Download document

UW and the Hubble


The captain of the space
shuttle, Atlantis, which
took off yesterday to fix
the Hubble is a UW
graduate in engineering.
The mission includes a
new camera that UW
faculty in aeronautics and
astronautics helped
develop.
Hubble’s 19th anniversary
April 21 this year
Released one of most
interesting pictures
A peculiar set of galaxies
called Arp 194: several
galaxies and a cosmic
fountain (of stars, gas,
and dust) that stretches
over 100,000 light years
The blue: star forming
regions
Scientific Explanation
Evolution and medicine
 HIV virus: RNA-based retrovirus
 Replicates at a fast rate
 Low copying fecundity
 So lots of mutations
If all of the various “cocktails” stop working for a
patient with HIV, frequently he or she and their
doctor will gamble:
Take the patient off all medications so that the
“wild type” re-emerges and blast it with meds
that once worked.
Scientific Explanation

Why sex?
 It
is expensive in lots of ways…
 But it allows for diversity of one’s offspring which
might protect them in terms of new challenges (new
pathogens, other environmental changes, etc.)
 The guppies in pools
The Red Queen hypothesis…
 Not an explanation of how sex initially evolved
(still an ongoing research question)

 Natural
dumb)
selection can’t “look forward” (it’s blind and
Scientific Explanation

Sexual selection (Darwin)
 Male/male
competition for females
 Female choice of mates
 To take care of apparent counter-examples to natural
selection

Parental Investment Theory (1960s)
 Gametic
dimorphism (sperm are small, numerous, and
“cheap”; eggs are large, relatively few, and “expensive”)
as are other aspects of reproduction that often fall on
females (egg sitting, gestation, lactation, caring for
young in general…)
 So parental investment differs by sex…
Scientific Explanation

Parental Investment Theory (1960s)
 Gametic dimorphism
 This
difference is supposed to explain the 2
processes that make up sexual selection.
 Is also supposed to explain sex differences in
temperament, behavior, and mating strategies
 “It pays males to be promiscuous and it pays females
to be choosey”
 So it is also supposed to explain “The battle between
the sexes”
 And so-called double standards in numerous cultures
Scientific Explanation




Parental Investment Theory (PIT, 1960s)
Challenges and current status
From within evolutionary biology:
 If sexual selection is a force at all, its role is very minor (Ernst
Mayr)
 Many cases previously explained using PIT or SS turn out to
be explicable using natural selection
 Sperm are not cheap to produce (Richard Dawkins)
 Gender stereotypes shape the theory and the observations
made by those who assume it
 Females were supposed to be monogamous… but songbirds
in film…
 Ordinary chimpanzees vs. Bonobos
 In fact, most species spend less time courting and mating
than many other activities
Evolutionary psychologists still maintain it.
van Fraassen’s account



Explanation is not a formal relationship (defined in
terms of logic) between a law-like statement and
some phenomenon
Many scientists and philosophers now see
“understanding’ rather than explanation and
prediction as the primary goal of science
Explanation in science is a pragmatic relationship –
context and practice dependent:
 “Why” questions are asked, and regarded as
answered, within specific scientific contexts
 To understand them (and what will count as an
answer) requires knowledge of the scientific
context within which they are asked.
van Fraassen’s account

Reminders:




Answers to a question such as “why sex?” will
greatly vary depending on context (religious vs.
scientific, and within different scientific epochs)
So, too, the question “how did humans come
into existence?”
And “how are humans like other animals and
how (if at all) are they unique?”
And “why is nature uniform?”
van Fraassen’s account

“The Evolutionary Arms Game”





Struggle for existence
Why diversity, enabled by sex, matters in terms
of potential dangers and survival
Evolution at work:
Antibiotic resistant viruses (TB, HIV, …)
Early exposure and immunity
Review
Review
You should know
What Hume’s “problem of induction” is
What the remaining problem of induction is
and how it applies to science
What narrow inductivism is
What Hempel’s new account of inductivism
is
What the distinction is between discovery
and justification in the philosophy of science
Review
You should know
What the logic of confirmation is
What Falsificationism is
What the logic of falsification is
Challenges to both Hempel’s logic of confirmation
and Popper’s logic of falsification
What holism is and what Duhem’s argument for it
is
What the logic of “reductio ad absurdum” involves
And why Duhem says it cannot be properly used in
science
Review
You should know
What “normal science” is according to Kuhn
and how it is different from “pre-science” or
“pre-normal science”
The relationship between a paradigm and a
normal science research program
What Kuhn means by “puzzle solving” and
how he uses it to describe the activities in
normal science
The significant differences between
Popper’s account of scientific practice and
Kuhn’s
Review
You should know
What an “ad hoc hypothesis” is
What an auxiliary assumption is
Cases in which the latter were clearly at
work in apparent “falsifications”
Cases in which an added hypothesis (to take
care of a problem) was confirmed (thus, not
ad hoc)
Difficulties in determining, except in
hindsight, when a hypothesis is ad hoc
Review
You should know
What Hempel’s D-N model of explanation is
What problems it faces
What van Fraassen’s “pragmatic” account of
explanation is and how it challenges
Hempel’s model
How questions like “Why Sex?” and those
addressed in “The Evolutionary Arms Race”
fit better with van Fraassen’s account