Download Worldviews, by Richard Dewitt

Worldviews, by Richard Dewitt
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Chapter 8: Instrumentalism and Realism
We usually speak of the advancement of knowledge and
understanding as the fundamental goals of science, but
just as the bottom line in business is increasing profit, the
bottom line in science is increasing predictive success.
When a scientific theory repeatedly makes impressively
precise and accurate predictions, especially with respect
to previously unpredictable phenomena, it gets noticed.
And at that point it seems reasonable to ask why it is so
successful in this regard, where other theories have
failed.
More precisely, if T1 and T2 are alternative theories
regarding the same range of phenomena, and T1 makes
consistently better predictions about these phenomena
than T2, then it seems like there has to be a reason for
this, and the most obvious and plausible reason is that T1
is a truer, more accurate representation of reality than T2.
Philosophers who think this way are called realists.
Realists believe that the most fundamental aim of a
scientific theory is to provide an accurate model of reality,
and moreover that the best explanation of the fact that a
theory achieves this kind of accuracy is that the theory is
true.
So those who subscribe to a realist interpretation of the
theory of the atom, for example, believe that there really
are, atoms which themselves really are made of various
types of charged subatomic particles.
(Similarly, people who subscribe to a realist interpretation
of mathematics believe that numbers are just as real as
atoms. And people who subscribe to a realist
interpretation of morality believe that moral properties like
good and evil are just as real as numbers and atoms.)
So why wouldn’t someone be a realist about atoms? The
answer lies in the empiricist tradition of science. For
centuries scientists agreed that scientific knowledge
concerned only that which was, in principle at least,
observable. This was a good thing in that it meant that
spooks could not be invoked to explain eclipses, comets,
bad weather, disease, etc. (Of course most scientists of
the 16th-19th centuries believed in spooks, they just didn’t
allow them into scientific explanations.)
The problem with this very hard line empiricism is that it
makes it impossible to acknowledge the existence of very
small things, and very far away things, since very small
and far away things can’t be observed with the naked
eye. Telescopes and microscopes eventually softened
this attitude to some degree, but scientists eventually
found themselves explaining the results of various
experiments by positing the existence of entities that
were in principle unobservable. No one has ever seen,
or ever will see an atom. Rather, scientists posit their
existence to explain a range of phenomena that can be
observed.
An instrumentalist, then, is someone who typically
adheres to a hard line empiricism, granting reality only to
things the can actually be observed. The instrumentalist
accepts scientific theories involving unobservable entities
as useful predictive instruments, but she remains
agnostic with respect to the question why they are useful
predictive instruments.
Philosophers of science will usually identify themselves
as being realists or instrumentalists with respect to
scientific theories generally. However, within science
most theories are at least candidates for realistic
interpretation.
Your author points out that within science itself theory
acceptance goes through an instrumental stage before
being considered a candidate for realistic interpretation.
The Ptolemaic system.
The ancient astronomer Ptolemy (150 A.D.) defended the
geocentric conception of the universe against the
apparent violation of Plato’s dictum. Years of careful
observations had demonstrated unequivocally that the
planets did not appear to be moving in uniform circular
orbits, which is what Plato’s dictum required. Rather,
they would occasionally and regularly start moving
backwards.
(It’s interesting to ask for the basis of this dictum, and the
answer seems to be mainly aesthetic. Circular motion
represented a standard of perfection and beauty.)
Ptolemy solved that problem by posing a model that
preserved the circular motion, by creating epicyles.
Retrograde Motion