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Philosophy and Nature of Science

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Title: Philosophy and Nature of Science


1
Philosophy and Nature of Science
  • Part 1. Philosophy
  • Part 2. Philosophers

2
Basic Questions
  • How do we know?
  • What is knowing?
  • Can we know with certainty?
  • Can we believe something with certainty?
  • Are there facts?
  • Is there truth?
  • Can an hypothesis be verified or falsified?

3
What Constitutes Evidence?
  • Is there a relationship between evidence and
    hypothesis?
  • What evidence does one select to establish an
    hypothesis?

4
How Does One Do SCIENCE?
  • Science does not adhere to the Baconian procedure
    of observation before hypothesis, hypothesis
    before testing.
  • It is more artistically driven. The scientist
    responds to an observed event by curiosity. The
    scientist follows up curiosity with persistence
    having no sure and fixed method to unravel the
    conundrum. Finally the researcher employs memory
    to relate one event to another and to avoid
    redundancy.

5
Questions asked in the philosophy of science
  • Is science based on faith?
  • What is the scientific method?
  • How are new discoveries treated?
  • Is everything reducible to physics and
    mathematics?
  • Is everything reducible to a few rules?

6
Science and Faith
  • Some Articles of Faith
  • Science is based on articles of faith
  • The universe is consistent over space and time.
  • The universe is understandable.
  • We can understand the universe.
  • Whats valid here is valid there.
  • The universe is material and not spiritual
  • The universe is mathematical.
  • Experiment validates theory

7
What Characterizes science?
  • A method for retaining reliable knowledge about
    the universe due to test and retest
  • Science is a testing community
  • Science seeks consistency not truth
  • Science tells the best minimal story about the
    universe. Pieces fit into a puzzle
  • Science does not ask why, but asks how, what,
    where, and when. Science seeks measurement

8
Ideal Scientific Method
  • Observation
  • Repetition
  • Induction(1)
  • Hypothesis
  • Deduction or generalization
  • Consequence or prediction
  • Testing
  • Induction(2)
  • Induction (1) not successful

9
Critique of the Ideal scientific Method
  • Whats observed and studied depends on the
    currently accepted explanation
  • Explanation selects the observation
  • Explanation Influenced by
  • Brain hardware
  • Gestalt formation
  • Optical illusions
  • Brain Software
  • Education

10
Induction
  • induction
  • Observation -----------------gt Hypothesis

11
Induction
  • Induction goes from effect to cause.
  • Effect can possibly have many causes.
  • A cause may have a single effect.
  • Hypothesis is a kind of cause

effect
cause
12
Critique of Induction
  • There is no logical way of going from observation
    to hypothesis
  • Hypothesis is a simple guess
  • Frequently hypothesis precedes observation

13
Hypothesis, Theory, Fact
  • Hypothesis are Guesses not logically derivable
    from deduction or Induction
  • Theories are statement of Probability
  • Facts do not exist- nothing is 100 certain

14
Verification Falsification
  • What is meant by explanation?
  • What is a fact?
  • When is a Fact verified?
  • How many observations needed?

15
Deduction and Induction
  • induction
  • Observation ------------gt Hypothesis
  • deduction
  • Hypothesis ------------gt Observation

16
Deduction
  • If there is no cogent way of going from
    observation to hypothesis
  • Then there is no cogent way of deducing from
    hypothesis to observation

17
Critique of Deduction
  • Modern Science does not seek causes but seeks
    relationship among variables
  • Independent variables are not causes and
    dependent variables are not effects
  • If one knows Y g(x), can one predict (deduce)
    the future?

18
Verification and Falsification
  • Replace Verification with Falsification
  • Verification and falsification are asymmetrical
  • Multiple verification does not establish a theory
    more than a single verification
  • A single falsification overturns a theory
  • It takes only one green swan overturns the
    theory that all swans are white. Observing one
    million white swans does no more to prove all
    swans are white than witnessing ten white swans.

19
Falsification
  • It is nearly impossible to falsify an hypothesis.
  • Since a test depends on many factors it is
    difficult to determine whether the hypothesis
    failed or one of the other factors failed.
  • Some failures of dependent factors
  • precision and accuracy of instrumentation,
    correct interpretation of data, flawless
    recording of data, improper experimental
    conditions

20
Transition to Immanuel Kant
  • Rationalism and Empiricism

21
Historical Overview
Rationalism
Descartes
Spinoza
Leibniz
Wolff
Kant
Locke
Berkeley
Hume
Empiricism
22
Empiricism
  • Basic tenets of Empiricism
  • All knowledge comes from experience
  • The mind is a blank slate (tabula rasa)
  • The mind is passive, merely a receptor of sense
    impressions
  • Humes radicalizes these, ending in Skepticism
  • Unbridgeable gap between sense impressions and
    objects in the world
  • All we know are sensations playing in our minds
  • The necessary connectedness of experience is
    problematic Causality is merely superstition,
    born of habit

23
Rationalism
  • Basic tenets of Rationalism
  • Reason has access to reality as it really is
  • Reason can go beyond what is given to us in
    experience
  • Reason can then grasp things, not as they appear,
    but as they really are
  • The Leibniz-Wolffian School
  • Reason (without experience) can know about God,
    immortality of the soul, and human freedom
  • Reason has direct access to meta-physical
    knowledge

24
Part 2
  • John Locke
  • David Hume
  • Immanuel Kant
  • Thomas Bayes
  • Karl Popper
  • Thomas Kuhn
  • Imre Lakatos

25
John Locke (1632-1704)
  • Introduction

26
John Locke
27
Biography
  • B. 1632, son of a small property-owner and lawyer
  • Oxford, 1652-67
  • Studied church-state issues, chemistry and
    medicine, new mechanical philosophy
  • Involvement in politics through Lord Ashley, whom
    he treated for a liver abscess
  • Plotted to assassinate King Charles II and his
    Catholic brother, later James II
  • Exile in Holland, 1683-89
  • 1689 3 major works published

28
Major works and themes
  • A Letter Concerning Toleration (1689)
  • Argues for religious toleration
  • Except for atheists, who deny the Being of a
    God and thus cannot be trusted to keep their
    promises (e.g. in contracts).
  • Context
  • - Religious wars and persecution in England and
    on the Continent.

29
Works, cont.
  • Essay Concerning Human Understanding (1689)
  • Argues against innate ideas
  • For the acquisition of knowledge through the
    senses Intuitionism
  • Anti-Cartesian (Descartes)
  • Re-opens debate about essentialism vs
    conventionalism with his views on identity,
    comparison, classification and natural kinds.

30
Works, cont.
  • Two Treatises on Government (written 1679/80
    published 1689/90)
  • First Argues against traditional basis for
    political authority expressed in Filmers
    Patriarcha, divine right of kings
  • Second protection of private property, life and
    liberty basis for civil government.

31
Lockes Basic Epistemology
  • Human being tabula rasa (blank slate)
  • receives sense-impressions
  • some of these transformed by Mind into Ideas
  • Ideas represented in language by words
  • However, no Ideas are innate
  • Mind operates (through gradual learning process)
    w/out reference to any received authority (of
    Church, State or others)

32
Complex Ideas
  • Sense-data of primary qualities (PQs) and
    secondary qualities (SQs), produce ideas in the
    mind
  • Ideas are mental results of sense-data
  • -Sense-perceptions
  • -Bodily sensations
  • -Mental images
  • -Thoughts and concepts

33
Primary(PQ) and Secondary Qualities(SQ)
  • Distinction between perceived aspects of things.
    The primary qualities are intrinsic features of
    the thing itself (its size, shape, internal
    structure, mass, and momentum, for example),
    while the secondary qualities are merely its
    powers to produce sensations in us (its color,
    odor, sound, and taste, for example). This
    distinction was carefully drawn by Galileo,
    Descartes, Boyle, and Locke, whose statement of
    the distinction set the tone for future
    scientific inquiry. But Foucher, Bayle, and
    Berkeley argued that the distinction is
    groundless, so that all sensible qualities exist
    only in the mind of the perceiver.

34
Attacks Innatism (Descartes)
  • Lockes objections to innate ideas (IIs)
  • Lack of universal assent IIs not known to
    idiots, children, illiterates
  • Dependence on authority
  • a Man is not permitted without Censure to
    follow his own Thoughts in the search of Truth,
    when they lead himout of the common Road.
  • Epistemological and political commitment to the
    individual (who is the foundation of Lockes
    political liberalism).

35
David Hume(1711-1776)
Revised, 11/21/03
  • An Inquiry Concerning Human Understanding

36
Anthem1
Anthem2
37
1. Sensation the Origin of Ideas
  • The contents of the mind (1) ideas (2)
    impressions (sensations feelings) -- Ideas
    (concepts, beliefs, memories, mental images,
    etc.) are faint unclear impressions are strong
    vivid.
  • Ideas are derived from impressions All ideas
    are copies of impressions.
  • The meaning of ideas depends on impressions

38
The empirical criterion of meaning
  • "From what impression is that alleged idea
    derived?"

No impression, no meaning? No impression, no
foundation in reality?
39
The Nature Limits of Human Knowledge
40
Two kinds of ideas(or judgments)
"All the objects of human reason or inquiry may
naturally be divided into two kinds relations
of ideas and matters of fact".
"Hume's Fork"
41
Judgments concerning relations of ideas
Ideas
("Hume's Fork")
Judgments concerning matters of fact
42
Judgments concerning relations of ideas
  • Intuitively or demonstrably certain
  • Discoverable by thought alone a priori
  • Cannot be denied without contradiction

Hume's examples Pythagorean Theorem
or
3 x 5 30 ? 2
43
On a right triangle, the square of the hypotenuse
is equal to the sum of the squares of the other
two sides
The Pythagorean Theorem
5'
4'
(hypotenuse)
32 42 52 (9 16 25)
3'
44
Judgments concerning matters of fact
  • "Every judgment concerning matters of fact can be
    denied without contradiction" (e.g., "the sun
    will not rise tomorrow").
  • Neither intuitively nor demonstrably certain
  • Not discoverable by thought alone a priori, but
    rather on the basis of sense experience a
    posteriori

More specifically,
45
All judgments concerning matters of fact are
based on . . . .
  • the more fundamental belief that there is "a tie
    or connection" between cause effect.

46
And why do we believe that there is a "tie or
connection" between cause effect?
Answer The belief arises entirely from
experience a posteriori, not a priori, namely,
the experience of finding that two events (cause
effect) are "constantly conjoined" with each
other.
47
It is not logically necessary that a particular
effect follows a particular cause
  • it is just a fact of experience.

This view leads to Hume's discussion of . . . .
48
3. The Nature Limits of Inductive Reasoning
  • (the problem of induction)

49
Hume on Induction
  • Induction is the process of drawing inferences
    from past experiences of cause effect sequences
    to present or future events.
  • Hume's point is that an "effect" cannot be
    validly deduced from its "cause"
  • the inference from "cause" to "effect" is based
    on past experiences of "constant conjunction,"
    and these past experiences . . . .

50
accustom or habituate us
  • to believe that one event is the cause of
    another, which we believe to be the effect of the
    prior event.

This is what leads us to believe that . . . .
51
the future will resemble the past.
  • It is all a matter of CUSTOM or HABIT.

This is the foundation of . . . .
52
The Idea that there is a Necessary Connection
between Cause Effect
If this is a meaningful ( true?) idea, then
(according to Hume) it must be derived from sense
impressions.
What, then, is the sense impression from which
this idea is derived?
53
There is no sense impression of causal power or
necessary connection of cause effect, but we do
experience . . . .
  • (1) the spatial contiguity,
  • (2) the temporal succession, and
  • (3) the constant conjunction

of "cause" "effect."
54
It is from this experience,
  • especially the experience of constant
    conjunction,
  • that the idea of a necessary connection between
    "cause" "effect" arises (or is inferred)
  • but the "inference" is simply a matter of "custom
    or habit."
  • This seems to mean that the "inference" here is
    psycho-logical rather than logical. Actually,
    there is no experience of the necessary
    connection between cause and effect. Thus, all
    factual judgments (which are based on the
    assumption that there is a necessary connection
    between cause and effect) are subject to doubt.
  • No necessity, no certainty.

55
Immanuel Kant
1724-1804 Lutheran (Pietist) background
Second Copernican Revolution in philosophy
Spent all his life in Königsberg, a small German
town on the Baltic Sea in East Prussia. (After
World War II, Germany's border was pushed west,
so Königsberg is now called Kaliningrad and is
part of Russia.)
Groundwork of the Metaphysics of Morals
56
Immanuel Kant
At the age of fifty-five, Kant had published
much work on the natural sciences, taught at
Königsberg University for over twenty years, and
achieved a good reputation in German literary
circles. During the last twenty-five years of
his life, however, Kant's philosophical work
placed him firmly in the company of such towering
giants as Plato and Aristotle.
Groundwork of the Metaphysics of Morals
57
Immanuel Kant
Kant's three major works are often considered
to be the starting points for different branches
of modern philosophy the Critique of Pure
Reason (1781) for the philosophy of mind the
Critique of Practical Reason (1788) for moral
philosophy and the Critique of Judgment
(1790) for aesthetics.
Groundwork of the Metaphysics of Morals
58
Immanuel Kant
The Grounding for the Metaphysics of Morals was
published in 1785, just before the Critique of
Practical Reason. It is essentially a short
introduction to the argument presented in the
second Critique.
Groundwork of the Metaphysics of Morals
59
Kants Intellectual Climate
Kant lived and wrote during the Enlightenment.
This period produced the ideas about human rights
and democracy that inspired the French and
American revolutions. (Some other major figures
of the Enlightenment were Locke, Hume, Rousseau
and Leibniz.) The characteristic quality of
the Enlightenment was an immense confidence in
reason, i.e. humanity's ability to solve problems
through logical analysis. The central metaphor of
the Enlightenment was a notion of the light of
reason dispelling the darkness of mythology and
misunderstanding.
Groundwork of the Metaphysics of Morals
60
Kants Intellectual Climate
Enlightenment thinkers like Kant felt that
history had placed them in the unique position of
being able to provide clear reasons and arguments
for their beliefs. The ideas of earlier
generations, they thought, had been determined by
myths and traditions their own ideas were based
on reason.
Groundwork of the Metaphysics of Morals
(According to this way of thinking, the French
monarchy's claims to power were based on
tradition reason prescribed a republican
government like that created by the revolution.)
61
Kant
Kant's philosophical goal was to use logical
analysis to understand reason itself. Before we
go about analyzing our world, Kant argued, we
must understand the mental tools we will be
using. In the Critique of Pure Reason, Kant
set about developing a comprehensive picture of
how our mind our reason receives and
processes information.
Groundwork of the Metaphysics of Morals
62
Kant
Kant later said that the great Scottish
philosopher David Hume (1711-1776) had inspired
him to undertake this project. Hume, Kant said,
awoke him from an intellectual "slumber." The
idea that so inspired Kant was Hume's analysis of
cause-and-effect relationships.
Groundwork of the Metaphysics of Morals
63
Hume
According to Hume, when we talk about events in
the world we say that one thing causes another.
But nothing in our perceptions tells us that
anything causes anything else. All we know from
our perceptions is that certain events regularly
occur immediately after certain other events.
Causation is just a concept that we employ to
make sense of why certain events regularly follow
certain other events.
Groundwork of the Metaphysics of Morals
64
Kant
Kant took Hume's idea and went one step
further. Causation, Kant argues, is not just an
idea that we employ to make sense of our
perceptions. It is a concept that we cannot help
but employ. We don't sit around watching events
and then develop an idea of causation on the
basis of what we see. We automatically bring the
concept to bear on the situation.
Groundwork of the Metaphysics of Morals
65
Kant
Kant argued that causation and a number of
other basic ideas (e.g., time and space) are
hardwired, as it were, into our minds. Anytime we
try to understand what we see, we cannot help but
think in terms of causes and effects.
Groundwork of the Metaphysics of Morals
66
Kant
Kant's argument has huge implications. If our
picture of the world is structured by concepts
that are hardwired into our minds, then we can't
know anything about how the world really is.
The world we know about is developed by
combining sensory data (appearances or
phenomena, as Kant called them) with
fundamental concepts of reason (causation,
etc.). We don't know anything about the
things-in- themselves from which sensory data
emanates.
Groundwork of the Metaphysics of Morals
67
Kant
This recognition that our understanding of the
world may have as much to do with our minds as
with the world has been called a Copernican
Revolution in philosophy a change in
perspective as significant to philosophy as
Copernicuss recognition that the earth is not
the center of the universe.
Groundwork of the Metaphysics of Morals
68
Kant
Kant's insights posed a severe challenge to
many earlier ideas. Ex. Before Kant many
philosophers offered proofs of the existence
of God. One argument made was that there must be
a "first cause" for the universe. Kant pointed
out that the question of whether there "must" be
a first cause for the universe is irrelevant,
because it is really a question about how we
understand the world, not a question about the
world itself.
Groundwork of the Metaphysics of Morals
69
Kant
Kants analysis similarly shifted the debate
over free will and determinism. (Kant presents a
version of this argument in Chapter 3 of the
Groundwork.) When we use reason to understand
why we have made the choices we have, we can
come up with a causal explanation. But this
picture is not necessarily accurate. We don't
know anything about how things "really" are we
are free to think that we can make free choices,
because for all we know this might "really" be
the case.
Groundwork of the Metaphysics of Morals
70
Kant
In the Critique of Practical Reason and the
Grounding for the Metaphysics of Morals, Kant
applies this same technique using reason to
analyze itself to determine what moral choices
we should make. Just as we cannot rely on our
picture of the world for knowledge about how the
world "really" is, so also we cannot rely on
expectations about events in the world in
developing moral principles. Kant tries to
develop a moral philosophy that depends only on
the fundamental concepts of reason.
Groundwork of the Metaphysics of Morals
71
Kants Intellectual Climate Criticisms
Some later thinkers have criticized Enlightenment
philosophers like Kant for placing too much
confidence in reason. Some have argued that
rational analysis is not the best way to deal
with moral questions. Further, some have argued
that Enlightenment thinkers were pompous to think
that they could discover the timeless truths of
reason in fact, their ideas were determined by
their culture just as all other peoples are.
Groundwork of the Metaphysics of Morals
72
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73
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74
Karl Popper
  • Popper replaces induction with falsification
  • Science is not distinguished from non-science on
    basis of methodology. No unique methodology
    specific to science
  • Science consists mostly of problem solving.

75
Karl Popper
  • All observations are selective and theory laden
  • A demarcation between science and pseudo-science
    is established by falsification. A theory is
    scientific only if it is refutable by a
    conceivable event
  • Every genuine test of a scientific theory is
    based on an asymmetry between verification and
    falsification

76
Sir Karl Popper (1902-1994)
  • Falsification is the idea that science advances
    by unjustified, exaggerated guesses followed by
    unstinting criticism.
  • Any "positive support" for theories is both
    unobtainable and superfluous all we can and need
    do is create theories and eliminate error
  • Scientists never actually use induction. It is
    impossible to verify propositions by reference to
    experience

77
Falsificationism (1)
  • Scientific Method
  • Is there a scientific method?
  • What justifies scientific claims to knowledge?
  • Can we distinguish scientific method from
    non-scientific ways of thinking? (demarcation)
  • Does science progress?

78
Falsificationism (1)
  • Falsificationism No criterion of truth
  • Two Arguments
  • No Theory/observation distinction
  • Here is a glass of water is theory laden
  • In accepting the statement we must accept a
    significant amount of theory
  • We have only as much justification for accepting
    the observation statement as we do for the theory

79
Falsificationism (1)
  • Falsificationism No criterion of truth
  • Two Arguments
  • No Theory/observation distinction
  • Upshot we cannot use observation to
    establish the truth of a theory
  • How can we establish the truth of scientific
    theories?
  • We cant!

80
Falsificationism (1)
  • Confirmation and Pseudoscience
  • Good scientific practice
  • E.g. Einsteins general relativity
  • Conjecture mass of the sun bends the path of
    light

Apparent location
Actual location
81
Falsificationism (1)
  • Confirmation and Pseudoscience
  • Good scientific practice
  • E.g. Einsteins general relativity
  • Conjecture mass of the sun bends the path of
    light
  • If the apparent location of the observed star
    doesnt shift, the theory is wrong.
  • It will have been refuted.
  • The mark of a scientific theory is whether it can
    be falsified by observation

82
Falsificationism (1)
  • Conjecture and Refutation
  • Falsificationists prefer an attempt to solve
    an interesting problem by a bold conjecture,
    even (and especially) if it soon turns out to
    be false, to any recital of a sequence of
    irrelevant truisms (CR 231)
  • This gives us
  • (i) a glimpse of scientific method
  • (ii) a demarcation criterion for science

83
Falsificationism (1)
  • Scientific method
  • Scientific theories have deductive consequences
  • They can be falsified but not confirmed.
  • The objective of scientific theorizing is to put
    forward (bold) hypotheses and then test them in
    order to falsify them
  • Theories are falsified by basic statements
  • (what is a basic
    statement?)

84
Falsificationism (1)
  • Demarcation
  • Scientific theories are those that can be
    falsified by basic statements.
  • Good scientific theories do not make themselves
    immune from falsification by use of ad hoc
    hypotheses

85
Falsificationism (1)
  • Progress of Science
  • Science progresses by eliminating theories that
    have been falsified?
  • But does it progress?
  • A scientific theory cannot be shown to be true.
    But some scientific theories do have varying
    degrees of success. They resist falsification.

86
Falsificationism (1)
  • We must not look upon science as a body of
    knowledge, but rather as a system of
    hypotheses which in principle cannot be
    justified, but with which we work as long as they
    stand up to tests, and of which we are never
    justified in saying that we know that they are
    true, or more or less certain or even
    probable

87
Kuhn (1)
  • Thomas Kuhn
  • (1922-1996)
  • The Copernican Revolution (1957)
  • The Structure of Scientific Revolutions (1962)
  • History of science not compatible with
    rationalist view
  • Progress of science not cumulative, driven by the
    application of a method

88
Kuhn (1)
  • Thomas Kuhn
  • (1922-1996)
  • The Copernican Revolution (1957)
  • The Structure of Scientific Revolutions (1962)
  • No obvious science/non-science demarcation
  • No context of discovery/context of justification
    distinction

89
Kuhn (1)
  • Kuhns History of Science
  • Two projects
  • Descriptive what is the structure of scientific
    history?
  • Normal science Scientific revolution
  • Explanatory why does the history of science
    have this structure?
  • Paradigms

90
Kuhn (1)
  • 1. Kuhns History of Science
  • Descriptive Project

Immature Science
Revolution
Normal Science
Crisis
Anomalies
91
Paradigm Diagram
  • old paradigm unexplained observations
    competing new

paradigms
incommensurate
one dominant paradigm
puzzle solving
Mopping up operation
unsolved puzzles ignored
unexplained observations
unexplained observations and alternative
interpretation ignored until enough accumulates
to overturn current paradigm
92
Kuhn (1)
  • 1. Kuhns History of Science
  • Immature Science
  • No prevailing school of thought
  • Various disparate theories
  • Competition

93
Kuhn (1)
  • 1. Kuhns History of Science
  • Normal Science
  • Stability
  • Determination of significant facts
  • Matching facts with theories
  • Articulation of theories (refinement and
    extension)
  • puzzle -solving neither tests nor confirms its
    theories

94
Kuhn (1)
  • 1. Kuhns History of Science
  • Normal Science
  • Driven by a paradigm (more later)
  • Commonly held set of beliefs, procedures,
    techniques
  • Agreement upon questions of import
  • Agreement on what counts as a solution
  • Agreement upon standards of evaluation

95
Kuhn (1)
  • 1. Kuhns History of Science
  • Anomalies
  • Not all expectations are borne out
  • Some anomalies lead to further discoveries (e.g.
    orbit of Uranus)
  • Some simply ignored
  • Troublesome anomalies
  • Challenge key theoretical concepts
  • Resist solutions
  • Inhibit application of theory

96
Kuhn (1)
  • 1. Kuhns History of Science
  • Crisis
  • Weight of accumulated anomalies
  • No agreement on how anomalies are to be dealt
    with
  • Doubts arise

97
Kuhn (1)
  • 1. Kuhns History of Science
  • Revolution
  • A new paradigm emerges
  • Old Theory well established, many followers,
    politically powerful, well understood, many
    anomalies
  • New Theory few followers, untested, new
    concepts/techniques, accounts for anomalies, asks
    new questions

98
Kuhn (1)
  • 1. Kuhns History of Science
  • Revolution
  • A new paradigm emerges
  • Are old and new theories compared by some
    rational procedure?
  • A new scientific theory does not triumph by
    convincing its opponents and making them see the
    light, but rather because its opponents
    eventually die, and a new generation grows up
    that is familiar with it (Planck)

99
Kuhn (1)
  • Scientific Revolutions

The Ptolemaic model
The earth is at the centre of the planetary
system Problem How to explain the retrograde
motion of planets
100
Kuhn (1)
  • Scientific Revolutions

The Ptolemaic model
The earth is at the centre of the planetary
system Problem How to explain the retrograde
motion of planets
Deferent
Earth
Planet
Epicycle
101
Kuhn (1)
  • Scientific Revolutions

The Ptolemaic model
http//csep10.phys.utk.edu/astr161/lect/retrograde
/aristotle.html
The earth is at the centre of the planetary system
102
Kuhn (1)
  • Scientific Revolutions
  • The Ptolemaic Model
  • Problems
  • Complexity epicycle upon epicycle
  • The accumulation of anomalies
  • No clear way forward

103
Kuhn (1)
  • Scientific Revolutions

The Copernican model
The sun is at the centre of the planetary
system Problem How to explain the retrograde
motion of planets
104
Kuhn (1)
  • Scientific Revolutions

The Copernican model
http//csep10.phys.utk.edu/astr161/lect/retrograde
/copernican.html
The sun is at the centre of the solar system
105
Kuhn (1)
  • Scientific Revolutions
  • The Copernican Revolution was not the consequence
    of an old theory with less empirical content
    being replaced by a new theory with more
  • No appeal to reason alone
  • propaganda
  • To discover how scientific revolutions are
    effected, we shall therefore have to examine
    the techniques of persuasive argumentation within
    the quite special groups that constitute the
    community of scientists (SSR 94)

106
Kuhn (1)
  • 2. Explanatory Project
  • Two Questions
  • If this is the course of the history of science,
    why?
  • Why arent competing theories/traditions measured
    against each other by some rational procedure?

107
Kuhn (1)
  • 2. Explanatory Project
  • Paradigms
  • Disciplinary Matrix
  • (i) Symbolic generalisations
  • (ii) Metaphysical commitments
  • (iii) Scientific values
  • (iv) Heuristic models
  • (v) Exemplars

108
Kuhn (1)
  • Explanatory Project
  • Why is normal science stable?
  • It is conducted wholly within the terms of a
    disciplinary matrix
  • questions
  • procedures
  • problems
  • priorities
  • standards of evaluation
  • All are generated by the disciplinary matrix

109
Kuhn (1)
  • Explanatory Project
  • Why is theory change revolutionary?
  • Theory change is brought about by a gestalt
    switch a complete change of world view
  • There is no neutral point from which one can
    assess theories from two paradigms simultaneously

110
Thomas Kuhn (1922-1996)
  • All research presupposes a world-view,a
    collection of fundamental objects, natural laws,
    definitions, and above all a definition of what
    research is.
  • Kuhn called a world-view, paradigms
  • Mature science have established paradigms
  • Example of mature sciences are chemistry,
    physics, geology whereas, economics and
    psychology are
  • immature sciences.

111
Paradigm
  • Thomas Kuhn popularized the term in his book The
    Structure of Scientific Revolutions (1996) by
    using it to describe how science works. According
    to Kuhn, scientific explanations of the world are
    controlled by a paradigm, some model of how the
    world is expected to work and into which actual
    observations are fitted, even if the fit is not
    very exact. As inexact fits accumulate, it
    becomes more apparent that the dominant paradigm
    is inadequate as a model of reality. When enough
    contradictions exist, a paradigm revolution
    occurs and a new paradigm is adopted.
  • The word paradigm comes from the Greek
    paradeiknunai and means "to compare." In science
    and philosophy it has the same basic meaning as
    in common usage a model or instance used as a
    basis or example for further work.

112
Need for Paradigms
  • Research requires paradigms
  • Paradigms are models of the way the world works
  • Without paradigms research is a random collection
    of observations lacking unification of structure
    into a whole.
  • Without paradigms, it is not possible to decide
    which are and which are not important
    observations

113
Dominant Paradigms
  • As a field matures, one paradigm becomes the
    dominant one. Once paradigms is established
    research progresses quickly

114
Paradigm guides direction of Research
  • It becomes clear with aid of paradigm which
    research areas are fruitful. These areas are ones
    not totally explained
  • Paradigms give concepts and laws to build on.

115
Paradigm Shift
  • Paradigm shift occurs when old paradigm shown
    inadequate
  • What is defined as research is reevaluated
  • Concepts turn upside down. Earlier research is
  • reinterpreted

116
Real research
  • Real Research occurs during a paradigm shift
  • Once a paradigm dominates, research becomes
    puzzle solving
  • Puzzle solving is not research due to answers
    known beforehand

117
Example of Puzzle Solving
  • After Newton explained solar system, later
    scientists using Newtons theory predicted
  • The presence of the then unknown planets
  • Neptune, Uranus, and Pluto

118
What New Paradigms Do
  • Discovery of new paradigm results in new
    questions being asked and old questions abandoned
  • Newton saw gravitation as a property of matter.
    Earlier theories tried to find a mechanical
    explanation as whirlpools in space or angels.

119
Paradigms are Incommensurable
  • Paradigms have different world view. It is
    difficult to compare them
  • Consequently, science defines truth relative to a
    paradigm and not absolutely. Truth is a story

120
Science
  • Science is a conformist society which present
    only the currently accepted theory
  • Consequently science defines reality relative to
    the accepted paradigm
  • Students are educated into the accepted paradigm
    and to ignore alternative paradigms
  • The society of science determines what scientists
    observe

121
Imre Lakatos (1922 - 1974)
  • All scientific theories are equally un-provable
  • Falsification doesnt work due to rescue
    hypotheses
  • the "basic unit" of scientific development is not
    the scientific theory, such that science
    progresses when one theory proves to be more
    successful than another.

122
Imre Lakatos
  • the "basic unit" is actually the research
    program. Science progresses when one research
    program becomes more productive and more useful
    than other and, hence, receives a greater share
    of social resources through funding and younger
    scientists looking to join. A research program is
    characterized by a particular set of "hard core"
    fundamental ideas and is deemed successful so
    long as it contents continue to increase.

123
Imre Lakatos
  • In reality scientists do not abandon theories.
    They invent rescue hypotheses or ignore
    anomalies or refutations
  • Popperian crucial experiments and Kuhnian
    revolutions turn out to be myths. What happens
    is progressive research replaces degenerating
    ones.
  • Progressive scientific programs predict and
    produce dramatic, unexpected observations and
    results

124
Falsificationism
  • Popper
  • Science progresses toward its goal of increasing
    verisimilitude by advancing bold conjectures and
    then attempting to refute these by observations
  • Theories cannot be verified by observation
  • anti-inductivism
  • no theory/observation distinction
  • Theories are falsified by basic statements
  • We choose between theories on grounds of
    corroboration (mark of verisimilitude)

125
Falsificationism
  • Problems for Falsificationism (recap)
  • Falsification
  • Some legitimate features of scientific enterprise
    are not falsifiable
  • Probabilistic Statements
  • Existential Statements
  • Metaphysical Commitments

126
Falsificationism (finale)
  • Problems for Falsificationism
  • 3. Basic Statements
  • Theories are falsified by basic statements.
  • What warrants our acceptance of basic statements?
  • (i) Observation? No. Basic statements are
    theory laden. Accepting them requires accepting
    theory
  • (ii) Decision/convention not grounded in a
    rational procedure

127
Falsificationism (finale)
  • Whiff of Inductivism
  • A Dilemma for Popper
  • Give up on induction
  • No rational criterion for choosing between
    competing theories
  • No rational grounds for continuing to use
    successful theories
  • Give up the distinctive features of
    falsificationism

128
Falsificationism (finale)
  • Problems for Falsificationism
  • 3. Basic Statements
  • Theories are falsified by basic statements.
  • What warrants our acceptance of basic statements?
  • (i) Observation? No. Basic statements are
    theory laden. Accepting them requires accepting
    theory
  • (ii) Decision/convention not grounded in a
    rational procedure

129
Scientific Research Programmes
  • Revision versus Ad hoc Hypotheses
  • Two questions
  • In the light of anomalies
  • What should one change?
  • Principle of least change
  • (ii) When should one abandon a theory(in favour
    of another)?

130
Scientific Research Programmes
  • Scientific Research Programmes (SRP)
  • A theory is
  • Rules of logic and mathematics
  • Metaphysical commitments
  • Statements of laws
  • Assumptions about initial conditions
  • A SRP is a lineage of theories. SRP evolve over
    time
  • Rules according to which SRPs evolve over time.

131
Scientific Research Programmes
  • Scientific Research Programmes (SRP)
  • Parts of a SRP

Hard Core Theoretical assertions Metaphysical
commitments
HC
Auxiliary Belt Initial conditions Assumptions Ad
hoc hypotheses
AB
132
Scientific Research Programmes
  • Scientific Research Programmes (SRP)
  • Parts of a SRP

e.g. Celestial Mechanics
Hard Core Laws of Motion Universal
Gravitation Space and time
HC
Auxiliary Belt Number of planets Masses of
planets
AB
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