Manuscripts: Letter to Kuhn by Carnap

A letter (April 28, 1961) to Thomas Kuhn from Rudolf Carnap about the completion of his manuscript for the Encyclopedia of Unified Science:

Dear Professor Kuhn:
     Simultaneously I am returning your manuscript "The Structure of
Scientific Revolution". I am happy that it is now in final form and
that the U. of Chicago Press has found a way of publishing it in its
full length. I am especially gratified by the fact that we can incorporate
this work into the Encyclopedia.
     I am convinced that your ideas will be very stimulating for all those
who are interested in the nature of scientific theories and especially
the causes and forms of their changes. I found very illuminating the
parallel you draw with Darwinian evolution: just as Darwin gave up
the earlier idea that the evolution was directed towards a predetermined
goal, men as the perfect organism, and saw it as a process of
improvement by natural selection, you emphasize that the development
of theories is not directed toward the perfect true theory, but is
a process of improvement of an instrument. In my own work on inductive
logic in recent years I have come to a similar idea: that my
work and that of a few friends in the step for step solution of problems
should not be regarded as leading to "the ideal system", but
rather as a step for step improvement of an instrument. Before I read
your manuscript I would not have put it in just those words. But your
formulations and clarifications by examples and also your analogy
with Darwin's theory helped me to see clearer what I had in mind.
      From September on I shall be for a year at the Stanford Center. I
hope that we shall have an opportunity to get together and talk about
problems of common interest.
With best regards yours,

Rudolf Carnap (signed)