Science news

1
Science news

• Becoming Human, 3 part series by NOVA, began
  last Tuesday night and continues for 2 more weeks
  on Tuesdays.
• One hypothesis considered as an explanation of
  evolution of human mental capacities/brain size
  climate change.
• Earlier hypothesis emphasized bidpedalism, but
  that was before we found fossils of other
  hominids with relatively small brains.
• Prediction? NY Times review If we go through
  another period of increasingly hot and dry
  climate, our descendants might be much smarter
  and have heads the size of basketballs ?

2
Science news

• Signs of early Homo sapiens in China?
• Fossils over 100,000 years old found in southern
  China
• Taken by Chinese scientists to challenge the
  hypothesis that the species originated in Africa
  and spread from there
• Critics Far too little evidence
• A fragment of a lower jaw bone and some teeth

3
Challenges to Falsificationism

• Complicating the logic of falsification
• If H, then I is really If H (A1 An),
  then I
• More from Hempel
• I in If H, then I
• is itself shorthand for If C, then E
• where C symbolizes some condition, and
  E some event or phenomenon.
• And if C, then E
• is understood as if some condition is brought
  about, then we will observe E .
• If this is correct, then the actual logic of
  falsification, on Hempels model, is

4
Challenges to Falsificationism

• If H (A1 An), then (if C then E)
• Not E
• ----------------------------------------------
• Either not H (A1 An) or not C
• On the left side, H may be incorrect but it
  could be correct and one or more of the auxiliary
  assumptions is the problem (Brahe).
• Or (as indicated by the right side), it may be
  that the conditions werent brought about (med
  students didnt wash their hands...)

5
Holism as yet another challenge to
Falsificationism

• Duhem/Quine thesis It is bodies of theory (or
  systems of theories), not individual hypotheses,
  that entail predictions.
• If T (for some body of theory), then (if H, then
  I)
• Not I
• ---------------------------------------------
• Not some one or more statements of T or not H
• Pierre Duhem a bench physicist writing in the
  1930s
• W.V. Quine philosopher of science writing from
  the mid twentieth century to its end

6
Holism

• If T, then (if H, then I)
• not I
• ------------------------------
• Not some part of T or not H
• Given what actually follows logically and
  empirically from not I, one needs to decide
  that not H follows, rather than some part or
  whole of T i.e., one has to choose to hold T
  firm and H infirm.
• Are the choices arbitrary? Made on the basis of
  self-interest?
• What are the consequences for objectivity?

7
Holism

• Duhems examples (you do not need to memorize the
  details just what he uses them to illustrate)
• Neumann assumed a hypothesis that, if correct,
  was taken to predict that in an experiment
  involving a light beam reflected at a particular
  degree of angle, there ought to appear
  alternatively dark and light interference bands
• Weiner, who challenged Neumanns hypothesis,
  performed a test in which the predicted
  interference bands did not appear.
• Had he, in fact, falsified, Neumanns hypothesis?

8
Holism

• Duhems examples
• No, according to Duhem, because Weiner had not
  only used Neumanns hypothesis to get the
  prediction and design the experiment instead he
  brought and joined a lot of hypotheses to do
  both.
• So what he actually demonstrated was that either
  Neumanns hypothesis is incorrect, or one or more
  of the assumptions Weiner himself made, was/were
  incorrect.

9
Holism

• In the case concerning whether light would travel
  faster in water than in air or vice versa as a
  test of Newtons hypothesis that light consists
  of tiny projectiles vs. that light consists of
  waves moving through a medium
• It was the whole system Newton proposed that was
  under test, not the hypothesis that light is made
  up of projectiles
• So, the moral is the same
• Nothing, logically or experimentally, stops us
  from accepting the hypothesis allegedly falsified
  and shifting the weight of the experimental
  contradiction to some other hypothesis or part of
  the larger theory that the experimenter assumes.
• Both experiments Duhem cites had been taken as
  among the most decisive ones in optics he is
  challenging this.

10
Holism

• The model of Falsificationism as how scientists
  do or should reason, reflects unfamiliarity with
  physics actual functioning
• Such people assume that each one of the
  hypotheses employed in physics can be taken in
  isolation, checked by experiment, and then when
  many varied tests have established its validity,
  given a definitive place in the system of
  physics.
• In reality, this is not the case. Physics is not
  a machine which lets itself be taken apart
  physical science is a system that must be taken
  as a whole If something goes wrong, if some
  discomfort is felt it, the physicist will have to
  ferret out which organ needs to be remedied
  or modified without the possibility of isolating
  this organ and examining it apart.

11
Holism

• So-called crucial experiments
• Assume the logic of Reductio ad absurdum, an
  argument form that works in mathematics
• But not, Duhem argues, in empirical science
• Either P or Q 1. Either H1 or H2
• Not P 2. Not H2
• ----------------- -------------------
• Q H1
• Recall Paleys reasoning

12
Holism

• Reductio ad absurdum only works if one can list
  all the hypotheses that can account for some
  phenomena and then by experimental contradiction,
  eliminate all except one.
• If you could do this, the resulting hypothesis
  would look like a certainty.
• But you cannot. One can never be sure one has
  identified every possible hypothesis that might
  account for the phenomena.

13
Holism

• An example In the late 1980s, researchers
  developed a drug predicted to be capable of
  thwarting the replication of the HIV virus
  implicated in AIDS.
• H All things being equal the drug will be
  effective
• In experiments, one group was given the drug and
  the other a placebo.
• The initial trials (running over 2 years)
  confirmed the drugs predicted success. But in
  the 3rd year, it stopped being effective.
• Initial results (showing effectiveness) were
  taken to be mistaken
• And the hypothesis was rejected by some

14
Holism

• Then current theories suggested that it didnt
  matter if the drug was stored and delivered in
  glass or plastic containers.
• After the initial 2 year period, the drug was
  stored and delivered in plastic rather than glass
  containers.
• Thus the conclusion that not H presumed the truth
  of this background knowledge and it was wrong.
• Storing the drug in plastic containers did affect
  it.

15
Holism

• Critics of the Quine/Duhem (or Duhem/Quine)
  thesis argued that if correct, theories could
  never be refuted by evidence but only by
  decisions made by scientists in the relevant
  field
• This, they argued, leads to relativism and/or
  degrees of subjectivity that challenge scientific
  objectivity
• Duhem and Quine not so. It just means that
  science isnt a machine.
• Duhem the physicist is more like a doctor making
  a diagnosis with available information, than a
  watchmaker who fixes a watch.

16
Holism

• Later in the full chapter, Duhem argues that
  there are values (epistemic or cognitive) that
  guide the scientists choice
• A list many cite includes
• Simplicity
• Conservatism
• Explanatory power
• Empirical adequacy and/or success
• Fruitfulness

17
Part 2

• Introducing Kuhn

18
Kuhns The Structure of Scientific Revolutions
(SSR)

• First published in 1962, Kuhns SSR was named one
  of the 50th most important books of the 21st
  century by many lists (including The New York
  Times)
• Kuhn a bench physicist who became interested in
  the history of science (actual history) and
  argued that it did not match the reconstructions
  philosophers and historians of science, and
  scientists themselves, offered
• While historians and philosophers of science (as
  well as scientists) emphasized revolutions in
  science as models of how science works, Kuhn
  emphasized what he called Normal Science the
  kind of science most scientists engage in all of
  their lives that does not look what philosophers
  or historians of science, or even working
  scientists, hold up as scientific method

19
Kuhns SSR

• From pre-science to normal science to
  crisis to revolution
• Pre-science Lots of schools arguing over
  fundamentals
• No agreement over what is the most important
  phenomena to be explained
• No agreement on a basic theory or how the most
  basic phenomena are to be explained
• The emergence of a paradigm
• The beginning of a normal science (as opposed
  to a pre- science) tradition
• The emergence of a paradigm which
• Solves a lot of puzzles (or promises to solve
• puzzles) that need to be solved
• Is open-ended enough to leave lots of work to
  do

20
Kuhns SSR

• Is like a judicial decision in that it invites
  further articulation
• Brown v. Board of Education
• Separate but equal is internally inconsistent
• Originally about racially-segregated schools
• But articulated to apply to other apparently
  separate but equal laws and practices
• Gender
• Sexuality
• And other laws that cite separate but equal
  standards

21
Kuhns SSR

• Once a science community accepts a paradigm
  (Copernican astronomy, Newtonian physics,
  Darwinian natural selection, Relativity, Quantum
  physics) the paradigm itself is unquestioned and
  work begins on
• Puzzle solving the paradigm indicates what
  problems are important (nature of the orbits of
  the planets, how natural selection works.) and
  this results in a
• Puzzle-solving tradition

22
Kuhns SSR

• Normal science (everyday, most of the time
  science) involves puzzle solving
• Assume that any puzzle suggested by a paradigm is
  intrinsically important and
• Has a solution that the paradigm, itself,
  supplies
• Can be solved with sufficient ingenuity and/or
  creativity
• Any failure to solve the puzzle is due to the
  researcher (her or his understanding of the
  puzzle, appropriate tests but not the paradigm.

23
Kuhns SSR

• Normal science (everyday, most of the time,
  science) is a closed-minded enterprise
• Is not looking for anomalies
• Seeks only confirming evidence of the Paradigm
  and any subsidiary hypotheses it suggests
• Is an attempt to fit nature into the boxes the
  Paradigm supplies
• Will only pay attention to anomalies
  (counter-examples) when
• It is no longer reasonable to blame the
  individual researcher/test or
• To wait for scientists of the next generation to
  find a solution or
• there is a competing paradigm

24
Kuhns SSR

• Kuhns diagnosis of how Popper went wrong
• Not because (as Duhem article would suggest) that
  Popper didnt know the history of science
• But because he focused his attention on episodes
  of revolution
• These, according to Kuhn, are rare and not
  typical of how science proceeds