Philosophy of Science, Spring 2008, T/H 9:25-10:40 (TH 277)
Instructor: Bryson Brown, B864 (x2506, brown@uleth.ca)
Office hours: T/H, 11:00-12:00 and by appt.
1. Text: Godfrey-Smith, Theory and Reality. (Chicago: The University of Chicago Press, 2003).
2. Introductory remarks: The nature and proper understanding of science are controversial for
many. The significance of these issues, however, is unavoidable: science plays a very important
role in our culture, both rhetorically (the phrase ‘scientific creationism’ was invented by
creationists bent on laying claim to the special authority and prestige associated with the word
‘science’), and substantively (scientific ideas and institutions play central roles in many areas of
endeavour). There are many different positions that scholars have taken in response to the
special authority that science seems to possess. For some, this authority is like any other form
of political authority, grounded in social hierarchy and perpetuated by propaganda, training and
the self-serving pursuit of the interests of scientists and those they work for. For others, science
is a paradigmatic example of a very different kind of authority—authority grounded not in mere
social standing, power or rhetoric but in an established record of meeting the standards
appropriate to the kind of authority science has.
The special authority of science is, first, epistemic: when we look for certain kinds of
information, we turn to science for the answers. Examples in many different fields come to
mind: If we want to know what atoms are made of, we look to physics. If we want to know
about battery technology, it’s electro-chemistry. If we want to know about the cause of a
particular infectious disease, micro-biology is the key. If we want to know about our relations to
other forms of life, evolutionary biology and biochemistry are the key sources. But why do
these answers have authority for us? Why do we tend to accept the existence of atoms as
established fact, after so many centuries in which atoms were the subject of philosophical
debate and justified scepticism? How can we know the existence of protons, neutrons,
electrons and all the rest of the menagerie of sub-atomic particles when none of them is large
enough to see or feel directly? Why do we accept the ‘germ theory’ of disease, when two
hundred years ago it was far from settled? Why do palaeontologists and evolutionary biologists
hold that we unquestionably share a recent common ancestor with the chimpanzee, a claim
many still find outrageous and unacceptable? If the authority of science is as unfounded, as
contestable, as the authority of particular religions or political parties, then these claims are only
‘justified’ from a point of view that endorses a particular claim to authority—their justification
is, in a sense, subjective: they not justified for all of us but only for those who accept the special
authority of science (just as some accept the special authority of the Pope on certain questions).
However, this degree of relativism is very hard to defend—only an extreme scepticism can carry
the load. Much of what science has to say about the world is grounded in familiar,
straightforward observations and reliable patterns of events that we are able to observe (and
often to produce) over and over again.
One central question in philosophy of science is how we come to have evidence for the claims
that science makes—this is particularly difficult for empiricists who believe that at least some of
the generalizations scientists have come to accept are justified by the particular observations we
have made: Do observations of the orbits of planets, falling bodies and the tides really provide
evidence for Newton’s law of gravity? Do observations of the tree-structure of resemblance and
differences between living things really provide evidence for descent with modification
(Darwin’s phrase for evolution)? Induction and explanation both come into the discussion
here—and efforts by the logical empiricists to give a formal account of induction are generally
accepted to have failed badly.
Sir Karl Popper proposed a radical solution to this challenge—to accept Hume’s scepticism and
insist that the key to scientific method is not the confirmation of claims, but their falsification.
This position, initially grounded in an obvious logical point, failed badly: Falsification requires
that we accept some observation sentences as true (something we can always be wrong about,
unless the observations are very weak) and have sufficient other premises also accepted as true
for the observation to refute the theory. Worse, Popper’s account can’t provide any good
advice on what theories we should actually use when it comes to (say) designing and building a
bridge. Without this kind of practical induction, an account of science is detached from a
central aspect of our use of science—an aspect, furthermore, about which we are extremely
confident.
Science is often invoked in the course of explanation—in fact, for some, the contribution that
science makes to explaining things is the key to understanding its special epistemic authority.
And explanation does seem to play a central role in how we justify both retail beliefs and
theories. However, the nature of this role and what it contributes to the justification of various
kinds of belief remains highly controversial.
Metaphysical issues arise when we accept that science has real epistemic authority—does this
mean that there ‘really are’ electrons and quarks? Or is the epistemic authority of science
limited to telling us about what is (in some sense) observable, rather than about the entities we
use to explain what we observe? Are scientific theories really just a ‘means to an end’, an end
specified in terms of some privileged language that all our descriptive commitments must be
couched in? Or do they offer real and better descriptions of the world, couched in a new kind of
language?
If science doesn’t provide us with certainty, perhaps we should interpret it (and our attitudes
towards it) in terms of probability instead. Some recent philosophers are impressed by Bayes’
rule, a theorem of probability theory that relates the conditional probability of a hypothesis H
on some evidence E to H’s initial probability, the probability of E and the conditional probability
of E on H: P(H/E) = P(H) * P(E/H)/P(E). This theorem captures the intuitions that a hypothesis
that makes a testable prediction is confirmed when the prediction turns out to be true, and
confirmed more strongly if the prediction is unlikely. But it also shifts our attention to a
different question, which Bayesians often avoid: where do we get the probabilities that Baye’s
rule depends on? Once we have these ‘input’ probabilities, Bayes’ rule is trivial; without them,
it’s pointless. Still, many philosophers have endorsed the idea that all rational change of belief
(in response to new information) must take the form of applying Bayes’ rule (perhaps in slightly
more general form) to go from initial probabilities to a new probability assignment, assigning to
each sentence its conditional probability given our new information.
Readings: We’ll be using Theory and Reality, by Peter Godfrey Smith, as our main text; after the
first week, I’ll be adding a supplementary paper (possibly two) to the readings, to give you a
more direct feel for the literature and how some of the figures mentioned in the text wrote
about their ideas. The paper for Week 2 is a critique of some older approaches to the history of
science, and especially the ‘scientific revolution’.
Course Schedule:
Week 1: Thursday, January 3. Introduction: The roots of modern science
Week 2: January 8, 10. The scientific revolution. Chapter 1; supplementary reading: “DeCentring the 'Big Picture': "The Origins of Modern Science" and the Modern Origins of Science”
Andrew Cunningham, Perry Williams, The British Journal for the History of Science, Vol. 26,
No. 4, The Big Picture (Dec., 1993), pp. 407-432. (Available through JSTOR.)
Week 3: January 15, 17. Logical Empiricism, Induction and Confirmation Chapters 2,3;
supplementary reading, “Studies in the Logic of Confirmation (I.)” Carl G. Hempel, Mind, New
Series, Vol. 54, No. 213 (Jan., 1945), pp. 1-26. (Available through JSTOR.)
Week 4: January 22, 24. Popper and Falsificationism. Chapter 4; supplementary reading:
Nicholas Maxwell, “A Critique of Popper’s Views on Scientific Method,” Philosophy of Science,
Vol. 39, No. 2 (June 1972) pp. 131-152. (Available through JSTOR.)
Week 5: January 29, 31. Kuhn: Normal Science. Chapter 5.
Week 6: February 5, 7. Kuhn: Revolutionary Science. Chapter 6. Sample questions for the first
test distributed February 5.
Week 8: February 12, 14. Lakatos, Laudan, Feyerabend. Chapter 7.
First test, February 14.
Week 9: February 19, 21. No classes—Reading Week.
Week 10: February 26, 28. Sociology of science, feminism and science studies. Chapters 8, 9.
Week 11: March 4, 6. Naturalistic Philosophy. Chapter 10.
Week 12: March 11, 13. Naturalism and science as a social phenomenon. Chapter 11.
Week 13: March 18, 20. Scientific realism. Chapter 12.
Week 14: March 25, 27. Explanation. Chapter 13.
Week 15: April 1, 3. Bayesianism and evidence. Chapter 14.
Week 16: April 8, 10. Empiricism, naturalism, realism? Chapter 15.
Grades will be based on a test (February 14) (worth 25%) an essay (2500 words) due April 10
(40%), and a final exam, Wednesday April 23, 2:00-4:00 p.m. (35%). Drafts of the essay will be
accepted for red-inking up to April 3.