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?