Transcript THE NATURE OF SCIENCE - Johns Hopkins University

THE NATURE OF
SCIENCE
Understanding and Teaching Biological
Sciences
Summer 2009
What is Science?

“A field of study based on memorization of
boring facts that have little relevance to my
life. People who are almost always right,
never unsure of them, relatively
emotionless, and often arrogant, practice
it. They are not at all like me.” (A student,
NABT Conference, 2009)
Science as a way of knowing!

Research suggests that most students do not
adequately understand the nature of science
(McComas, 1996; Moore, 1993; Horner &
Rubba, 1979).

Understanding “what science is and what its
limits are” must be a key component of science
teaching and learning (Moore, 2009).
NATURE OF SCIENCE

How is science different from other ways
of knowing?

Why is important to know and understand
the epistemology of science?
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How is knowledge constructed in science?
The Portrait of Science
The scientific Worldview
 The natural world works in “consistent patterns”
 Events, and phenomena are interconnected
 The universe is a “vast single system”; knowledge
gained from studying one part of it can often be
applied to other parts
 Scientific ideas are constantly tested against
nature
 Scientific theories are tentative and subject to
change or modification through new observations,
data, and evidence (AAAS, 2004)
Scientific Knowledge: Continuity, Stability,
and Evolution
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Scientists are able to make accurate predictions about
the natural world by building scientific models and
theories to explain natural phenomena
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Scientists rely on physical cause and effect only Scientific models are approximations of nature
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The role of physical evidence in science

Scientists often disagree over evidence interpretations of
data, and inferences
Nature of Science
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Scientific theories are debated, contested, revised, and
sometimes replaced in the light of new evidence/data

The role of new inventions, tools, and technology in
advancing scientific knowledge
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Theories are judged by their results
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How is scientific knowledge communicated?
Conferences, Journals (AAAS, 2004)
Can science explain spiritual and religious
questions/ideas?
Normal science vs. Scientific revolutions
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Normal science is a puzzle solving activity where scientists
solve “empirical puzzles” within the framework of an overarching paradigm

Problem-solving an attempt to reduce the gap between
observation and theory
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Normal science research is “cumulative”

Those problems are usually selected which can be solved
using the “existing paradigm, technique,” and technology
(Kuhn, 1992)
Crisis in science
“Crises are a necessary precondition for the emergence of
novel theories” (Kuhn, 1992)

Nature vs. conceptual paradigms; discrepancies between
observation and predictions

Anomalies, conflicts, contradictions, and “counter instances”
emerge

Further “articulations” and “ad hoc modifications” of the existing
theory
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Anomalies persist and also resistant to be incorporated into
existing paradigms; result a crisis
(Kuhn, 1992)
Early Chemistry
Earth
 Air
 Fire and
 Water
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Role of anomalies in generating a crisis
(1) Early chemical theory of fire
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All combustible substances composed of a substance
called phlogiston (from Greek, meaning "burned").
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The phlogiston theory explained numerous physical and
chemical phenomena
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Explained why metals had common properties


phlogiston produced common properties
Explained why substances burned
- Burning was caused by the liberation of phlogiston
from the substance
- Ash or residue was “dephlogisticated.”
New theories

Lavoisier (1780) refuted the phlogiston
theory. His experiments (1780) led to the
view that matter is not a “structure less
continuum.”
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Transformations of matter could be
investigated quantitatively by measuring the
masses of substances consumed and
produced in reactions; total mass same; law
of fixed proportions, conservation of mass.
Reconceptualizing Chemistry
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Dalton (1803) finally developed the atomic theory;
explained physical and chemical changes

Chemical reactions involved combination and
separation of atoms, in simple whole number ratios.
“Scientists stopped writing that the oxides of carbon
(CO and CO2) contained 56% and 72% of oxygen by
weight” (Kuhn, 1992)
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A completely new way of conceptualizing and
practicing chemistry
Scientific revolution
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A valid paradigm is renounced only when an “alternate
candidate” is available to take its place
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New theory should make different predictions
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After the revolution, scientists’ need to be “re-educated”
to understand the world through the new paradigm
E.g. Copernican heliocentric paradigm changed
the meaning of the term planet; celestial bodies
including the sun, stars, and planets were seen very
differently
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New technology also opens up avenues for new
observations and testing
Falsificationism
“The criterion of scientific status of a theory is its
falsifiability, refutability, or testability” (Karl
Popper, 1963)
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“Easy to obtain confirmations, or verifications, for nearly every
theory - if we look for confirmations” only

“Confirmations should count only if they are the result of risky
predictions”;
E.g., Einstein’s gravitational theory & Eddington’s
expedition measuring predicted deflected light
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A theory is “non-scientific” if it is not refutable”
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Irrefutability not a “virtue, but a vice.”
(Popper, 1963)
Progressive vs. Degenerative Theories
Theories are not always refuted, but replaced by better theories
Scientists are engaged in rival research programs
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Hard Core (“Unchangeable and unchallengeable ideas”)
–Central Idea
–Difficult to test directly
–Protected from refutation by ‘protective belt’ of auxiliary
hypotheses
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Auxiliary Hypotheses:
–‘Protective Belt’ of research program
–Which problems to pursue - sets of puzzles to solve
(Lakatos, 1978)
Progressive vs. Degenerative research
Programs
•Progressive
–New Theory consistent with all of known facts
–New Theory predicts new facts
–Empirical support of new predictions
•Degenerative
–New theory only generated after some novel
observation
–Lack of empirical support for new predictions
Discussion Points

What features of scientific inquiry would
you like to highlight in your own classes or
in other biology/science classes at your
school?