lecture 1 - the basis for the scientific method
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7/30/2019 Lecture 1 - The Basis for the Scientific Method
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Lund University, Lund, Sweden
Department of Water Resources Engineering
On the importance of the wordErgo
Intro to some of fundamentals in the Scientific
Methodology
Presentation at TPU October/November 2012
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The six virtues of science
About the value of arguments
Deduction and Induction
Occams razor Bayes rule
The art of making 1 + 1 = 3
The Menu
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The Six Main Virtues of Science/Rationality:
Curiosity (if you dont ask questions you will never get any answers)
Scholarship (study many sciences and absorb their power as your own)
Realism/Humility (to be humble is to take specific actions in anticipation ofyour own errors)
Empiricism (the roots of knowledge are in observation and its fruit is prediction)
Precision (better be precisely wrong than vaguely right)
Argument/Rational reasoning (Normatively, any argument relieson an evidential base which consists of supporting data whose relationship to the claim iselaborated through the warrant, which in turn, may be dependent on a set of underlyingassumptions)
Fundamentals in the Scientific Methodology
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< Statement or Proposition >
[BECAUSE]
Karena Omdat
Porque
Fordi
Because/Therefore
Ergo
Fundamentals in the Scientific Methodology
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Possible arguments:
The Earth is Flat as a Pancake!
The Earth is Flat as a Pancake BECAUSE the pope
dictates so and will kill me if I say otherwise....
The Earth is Flat as a Pancake BECAUSE I cantunderstand why it could be spherical....
The Earth is Flat as a Pancake BECAUSE my eyes tellme that it looks flat....
Fundamentals in the Scientific Methodology
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Picture from a 1550 edition of On the Sphere ofthe World, the most influential astronomytextbook of 16th century Europe
The Earth is flat because:1. The space agencies of the world are involved in an
international conspiracy to dupe the public for vast profit2. The impossibilities of holding unsecured objects in place
on a curved surface
Fundamentals in the Scientific Methodology
Aristotle (384322 BC), the famous Greek
natural philosopher, reports thatmathematicians had allegedly evaluatedthe dimension of Earth at 40.000 stadia,adding:From their supposition, it followsthat the shape of Earth must be a sphereand also that its size be small relative tothe distance of other celestial bodies.
Images of the earth how it wasseen (by the catholic church)during the dark middle age (1000-1500 BC)...
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The two main approaches in modern science:
Deduction (general theories predictions):inference by reasoning from generals toparticulars, or the process of deducing from
something known or assumed
Induction (observations general theories): theprocess of inferring a general law or principle
from observation of particular instances...
Sherlock Holmes (The Sign of Four):I never guess. It is a capital mistake to
theorize before one has data. Insensibly onebegins to twist facts to suit theories, instead
of theories to suit facts.
Fundamentals in the Scientific Methodology
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Occams Razor (looking for the simplestexplanation with the fewest assumptions)
"We are to admit no more causes ofnatural things than such as are both trueand sufficient to explain their
appearances"
"If you have two theories that bothexplain the observed facts, then youshould use the simplest until moreevidence comes along" KISS...!
Keep It Simple, Stupid!
"The explanation requiring thefewest assumptions is mostlikely to be correct"
Fundamentals in the Scientific Methodology
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Bayes Rule (accummulating (uncertain) evidence againstan (uncertain) hypothesis)
The essence of the Bayesian approach is to provide:a mathematical rule explaining how you should change
your existing hypothesis in the light of new evidence.In other words, it allows scientists to combine new data withtheir existing knowledge or expertise
A(Hypothesis)
B(Data)
Fundamentals in the Scientific Methodology
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Example: Evaluating the Posterior Probabilityof thehypothesis that the Earth is a sphere...
10%
20%
30%
40%
50%
60%
70%
80%
90%
55% 60% 65% 70% 75% 80% 85% 90% 95%
Likelihoodofobservin
gX
given
A
Prior probability of A
80%-100%
60%-80%
40%-60%
20%-40%
0%-20%
Fundamentals in the Scientific Methodology
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Example: Updating the Posteria Probabilitywithrepeated/improved observations
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1 2 3 4 5 6 7Posteriaprobability
thatourtheory(A)istrue
Experiment no
Bayes' Rule - Opdating of Theory via Observations
P(X|A) - L ikelihood of obs P(A|X) - probability that theiry is true
FALSIFICATION....!
Fundamentals in the Scientific Methodology
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Hegels dialectical method or the principle ofdeduction by counter argument (towards the one and onlythruth.....)
Thesis Anti-Thesis
Syn-Thesis
Anti-Thesis
Syn-Thesis
Fundamentals in the Scientific Methodology
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...sometimes it is a constructive approach:(union set = improvement/generalisation of theory = both-and)
EinsteinEinsteins general
relativity theory
Newtons
theorythe three
basiclaws
Space
Time
Newton
Fundamentals in the Scientific Methodology
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...but it does not always work(as so many theories...)
The Earth is spherical....!The Earth is Flat....!
Disjunction set: Shift in paradigm = either or
Fundamentals in the Scientific Methodology
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Finale:
Scienceis a process of learning to know thenature of everything in the material world, fromatoms to the most complex of living organisms
and inanimate objects... Scienceis not a Belief it is a methodology! No
more, no less...
Terima Kasih
Fundamentals in the Scientific Methodology
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Break
Examples.....
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