Transcript Chapter 22: Advanced Querying and Information Retrieval

What is this thing called
Science ?
A.F. Chalmers
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Induction
• Start with the data – then get the theory
– “Science is based on what we can see and hear
and touch, etc. Personal opinion or preferences
and speculative imaginings have no place in
science” p2
– “If a large number of As have been observed
under a wide variety of conditions, and if all
those observed As without exception possessed
the property B, then all As have the property B”
p5
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Deduction
• Start with a theory – then get the data
– All men are mortal
– Fred is a man
– Therefore Fred is mortal
• Benefits
– Can make predictions
– Can explain data
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Discussion Points
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Errors in measurements
Missing information
Measuring the wrong thing
Multiple theories for the same data
Everything is everything
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Falsification
• Popper’s reaction to Induction
• Key Premise
– We can’t prove that a theory is true, but we can
prove that it is inconsistent with data
• Implications
– The theory has to be testable
– The theory makes definite claims
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Issues with Falsification
• “The more a theory claims, the more
potential opportunities there will be for
showing that the world does not in fact
behave in the way laid down by the
theory” p 42
• How do you get decide what data to get
?
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The Structure of Scientific
Revolutions
Thomas S. Kuhn
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Phases in Science
• Pre-scientific
– Incompatible / incomplete theories
• Normal science
– One accepted theory
– Expand scope of theory / explain disagreements
• Revolutionary Science
– New theory (Paradigm shift)
– Explains all data from previous theory +
disagreements
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What evidence would support
Kuhn’s theory ?
“… if I am right that each scientific revolution alters
the historical perspective of the community that
experiences it, then that change of perspective
should affect the structure of postrevolutionary
textbooks and research publications. One such
effect – a shift in the distribution of technical
literature cited in the footnotes to research reports
– ought to be studied as a possible index to the
occurrence of revolutions” p xi
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A Role for History
“display the historical integrity of that
science in its own time”. They ask for
example, not about the relation of
Galileo’s views to those of modern
science, but rather about the relationship
between his views and those of his
group, i.e.. His teachers, contemporaries
and immediate successors in the
science” p 3
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Science as a Complex System
Mind
Science
Society
Nature
Thagard (1999) How Scientists Explain Disease
p220
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The Route to Normal Science
“No period between remote antiquity and the
end of the seventeenth century exhibited a
single generally accepted view about the
nature of light. Instead there were a number
of competing schools and subschools, most of
them espousing one variant or another of
Epicurean, Aristoliean or Platonic theory” p
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“… no standard set of methods …” p 13
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The Route to Normal Science
• Darwinian
– “ Those unwilling or unable to attach
themselves to some group must proceed in
isolation or attach themselves to some
other group” p 19
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What evidence would be
required ?
• “In the sciences … the formation of
specialized journals, the foundation of
specialists’ societies and the claim for a
special place in the curriculum have
usually been associated with a group’s
first reception of a single paradigm” p
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The Nature of Normal Science
• “Paradigms gain their status because
they are more successful than their
competitors in solving a few problems
that the group of practitioners has come
to recognize as acute” p 23
• How does this fit with Reed’s statement that
scientists of the future will be judged on the
quality of their questions ?
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Normal Science
• Key Qualities
– Explanatory power
– Predictive power
– Data collection to verify the theory
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Anomaly
• discovery is not akin to our concept of
seeing
• “.. Any attempt to date the discovery
must inevitably be arbitrary because
discovering a new sort of phenomenon
is necessarily a complex event, one
which involves recognizing both that
something is and what it is” p 55
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Response to Crisis
• “The scientists who pauses to examine
every anomaly he notes will seldom get
significant work done. We therefore
have to ask what it is that makes an
anomaly seam worth concerted
scrutiny” p 82
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Crisis and Emergence of
Scientific Theories
• “in the sciences fact and theory,
discovery and invention, are not
categorically and permanently distinct”
p66
• Forest through the trees?
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Fitting data to theories
• “Philosophers of science have repeatedly
demonstrated that more than one theoretical
construction can always be placed upon a
given collection of data.” p 76
• “Lack of a standard interpretation or of an
agreed reduction to rules will not prevent a
paradigm from guiding research” p 44
• What are the implications re Science 2020 ?
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Response to Crisis
• “.. The act of judgment that leads scientists to
reject a previously accepted theory is always
based upon more than a comparison of that
theory with the world. The decision to reject
one paradigm is always simultaneously the
decision to accept another, and the judgment
leading to that decision involves the
comparison of both paradigms with nature
and with each other”, p77
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Scientific Revolution
• “those non-cumulative development
episodes in which an older paradigm is
replaced in whole or in part by an
incompatible new one.” p 92
• “To outsiders they may, like the Balkan
revolutions of the early twentieth
century, seem normal parts of the
development process” p 93
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Paradigm Shifts
• “At that point the society is divided into
competing camps or parties, one
seeking to defend the old institutional
constellation, the others seeking to
institute some new ones” p 93
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Paradigm Shift
• Paradigms … are the source of the
methods, problem-field, standards of
solution accepted by any mature
scientific community at any given time”
p 103
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Revolutions as changes in
world view
• “during revolutions scientists see new
and different things when looking with
familiar instruments in places they have
looked before” p 111
• What if all the data from earlier
experiments was available and you
could effortlessly test your new theory
against the existing data.
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