Transcript Lecture 3 - Philosophy HKU

Philosophy of the Sciences,
Lecture 3, 13/09/03
The Demarcation Problem and
Falsificationism
Science is an invention, a relatively recent
invention.
There was a time in our history when there
was nothing to which we’d happily apply our
word ‘science’.
Not until the 17th century did what we would
recognize as modern physics emerge (via
Newton and his discoveries) as a separate
discipline.
What we think of as biology didn’t exist until
1859 (when it emerged with the publication of
Darwin’s Origin of the Species).
Psychology as we know it had to wait until the
beginning of the 20th century, and computer
science is an infant—only a little more than 50
years old!
Physics and biology are descendants of the
philosophical sub-discipline known as
metaphysics—roughly, the study of what there
is: what fundamental kinds and properties there
are and how they relate.
And psychology descends from philosophical
reflection on the nature of the mind and its
properties, i.e. the philosophy of mind.
Computer science, for its part, stems from
philosophy’s millennium long interest in logic.
Interestingly, all of these sciences grew from
philosophical roots. (From the concerns of the
ancient Greek philosophers and primarily from
the concerns of Aristotle).
What makes a theory scientific?
The question is:
•intrinsically interesting
•of practical importance
-Who gets the money?
-Who wins the argument?
•crucial for understanding the value of science
-Science is an invention, claimed by
many to be humanity’s best.
A better formulation:
What distinguishes science from non-science?
(the demarcation problem)
Initial proposals:
(1) Science offers explanations.
(2) Science is objective.
(3) Science is descriptive.
(4) Science makes predictions.
(5) Science proceeds from observation.
The trouble with the initial proposals:
They don’t do any distinguishing.
Popper
The wrong answer to the demarcation
problem:
Science is inductive; it proceeds by
observation and experiment.
Why the wrong answer?
Non-scientific theories can be based on
observation and experiment.
“…astrology with its stupendous mass of
empirical evidence based on observation—on
horoscopes and biographies.”
Popper’s 4 candidate theories:
(1) Einstein’s theory of relativity.
(2) Marx’s theory of history
(3) Freud’s psychoanalysis
(4) Adler’s individual psychology
Popper’s intuition: (1) is scientific, (2)-(4) not.
Truth not the issue. At the time, Popper didn’t
believe that Einstein’s theory was true.
Exactness also not the issue.
The appeal of (2)-(4): Their apparent
explanatory power.
Exposure brought about an “intellectual
conversion” and confirming instances of the
theory were seen everywhere.
Indeed, nothing seemed to count as
disconfirmation, as evidence against the
theory.
Every observation could be interpreted in light
of the theory.
The Freud vs. Adler example. (p. 40)
The difference with respect to (1)— Einstein’s
theory: The theory makes risky predictions,
predictions which, if false, sink the theory.
E’s theory has the result that light, like material
bodies, is attracted by heavy bodies such as
the sun. This led to the prediction that the light
from certain stars—those which appear in the
night sky as close to the sun—would appear, if
observed in daylight, as slightly shifted away
from their normal position, slightly further away
from the sun.
This prediction can’t be tested in ordinary
circumstances because of the sun’s
brightness.
But during an eclipse one can take a
photograph of a star’s apparent position in the
daytime sky.
And then photos of the star taken in the day
and in the night can be compared and its
apparent distance from the sun can be
measured.
This is just what Eddington did.
And the prediction of Einstein’s theory was
shown to be correct.
The significance of this, acc. to Popper:
Einstein’s theory, unlike (3)-(4), is
incompatible with certain possible results of
observation.
In other words, E’s theory is refutable or
falsifiable (the term that has stuck). It is
possibly false. If our observations had been
different, it would have been shown to be false
(though they weren’t and it wasn’t).
This, then, is Popper’s solution to the
demarcation problem: A theory is scientific just
in case it is falsifiable.
A theory is scientific just in case it is falsifiable.
Remember: Truth is not the issue for Popper.
Accordingly, his solution to the demarcation
problem doesn’t make being true a criterion
for being science.
Theories that are true may be falsifiable.
But, equally, theories that are false may be
falsifiable as well.
Some consequences and corollaries of
Popper’s solution to the demarcation problem:
•Theories not falsifiable by any conceivable
event are not scientific. (Thus, the naïve view
that science strives for irrefutability gets things
exactly the wrong way around.)
•Every good scientific theory is a prohibition--it
denies that certain things may happen.
•A test of a theory is an attempt to falsify it.
•“Confirming evidence” is too easy to come by
and should only count towards the
acceptability of a theory if it is the result of an
attempt at falsification.
•Some genuinely falsifiable theories, when
falsified, are maintained by their admirers
either by re-casting the theory or adding
auxilliary assumptions. Such a procedure is
always possible, but it rescues the theory only
by destroying or reducing the theory’s claim to
scientific status. (Popper calls such rescue
operations conventionalist twists.)
Who passes the falsification test?
(1)—Einstein’s theory of relativity—passes.
makes risky predictions (re: the apparent
positions of stars, e.g.)
It
Astrology fails. Vagueness of its predictions
makes it unfalsifiable.
(2)—the Marxist theory of history—fails. It once
passed, but it was given various
conventionalist twists.
(3) and (4)—the psychoanalytic theories—fail.
No conceivable bit of human behavior could
refute them.
Non-science but not unimportant. Analogy
with primitive myths. These myths often
shape later science (the ancient Greek
examples).