality

• Reality what a concept
• Ian Hacking

2
Scientific realism

• Metaphysical questions Appearance and reality
• Key terms
• Metaphysical realism
• Direct realism
• Ideaism
• Causal realism

3
Why metaphysical questions?

• Science appears to tell us the fundamental
  structures of the world in which we live the
  composition of matter and the physical laws which
  they obey
• Regardless of the nature of scientific method and
  how we justify knowledge claims in science, there
  are questions about whether we ought to believe
  what scientific theories tell us about reality
  beyond the appearance of things.

4
Appearance and reality The two tables

• The ordinary table It has been familiar to
  me from earliest years. It is a commonplace
  object of that environment which I call the
  world. How shall I describe it? It has extension,
  it is comparatively permanent it has colour
  above all it is substantial. It is a thing
  Arthur Eddington, The Nature of the Physical
  World, cited on p. 131

5
Appearance and Reality

• Contrast the scientific table It does not
  belong to the world previously mentionedthat
  world which spontaneously appears around me when
  I open my eyes. It is part of a world which in
  more devious ways has forced itself on my
  attention. My scientific table is mostly
  emptiness. Sparsely scattered in that emptiness
  are numerous electric charges rushing about with
  great speed but their combined bulk amounts to
  less than a billionth of the bulk of the table
  itself Eddington, p. 131

6
Common sense vs. scientific world

• Do boththe commonsense (appearance) scientific
  (reality)tables exist? What is the relation
  between the two worlds?
• This question of appearance and reality
  gained prominence during the scientific
  revolution in the 17th Century. However, the
  question of appearance and reality dates back
  to the beginning of Western philosophy
• E.g. the early Atomists solution

7
Historical roots scientific revolution

• The key analogy used in the scientific revolution
  the is to compare Nature to a giant clockwork
  mechanism Inner mechanisms produce outward
  appearance
• Science aims at understanding the inner
  mechanisms responsible for our observations
• So we perceive with our senses may not be
  properties that things have in reality

8
Scientific revolution

• Philosophers who supported the scientific
  revolution held that objects were made up of
  corpuscles (recall the atomists solution).
• Lockes example gold
• How does gold appear to us? How do we know that
  those features that appear to us are golds
  essential properties?

9
Primary vs. Secondary properties

• What is responsible for golds appearance?
• Locke used the terms real essences for primary
  properties, and nominal essences for secondary
  properties.

10
Primary vs. Secondary properties

• Descartes wax example It has been quite
  freshly from the hive, and it has not yet lost
  the sweetness of the honey which it contains
  its colour, its figure, its size are apparent it
  is hard, cold, easily handled But notice while I
  speak and approach the fire what remained of the
  taste is exhaled, the smell evaporates, the color
  alters, the figure is destroyed, the size
  increases, it becomes liquid Descartes,
  Meditations of First Philosophy

11
Primary vs. Secondary properties

• Primary properties those properties that things
  not only appear to have, but which they also have
  in reality (Ladyman 134)
• Secondary properties those properties which
  things appear to have but which they dont
  possess in themselves, only in the mind of the
  observer (ibid.)
• Here think about color, odor. Are they properties
  that an object have in reality, i.e. independent
  of us, or do they depend on the observer?

12
Primary vs. Secondary properties

• Primary properties are those that exist in an
  object whether we perceive them or not Secondary
  properties do no exist unperceived
• Primary properties have the disposition, or
  power, to produce a particular kind of sensation
  (say the color yellow) in us, but there is
  nothing resembling our experience of color in the
  primary properties themselves

13
Primary vs. Secondary Properties

• What are examples of primary properties?
• Extensionproperties that are quantifiable (137)
• Eddingtons scientific table is made up of
  primary properties described by todays science
  his everyday table bears the secondary properties
  of everyday experience
• What is the relation between our experience of
  things and their primary properties? How can know
  about the primary properties of things since they
  are not observable (inner mechanism)?

14
Metaphysical issues variety of realisms

• Metaphysical Realism our ordinary language
  refers to, and sometimes say true things about, a
  mind independent world (138).
• What does mind-independence mean?
• The issue for philosophy of science is not
  whether the objects described by science exist
  but how we can know that they exist and what
  their natures are (ibid)

15
Direct Realism

• One solution to the question of how we can know
  that they exist and what their natures are is
  direct realism
• Direct realism there are external objects that
  exist independently of our minds and which we
  directly perceive with our senses (139).

16
Direct realism

• Arguments against direct realism
• Illusions
• How sense perception really workscontribution by
  our brains

17
Ideaism

• Perhaps what we perceive in our minds are
  ideas, or representations
• The view that the immediate objects of
  perception is ideas in the mind, rather than
  objects in the external world is call Ideaism
  (140)
• First distinguish between ideas and
  impressions
• Impression is what is forced on the mind by the
  senses Idea is the image of that impression
  that one can bring before our mind at will (141)

18
Ideaism

• Ideaism is a theory about perception
• Ideaism contradicts direct realism it does not,
  however, say that there are no external objects
• Objects in the world cause the impressions we
  have of them
• Causal realism there are external objects that
  exist independently of our minds and which cause
  our indirect perception of them via the senses
  (141).

19
Consequences of causal realism

• Once we adopt causal (representative, or
  indirect) realism, we have a gap between the
  world as we perceive it and the world as it is.
• The gap gives rise to skepticism, that we may be
  massively mistaken about the external world
• Next time, well discuss solutions to the
  epistemic gap introduced by representative
  realism