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Philosophy of Science

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Title: Philosophy of Science


1
Philosophy of Science
  • Class 8

2
Admin
  • Teacher Evaluation
  • Pick up midterms
  • Outline/Topic Summary available at my office
    hours tomorrow

3
Classic Tradition
  • The 1950s and 1960s marked the high point of
    what is commonly referred to as the classical
    tradition in science.
  • What is this classical tradition?
  • It is a certain basic view of the world and of
    science which has been shared, to some extent by
    all of the philosophers of science we have
    considered so far.

4
Assumptions of the Classical Tradition
  • There is an outside world, which exists
    independent from all observers.
  • The ultimate goal of science is an accurate (as
    possible) description of this observer
    independent world.
  • Scientists can observe the objective natural
    world, in some way, and learn about it.
  • the universe has underlying regularities that,
    if discovered can explain the behaviour of the
    universe.

5
General Agreement that
  • There is independent observation (if you had
    twenty scientists observing something, they would
    see it about the same).
  • Observation is not dependent on the particular
    observer, and deductive logic is not dependent on
    the observer.
  • Reality is also independent of any particular
    observer.

6
Their important conclusion
  • Science is Objective!

7
This is good because
  • It means we can use science to find out the truth
    about reality!

8
A Requirement of Science?
  • The question is
  • if you lose any of these assumptions, is it still
    possible to even do science?
  • In other words, can you be a scientist if you
    dont believe in
  • An objective reality
  • A reality with causal universal laws
  • An objective observer (or collectively, a group
    of objective observers) who are able to draw
    objective conclusions from objective observations
    of reality.

9
Two branches of Twentieth Century Philosophy of
Science
  • Branch One Logical Positivists, Popper
  • Branch Two Duhem-Quine Thesis, Kuhn
  • Branch Two- stayed focused on the issue of
    whether or not theoretical entities actually
    exist.
  • (Both interested in truth of hypotheses)

10
To say that a statement is true is to say that it
accurately describes reality.
11
Reality of Unobservable Entities
  • Suppose your theory has predictive power
  • How could it have predictive power, if the
    entities didnt actually exist?
  • The predictive power of theories provides
    independent objective proof of the reality of
    unobservable entities

12
16th-20th century Adequate Justification
  • Scientific methods, scientific theories seemed to
    be working!
  • Science was progressing
  • Just before the start of the 20th century- it
    looked like science was on the verge of figuring
    everything out!
  • And then

13
Some problematic theories
  • General Theory of relativity
  • Quantum Electrodynamics
  • Heisenbergs Uncertainty Principle

14
Quantum Electrodynamics
  • The wave theory of light, the corpuscle theory of
    light
  • ? Science came up with very convincing evidence
    that stated that light travelled in waves.
  • ? It also became apparent, that evidence for the
    corpuscle theory of light could not be explained
    by the wave theory.
  • Eventually Einstein declared that , somehow,
    light behaved as both a wave and a particle.

15
Conventionalism(Henri Poincaré (1854-1912),
Pierre Duhem (1861-1916))
  • The problem
  • ? theoretical statements must be either
    supported or refuted with indirect tests.
  • ? indirect tests involve (theoretical) auxiliary
    assumptions.
  • ? In the face of contradictory evidence, the
    truth of a theoretical statement can always be
    saved by stating that some auxiliary assumption
    is false (a la Copernicus).
  • ? The only way to test the truth or falsity of
    auxiliary assumptions is through further indirect
    tests.
  • ? But the indirect testing of the auxiliary
    hypotheses will involve more auxiliary
    hypotheses, which will need to be tested...
  • This results in an infinite regress!

16
Conventionalism(Soft Antirealism)
  • The Solution
  • ? There is a great difference between statements
    made based on direct observation and statements
    whose truth is proved indirectly.
  • ? The truth of observational statements can be
    determined through observation.
  • ? However, if you try hard enough it is always
    possible to make any theoretical statement seem
    true
  • Therefore, theoretical statements can never be
    said to be either true or false.

17
What kind of a solution is that!
18
But wait, theres more
  • Science should still use theories!
  • Any number of theories can be found to help us
    manage our observation statements.
  • Theories must be consistent with our
    observations, and help us to make predictions.
  • We need not be concerned with their relation to
    reality.
  • Note Conventionalism is not denying that there
    is a truth of the matter about reality.

19
Conventionalism Tagline
  • Theoretical statements can never be declared as
    true or false. Theoretical statements are merely
    useful in helping us to organize (cope with) our
    observations.

20
Conventionalism sounds great
  • But it has put us on the path to trouble!

21
Duhem-Quine Thesis(Strong Anti-Realism)
  • William Van Orman Quine (1908-2000)
  • However, he took it one step further.
  • ? Poincaré and Duhem had tried to protect
    observation statements from the Auxiliary
    Hypothesis infinite regress.
  • ? They said that observation statements could be
    declared true or false simply by observing them
    (direct testing) and so they were safe from the
    infinite regress that befell statements that
    relied on indirect testing.
  • Quine disagreed. He did not see a difference
    between theoretical and observational statements.

22
Trusting Observations
  • Consider the simple observation my car is
    blue.
  • How would you verify the truth or falsity of this
    statement?

23
Theory of the World
  • In order to verify that the car is really blue,
    you must already have certain beliefs like
  • The true colour of this car is apparent to me
    when the sun is shining, because then the light
    rays correctly reflect and provide me with
    information about the colour of the car.
  • These beliefs are part of a theory about the
    world. (Your own personal theory)
  • Theory? Oh no! Infinite regress!

24
Important Detail!
  • Quine is not saying that the problem is that our
    senses are fallible.
  • Quine is saying
  • All of our direct observations are necessarily
    connected to theory (through our network of
    beliefs)
  • All theory is vulnerable to the auxiliary
    hypothesis problem (as shown by Duhem and
    Poincaré)
  • Therefore- Even our direct observations are
    vulnerable to the auxiliary hypothesis problem.

25
Strong Antirealism Tagline
  • There is no distinction between observation and
    theory. All statements are vulnerable to
    revision. (All statements are neither true nor
    false.)

26
Realism Tagline
  • Scientific theories describe, to some
    approximation, the way nature really is.
    Unobservable entities really do exist.

27
Starting to Challenge Objectivity
  • The antirealism philosophers Picking at
    objectivity
  • Classic tradition scientists can become passive
    receptacles for what the world wishes to reveal.
    (methods of Bacon,Galileo)
  • The antirealists It isn't that simple. We can't
    be passive observers of reality.

28
Subjectivity
  • Reality would be said to be subjective if the
    nature of its existence depended on whether or
    not it was being observed and how it was being
    observed.
  • A person is said to be subjective when their
    observations or perceptions of reality are
    influenced by their own beliefs, desires or
    experiences.
  • For example, whether or not chocolate ice cream
    tastes good is a subjective matter.
  • Not necessarily bad

29
Bad for the Classical Scientists
  • According to the classical tradition
  • Personal Subjectivity is bad for science! (Why?)
  • Scientists must be trained to be objective!
  • This is possible. (Bacon, Galileo)
  • Antirealists are starting to challenge the idea
    that this is possible
  • But what is the alternative? No science?

30
Thomas Kuhn (1922-1996)
  • The Structure of Scientific Revolutions (1962)
  • the assumptions of the classical tradition
    (including the presence of objectivity in
    science) are bad assumptions
  • science works perfectly well in the absence of
    total objectivity.

Physicist, Historian, Philosopher
31
Paradigms
  • According to Kuhn, every scientists approaches
    the world from within a particular framework of
    understanding.
  • Kuhn calls this framework a paradigm.
  • This framework shapes the way the scientist
    perceives the world, and determines, in part, how
    the world is perceived.

32
The origin of personal paradigms
  • Fledgling scientists (i.e. those of you in this
    class who are doing science degrees) gain their
    framework by being exposed to examples of
    applications of the theories.
  • You learn about the meaning of existing
    scientific theories through exposure to these
    examples.
  • Newtons theories (gravity? momentum?). The
    pendulum examples.
  • By seeing how Newtons theories are applied to
    this situation, I learn about the meaning of
    Newtons theories.

33
Exemplars
  • In scientific community, at a given time, has
    certain standard examples of how a theory might
    be applied- i.e. the pendulum examples.
  • Kuhn called these standard examples exemplars.
  • By being exposed to these exemplars, students of
    science come to understand the meaning of a
    theory, and can then go on to use it in novel
    contexts.

34
An Exemplar example
  • The idea of exemplars can be applied to more than
    just scientific theories.
  • Imagine that you want to learn the meaning of the
    word bird.
  • Someone might teach you the meaning of this word
    by taking you to the zoo and showing you
    sparrows, robins, ducks, ostriches and penguins,
    each time stating Thats an example of a bird.
  • Hopefully you will then be able to apply the word
    bird correctly to new types of birds.

35
The origin of paradigms
  • When science begins to investigate a certain
    aspect of nature, there are no paradigms or
    theories.
  • Very quickly however, individuals develop their
    own theories about the natural phenomenon.
  • Over time, these theories become more general and
    comprehensive- they become generic theories
  • Initially, there are a number of competing
    generic theories, but eventually one generic
    theory comes to be favoured by scientists.
  • This generic theory then becomes a paradigm,
    which will be passed on to new scientists in the
    area.

36
The value of paradigms
  • They provide direction and motivation for
    scientists. (e.g. I wonder what effect increased
    gravity has on pendulum behaviour?)
  • Furthermore, they allow scientists who share the
    same paradigm to effectively work together and
    communicate their findings in a consistent and
    comprehensible manner.

37
Using Paradigms
  • Scientists will look for facts relative to and
    try to solve puzzles relative to their paradigm.
  • Scientists will seek out observations that
    support their paradigms.
  • Scientists will try to clarify and expand the
    paradigm by developing precise laws, accurately
    measuring physical constants and applying their
    paradigm to new phenomena not yet specifically
    covered by the paradigm.

38
Paradigm Example
  • Atomic Paradigm
  • Everything is composed of small indivisible
    particles called atoms.
  • Different substances are composed of different
    types of atoms, or, sometimes, different
    combinations of types of atoms.
  • Phlogiston Paradigm
  • Everything is composed of water, air, earth or
    fire, in some combination. (Phlogiston was the
    name given to the essence of fire).
  • Different combinations of these four substances
    lead matter to provoke different sensations in
    people.

39
Applying the two different paradigms
  • look for facts relative to and try to solve
    puzzles relative to their paradigm. Atoms vs.....
    Phlogiston
  • Seek out observations that support their
    paradigms. Atoms vs........ Phlogiston
  • Try to clarify and expand the paradigm by
    developing precise laws, accurately measuring
    physical constants and applying their paradigm to
    new phenomena not yet specifically covered by the
    paradigm. Atoms vs..... Phlogiston

40
Normal Science
  • A particular paradigm will provide scientists
    with both problems to solve and expectations of
    what solutions they will find.
  • Most of the time, this is how science progresses.
    (normal science).
  • However, occasionally, events arise that result
    in an overthrowing of the existing paradigm and
    its replacement with a new paradigm.
  • The new paradigm is often radically different and
    not compatible with the old paradigm.

41
Scientific Anomalies
  • What causes the overthrowing of an existing
    paradigm?
  • Generally speaking paradigms are quite stable. If
    observations or results are not compatible with
    the paradigm they tend to be ignored or their
    relevance diminished in scientific circles.
  • Sometimes, however, an anomaly is so problematic
    that it cant be ignored.

42
Scientific Crisis!
  • Suppose a problem is too large for science to
    just ignore.
  • In this case, scientists might try modifying some
    parts of their existing paradigm (e.g. changing
    or adding auxiliary hypotheses).
  • Every effort will be made to hold onto the
    paradigm.
  • Eventually, however, too many of these anomalies
    may build up, precipitating a crisis in that area
    of science.

43
Scientific Revolution
  • When a crisis occurs, a new paradigm is sought
    out to replace the existing paradigm.
  • Kuhn called the event where one paradigm was
    rejected and another found to replace it a
    scientific revolution.

44
Incremental Progress
  • Generally speaking, the old paradigm and the new
    paradigm are not compatible. Facts in one do not
    translate into facts in the other.
  • This runs contrary to the commonly held idea
    that, over time, science gradually increases its
    knowledge about the natural world.
  • Kuhn describes different paradigms as being
    incommensurable

45
Differences between Paradigms
  • According to Kuhn, no aspect of the paradigms are
    spared this incommensurability.
  • Paradigms do not share
  • Facts
  • Problems and solutions
  • Terms (even if they happen to have the same form,
    they do not share meaning)
  • Statements or subject matter

46
Kuhns Strong Position
  • Can Kuhn really mean what he is saying here?
  • Wouldnt measurements and basic observations
    (like Smoke rose into the air) still be
    consistent across paradigms?

47
Paradigm- A world filter
  • According to Kuhn, a paradigm is like a filter
    that affects every aspect of the way we perceive
    the world.
  • To gain a better understanding of what this
    means, consider the following analogy- the helmet
    analogy
  • All scientists wear special helmets, which
    transmit to them the sights, sounds, smells, of
    the real world. However, the helmet also acts as
    a filter and changes this sensory information
    when it is passed to the scientist.

48
Different Paradigms, Different Worlds
  • For scientists whose helmets have the same
    filter, the world will appear the same.
  • For scientists who do not share the same filter,
    even simple observations will be experienced
    differently.
  • A paradigm is like one of these filtering
    helmets. It completely determines our perspective
    of the world.
  • Kuhn believes we need the filter provided by the
    paradigm in to have any understanding of the
    world.

49
Kuhn the Relativist?
  • Kuhn does not think that different paradigms
    provide more or less accurate version of reality.
  • Returning to our analogy, it is not that some
    helmets have less of a filter than others.
  • Given this, does Kuhn think that any one paradigm
    is any better than any other paradigm?
  • This is similar to the question we discussed
    earlier about theories- how do you decide which
    theories are better than other theories?

50
Kuhn Tries to avoid Relativism
  • Kuhn most emphatically does not wish to be
    considered a relativist.
  • He develops a number of criteria on which to
    compare paradigms.
  • Briefly, they are (Hung p.384)
  • Problem solving ability
  • Quantitative Precision
  • Predictive power (ability to make unexpected
    predictions)
  • Consistency
  • Simplicity
  • Aesthetics
  • Future Promise

51
Evolutionary Science
  • Kuhn does thinks that the paradigms of science,
    over time, get closer and closer to meeting his
    criteria- automatically!
  • How does he think this happens?
  • Kuhn was a fan of Darwins theory of evolution
    and believed that, in some sense, it was
    applicable to the generation of paradigms in
    science.

52
Evolving Paradigms
  • Kuhn believed that paradigms are chosen through
    an evolutionary process.
  • Multiple paradigms compete with each other for
    selection by the scientific community.
  • The paradigm that is the fittest (based on the
    criteria proposed by Kuhn for evaluating
    paradigms) is selected as the current paradigm.
  • New paradigms are created by scientists and are
    enter in the paradigm competition.

53
Kuhn and Truth
  • What is Kuhns position on truth (and falsity)?
  • Kuhn doesnt think the idea of truth really makes
    much sense.
  • Remember that our earlier definition of a true
    statement was a statement which accurately
    corresponded with the way the world out there
    existed.
  • According to Kuhn, the statements we make and the
    facts we discover are determined by which
    paradigm we have.
  • Consequently the idea of truth doesnt make
    sense.

54
Differences between Kuhn and Classicists- I
  • Classic Science
  • Science depends for its success on critically
    assessing proposed hypothesis.
  • Science must determine, as rigorously as
    possible, the truth value of proposed hypothesis
  • Kuhn
  • Science is not about critical inquiry. Rather
    science is about maintaining the status quo
    (whatever it may be at the time)

55
Differences between Kuhn and Classicists- II
  • Classical Science
  • Testing is critical in science- in particular for
    determining the truth and falsity of theories
  • Kuhn
  • Science operating under a paradigm does involve
    testing, but the testing does not address the
    validity or truthfulness of the paradigm itself.
  • Testing only exists to test consequences or facts
    that are derived within the context of the
    paradigm.

56
Differences between Kuhn and Classicists- III
  • Classical Science
  • Science allows for the steady accumulation of
    knowledge about the natural world.
  • Kuhn
  • Science is cumulative while operating under a
    particular paradigm, but when this is overthrown
    and replaced by a new paradigm, science must
    begin collecting knowledge from scratch again.

57
Criticisms of Kuhn
  • There are two main directions taken in criticisms
    of Kuhn
  • The relativist direction
  • The objectivist direction

58
The Relativist Direction
  • Kuhn wished to deny that he was a relativist, but
    his theory of paradigms is perilously close to
    being relativistic.
  • The only aspect of Kuhns philosophy which saves
    him from this are his criteria for evaluation of
    paradigms.
  • However, even Kuhn acknowledges that these
    criteria are vague and difficult to explain
    precisely. He intends them only as guidelines,
    rather than as rules for good paradigm creation

59
Embracing Relativism
  • Consequently, philosophers often say that Kuhn
    cannot avoid being a relativist, despite his
    efforts.
  • Some philosophers, like Paul Feyerabend
    (1924-1994), embraced relativism in science (and
    in general).
  • These philosophers say Kuhns theory of science
    is relativist, but that is just fine!.
  • Other philosophers who believe that science is
    not relative say that this reveals the
    incorrectness of Kuhns ideas.

60
The objectivity direction
  • Other philosophers argue that Kuhn is wrong when
    he tries to suggest that science is subjective.
  • Their objections typically involve attempts to
    find problem with Kuhns conception of paradigms
    and how science functions using these paradigms.
  • For instance, Israel Scheffler (1923 - present)
    argues, among other things, that basic
    observations, at least, are consistent among
    scientists, regardless of their personal biases
    or the theories held by them.

61
Lakatos- An attempt to compromise
  • Kuhns philosophical ideas were too controversial
    to be adopted wholesale by the philosophical or
    scientific community.
  • However, they were taken seriously enough that a
    serious effort was made to incorporate aspects of
    Kuhns ideas into the traditional view of
    science.
  • In particular, Imre Lakatos (1922-1974) tried to
    develop a comprehensive philosophy of science
    that integrated Popper and Kuhn.
  • How could Lakatos hope to unify two such
    seemingly disparate theories?

62
Combining Popper and Kuhn
  • Recall that, for Popper, the most important
    aspect of science was its effort to falsify
    proposed hypotheses.
  • Even though this seemed like a promising and
    original idea, we discussed a number of serious
    problems with Poppers efforts to make
    falsification the core of scientific practice.
  • Lakatos tries to fix this by redefining the idea
    of falsification, using some ideas put forward by
    Kuhn (and Feyerabend).

63
Competing Theories
  • According to Lakatos, falsification of a theory
    only occurs relative to another theory.
  • Lakatos says that that a theory is false if it is
    compared with a competing theory and
  • The new theory has higher empirical content-
    which means that it predicts some facts that
    arent predicted by the original theory
  • The new theory manages to explain all of the
    observations that the old theory could explain-
    it encompasses the old theory
  • Some new aspect of the new theory have already
    been corroborated.

64
A strange characterization of False
  • If a new theory meets all of these criteria then
    the old theory is considered to be falsified,
    relative to the new theory.
  • The new theory can be said to be better than the
    old theory, and should be adopted by science.
  • We can see that this isnt the idea of falsified
    that we tend to use. Lakatos still called this
    falsification because of the parallels to role
    of falsification in Poppers theory.

65
An Objective Kuhn? A Subjective Popper?
  • When considering Lakatos we can see how he tried
    to reach a compromise between Popper and Kuhn by
  • Changing some of Poppers ideas to make them more
    subjective (like his idea of falsification)
  • Changing some of Kuhns ideas to make them more
    objective (like his idea of paradigm shifts)

66
Present Day Philosophy of Science
  • We have arrived at present day philosophy of
    science!
  • Philosophers of Science continue to scrutinize
    science
  • With new scientific activities they ask- is this
    really science? Is it following the accepted
    methods of science?
  • With science in general they debate issues like-
    how objective/subjective is science? Is
    objectivity/subjectivity good or bad in science?
    What role should science play in our society?

67
Next Week- Final Test
  • Included some review questions in last weeks
    slides
  • This week talked about
  • Classical Science (and philosophy of science)
  • The realism/anti-realism debate
  • Kuhns theory of science

68
Some questions to get you thinking about
  • The Classical Tradition
  • What was the classical tradition? What
    characterized the classical tradition? When did
    it start and stop? What assumptions did classical
    science make? What caused the classical tradition
    to be cast aside by some scientists and
    philosophers? How does philosopher xs theory
    compare with the assumptions of the classical
    tradition (e.g. Comte, Popper, Duhem, Quine,
    Kuhn, etc. etc.)

69
Some questions to get you thinking about
  • The realism anti-realism debate
  • What was the realism/anti-realism debate? Which
    philosophers are anti-realists? Why are they
    called anti-realists? How many types of
    anti-realism did we discuss? What is the
    difference between soft and hard anti-realism?
    What is the difference between Duhems and
    Comtes thoughts/arguments regarding theoretical
    entities? Did Quine agree with Duhem? If yes, in
    what way? If no in what way? State Duhems
    argument. State Quines argument. Are you
    convinced by Duhems argument? If yes, are you
    convinced by Quines argument? If no, how can you
    save Duhems argument from Quine?

70
Some questions to get you thinking about
  • Subjectivity/Kuhn
  • Define subjectivity. Define Objectivity. What is
    the difference between saying that the world is
    subjective and saying that a person is
    subjective? Why did scientists in the classical
    tradition think that subjectivity was so
    problematic for science? What did Kuhn think
    about subjectivity and science? If Kuhn said
    subjectivity was okay and the classicists said it
    wasnt- what led them to such different
    conclusions about subjectivity? How does Kuhn
    describe the progression of science? According to
    Kuhn, how does a person become a scientist.
    Describe the historical progression of science,
    according to Kuhn. Cont

71
Some questions to get you thinking about
  • Kuhn, cont
  • What stages does science pass through, according
    to Kuhn? What is the connection between Kuhn and
    evolution? What are some criticisms of Kuhn? How
    did Lakatos attempt to unite the classic
    tradition and Kuhns theory?
  • General
  • Can you create a timeline of all philosophers
    discussed after the midterm? Can you say what
    their major theory was, what motivated them to
    create their theory and two problems with their
    theory?
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