Chad Clark's Open Journal : 2007-12-06

1) Book review: The Structure of Scientific Revolutions by Thomas Kuhn

This book was first published in 1962.  I read the third edition (1996).

This is the book that led to the over-used term "paradigm shift".  Ignoring
misused buzz-words from managers in the past this book was a pleasure to read.

Kuhn breaks the progress of science into two states.  "Normal science" is the
normal state of events.  "Scientific revolutions" occur in between periods of
normal science.  (There is also discussion about a pre-science stage before
any accepted theory takes hold.)

In normal science the world has a well accepted theory (called a paradigm) of
how things work.  During normal science knowledge is advanced in small steps.
Things the precision of known constants are improved, more advanced machines
are invented and improved on.

Eventually the paradigm breaks.  This happens because some measured data does
not fit the theory.  The theory might be incomplete or completely incompatible
with observed behaviour.  This brings things into a state of crisis.

In the crisis state many potential new theories compete.  There are attempts
to modify the theory that just failed.  (Eg adding epicycles to a geocentric
model of the universe.)  After a while a new theory becomes generally accepted
by most.  This is the paradigm shift.  Encouraged by a new working model the
process of normal science resumes.

There are many more details in the book and there are many interesting things
about scientific revolutions.

Paradigm shifts happen over time.  It takes time for people who have invested
much in the old theory to switch to the new theory and many never do.  (One
that comes to my mind is Einstein rejecting strange quantum behaviour that is
generally accepted and relied on such as "quantum tunneling".)

Often the person credited with the new theory is new to the field and/or young
compared to many people in the field.  It can require someone not particularly
tied up in the old system to see a second way things could be explained.

The book gets a bit philosophical when explaining why it is difficult for two
people who believe different paradigms to explain their paradigms to each
other let alone convince the other to accept one's own paradigm.

I used the word crisis but revolutions have a scope of affected science.
Changes to ideas about how stars form need not affect experiments in heredity.
If they do, it might be indirect and take a while so there will not be crisis
in the latter field right away.

The book also mentions that people generally do not think of science as having
revolutions.  The common view is that science is a series of steps where each
step progresses knowledge and each step follows from the previous.

Kuhn claims that this view comes in part from our textbooks.  The history
portion of a science textbook provides context and explanation of the current
paradigm of the day.  The current paradigm is what drives normal science and
the textbook is how new people learn to practice normal science under the
current paradigm.

People who learn science from textbooks that leave out the crises do not learn
the detailed history so they think of history as being a series of progressive
steps.

I recommend this book to anyone interested in history of science.  Maybe also
to someone interested in how ideas spread through a group of people.