Transcript PPTX file - UCL Department of Geography

Graham Bradley
Lecture 2
Is science rational and progressive?
 Realism and instrumentalism
 Inference to the best explanation
 Criteria for theory choice
 Logical positivists
 Thomas Kuhn and
revolutions in science
 Constructivism
 Examples: plate tectonics and geomorphology
A scientific realist says...
“A 1950s education in Freud, Marx, and
modernism is not a sufficient qualification
for a thinking person. Indeed, the traditional intellectuals
are, in a sense, increasingly reactionary, and quite often
proudly (and perversely) ignorant of many of the truly
significant intellectual accomplishments of our time.
Their culture, which dismisses science, is often nonempirical. It uses its own jargon and washes its own
laundry. It is chiefly characterized by comment on
comments, the swelling spiral of commentary eventually
reaching the point where the real world gets lost.”
John Brockman (science publisher – www.edge.org)
Scientific Realism
versus
Instrumentalism
 Scientific realism – the aim of science is to provide true
theories of the world
 All theories are attempted descriptions of reality
 Instrumentalism (anti-realism) – the aim of science is
to provide predictive theories only
 Not ‘global anti-realism’ i.e. poststructuralism (language trap)
 Science provides true descriptions of the observable universe
but has no knowledge of unobservable universe
 Scientific theories are instruments to predict observations
Do scientific theories represent reality?
1. How do we know current theories are true if
past theories were found to be false?
 Quantity and quality of observational evidence
2. How do we know which theories are true if
multiple theories are consistent withdata?
 Science requires additional criteria to make an
‘inference to the best explanation’
Inference to the Best
Explanation
 A type of non-deductive inference
 On Christmas morning presents had been left by the tree and
the mince pies and sherry were gone!
 Late on Christmas Eve footsteps were heard on the staircase
 Who delivered the presents and ate the goodies?
 We learn to infer the ‘best explanation’ based on
personal criteria and experience
natural
selection
intelligent
design
What are the criteria for
choosing explanations?
 Accuracy, scope, consistency, fruitfulness, simplicity etc.
 E.g. Evolution by natural selection
 explains similarities by descent from a common ancestor
 replication & mutation & competition → adaptation
 Simplicity (parsimony) and explanatory power are evidence of its
truth
 How do you know that reality is simple and not complex?
The Logical Positivists
(1920s to 1960s)
 Impressed by objectivity of science and verification
 ‘Context of discovery’ – historical, emotional, subjective
 ‘Context of justification’ – testing, evidence, objective
e.g. Kekule and the structure of benzene
 They thought philosophy of science
should address justification of theory
 They were not interested in history
Thomas Kuhn (1922 - 1996)
Is sociology of science important?
 An historian of science who
thought that ignoring history
gives a naïve picture of the scientific enterprise
 Interested in ‘scientific revolutions’ – when
scientific ideas are replaced by radically new ones
 e.g. Einsteinian revolution in physics, Darwinism
in biology, plate tectonics in geology
Reference: Kuhn, T. S., 1962. “The Structure of Scientific Revolutions”
Paradigms
 Shared assumptions, beliefs and values that
unite the community and allow ‘normal science’
to take place
 Two components:
 A set of fundamental theoretical
assumptions accepted by the scientific
community
 A set of ‘exemplars’ – classic problems
solved by these theoretical assumptions
‘Normal’ Science
 A paradigm defines ‘normal science’ for a period
 sets the standards and specifies objectives for
relevant research
 coordinates research and initiates students into the
tradition
 Scientists work within a paradigm
to solve minor puzzles
 When anomalies are few they
are ignored
Revolutionary Science
 As anomalies accumulate a crisis develops
 Confidence in the old paradigm breaks down
 Fundamental scientific ideas are up for grabs
 Paradigm shift – a new paradigm is established
Example 1: Tectonic shifts in paradigm?
19th century: Static Continents
 Observations: uplifted strata, geological folds
and faults
 E.g. James Dana – Manual of Geology (1863)
 Explanations (no unifying theory):
 undermining due to volcanic eruptions
 sudden formation of volcanic vapours
 weight of accumulated formations
 movement of the globes interior fluids
 temperature related expansion
and contraction
Earlier 20th century growing unease
 Observations:
 matching coastlines
 continuity of Permo-
Carboniferous glacial sediments
 similar fossils records
 Explanation: continental drift
(Alfred Wegener, 1912)
 Not generally supported due
to lack of evidence for a suitable
mechanism
Later 20th century:
Plate Tectonics…a paradigm shift?
 Observations:
 earthquake zones & deep earthquakes beneath ocean trenches
 variable magnetic field direction in rocks of different ages (1956)
 magnetic striping at ocean ridges suggests seafloor spreading
(1961)
 Explanations: constructive margins, subduction zones etc
 Unifying theory for geology & geomorphology of the Earth
Can paradigms be compared?
 Kuhn - alternative paradigms so different they cannot
be compared - no common language for translation
 e.g. Newtonian and Einsteinian physicists (supposedly) have
a different concept of mass and in discussion they talk past
each other
 Criticism of ‘incommensurability’:
 If it is agreed that theories are incompatible then they must
be comparable and cannot be incommensurable
 Kuhn: Newton’s and Einstein’s theories are incompatible
Are data independent and objective?
 Cannot isolate theory-neutral data because:
 Perception is conditioned by background beliefs
 Reporting of data is couched in theoretical language
 Criticisms of ‘theory-ladenness of data’:
 Data may be adequately free of theoretical
contamination to be acceptable to proponents of
alternative paradigms
 e.g. Believers in geocentric and heliocentric paradigms
could still agree on statements like ‘on 14th May the
Sun rose at 5:30 am’
Some criticisms of Kuhn’s ideas...
 ‘Between Kuhn’s “normal science” and
“extraordinary science” there are many gradations’
(Popper, 1970)
 ‘If an experiment does not hold out the possibility
of causing one to revise one’s views, it is hard to
see why it should be done at all’ (Medawar, 1979)
Example 2: Changing paradigms in geomorphology?
Catastrophism uniformitarianism
Shift
(Orme, 2002 – Geomorphology 47)
landscape cycles quantitative methods
Shift
(Orme, 2002 – Geomorphology 47)
Kuhn’s controversies:
 Is science rational?
 Adopting a new paradigm involves a degree of faith and
is not purely based on objective evidence
 The transfer of allegiance from one paradigm to another
is a ‘conversion experience’
 Peer pressure plays a large role in paradigm acceptance
 Is science progressive?
 ‘Facts’ about the world are paradigm-relative
 Scientific knowledge is not necessarily cumulative
 Does the concept of objective truth even make sense?
Kuhn’s clarifications…
 Science may be viewed as rational
 Incommensurabilty between paradigms is partial
 Paradigm choice is made by reasonable shared criteria:
accuracy, scope, consistency, simplicity, fruitfulness etc.
 Paradigm choice based on reasonable shared criteria is
rational
 Science may be viewed as progressive
 ‘Conceived as a set of instruments for solving technical
puzzles in selected areas, science clearly gains in
precision and scope with the passage of time. As an
instrument, science undoubtedly progresses’
So...can the scientific method be
rigorously defined?
 Many have attempted to define the criteria for a good
theory
 Simplicity (parsimony), breadth, goodness of fit etc.
 No rigorous algorithm (sequence of instructions)
 Kuhn claimed there is no algorithm for theory choice
 Science appears to conform to a looser definition and
more relaxed concept of rationality than often
assumed
Summary
 Realism and instrumentalism
 Inference to the best explanation
 Logical positivists emphasis on theory
 Thomas Kuhn’s emphasis on history
 Paradigms, normal and revolutionary science
 Science is more loosely defined than often assumed
 Science is rational when viewed against shared criteria
 As an instrument, it progressively solves empirical
questions
Final thought: What are appropriate and
inappropriate applications of science in geography?