Transcript Science and the Ways of Knowing - TOK-eisj

Science and
the Ways of Knowing
What is Science?
Equipped with his five senses, man explores
the universe around him and calls the
adventure Science.
Edwin Hubble
Science is all those things which are
confirmed to such a degree that it would be
unreasonable to withhold one’s provisional
consent.
Stephen Jay Gould
The title of one of Carl Sagan’s books:
The Demon-Haunted World: Science as a
Candle in the Dark
Science is
A way of thinking that is both imaginative and
disciplined;
A balance between openness to new ideas and
skepticism of claims unsupported by evidence;
Based on the facts, even if they don’t
conform to our preconceptions;
Self-correcting. Science is an area of knowledge
that comes with a built in error-correcting
mechanism, and demands that scientific ideas be
open to scrutiny by the “outside world”
Whenever scientific findings are published, the
data is accompanied by error bars, describing
how well we trust what we think we know.
If the error bars are small, we
have a greater confidence that
the data is reliable and reflects
how the world really is.
The larger the error bars, the
more variable the data and the
less confident we are that a true
relationship exists. The data
may be suggestive, but further
confirmation is needed before
anyone will accept a conclusion
based on such unconvincing
data.
Scientists are very careful in the way
they state their claims to understand
the real world.
Levels of confidence vary from educated guesses
based on observations, called hypotheses, to
scientific laws, which are meant to be simple, true,
absolute and universal.
Scientific theories explain a series of related
hypotheses that have been critically tested multiple
times and withstood all attempts to falsify them.
Rabbits average 6 babies per litter.
OBSERVATION #1: All species have such great
potential fertility that their population size would
increase exponentially if all individuals that are born
reproduced successfully.
The world is not overrun by rabbits.
OBSERVATION #2: Populations tend to remain stable
in size, except for seasonal fluctuations.
There’s only so much food and space available to
rabbits.
OBSERVATION #3: Environmental resources are
limited.
Only some of the baby rabbits survive to
adulthood.
INFERENCE #1: Production of more individuals
than the environment can support leads to a
struggle for existence among individuals of a
population, with only a fraction of offspring
surviving each generation.
No two baby rabbits are exactly alike.
OBSERVATION #4: Individuals of a population vary
extensively in their characteristics; no two individuals are
exactly alike.
Rabbits reproduce sexually which leads to variation
among offspring.
OBSERVATION #5: Much of this variation is heritable.
INFERENCE#3: The unequal ability of individuals
to survive and reproduce will lead to a gradual
change in a population, with favorable
characteristics accumulating over the generations.
Law of Natural Selection:
populations can change over generations if
individuals that possess certain heritable traits
leave more offspring than other individuals, thus
leading to better adaptation of the population to
its environment.
INFERENCE #2: Survival in the struggle for
existence is not random, but depends in part on
the hereditary constitution of the surviving
individuals. Those individuals whose inherited
characteristics best fit them to their environment
are likely to leave more offspring than less-fit
individuals.
Well adapted rabbits contribute more
offspring to the next generation than do less well
adapted rabbits.
Theory of Evolution by Natural Selection
– All species are descended from
preexisting species through the gradual
accumulation of genetic changes
Lines of Evidence
•fossil evidence of species’ change over time
•embryology and conserved DNA sequences
•universal genetic code
•“molecular clock” of DNA
•anatomical evidence of homologous structures
•laboratory and field work with numerous species
To date, there exists no scientifically credible evidence
to falsify the theory of evolution – scientists accept it
as TRUE until evidence emerges to suggest otherwise.
Should scientifically credible evidence appear,
scientists will have to make what is called a
Paradigm shift
Thomas S. Kuhn – The Structure of Scientific
Revolutions
“scientific revolutions necessitated the community’s
rejection of one time-honored scientific theory in favor of
another incompatible with it.
And each transformed the scientific imagination in
ways that we shall ultimately need to describe as a
transformation of the world within which scientific work
was done. Such changes…are the defining characteristics
of scientific revolutions.”
In astronomy:
Ptolemy’s Heliocentric theory – The Copernican
Revolution - Kepler’s Laws of Planetary Motion
In Physics:
Aristotle – Newton’s physics - Einstein’s physics –
Quantum physics and the wave-particle duality of
matter
In Chemistry:
Democritus’ ideas about atoms - Theory of elective
affinity – John Dalton’s atomic theory - Niels
Bohr’s planetary model – Modern electron cloud
model and the Heisenberg exclusion principle
My favorite quote is from Niels Bohr, speaking of
quantum physics:
“If you aren’t confused you haven’t understood it
very well.”
Science requires us to give up our “naïve” notions of
how the world works, in favor of experimentally
demonstrated laws which we understand to be
provisional. These laws are only as good as their
ability to explain the data, that is, our perceptions .
Be open to new ideas, but be skeptical!
•question authority
•ask for the evidence
•consider the background assumptions
•reject pseudoscience – claims presented
in scientific language but not rigorously
tested using scientific methods