1.5. THE CLASSIFICATORY ASSUMPTION.

After I had studied science and particularly biological science for some
years, I became a teacher in a school for boys. I found it necessary to
supplement my untutored conception of teaching method by a more
systematic knowledge of its principles and methods, and I took the
courses for the diplomas of Licentiate and Fellow of the London College
of Preceptors which happened to be convenient for me. These courses
included some of the more elementary aspects of psychology and logic and
set me thinking and reading further. From the first, Logic as it was
presented to me impressed me as a system of ideas and methods remote and
secluded from the world of fact in which I lived and with which I had to
deal. As it came to me in the ordinary textbooks, it presented itself as
the science of inference using the syllogism as its principal
instrument. Now I was first struck by the fact that while my teachers in
Logic seemed to be assuring me I always thought in this form;-

"M is P,
S is M,
S is P,"

the method of my reasoning was almost always in this form:--

"S1 is more or less P,
S2 is very similar to S1,
S2 is very probably but not certainly more or less P.
Let us go on that assumption and see how it works."

That is to say, I was constantly reasoning by analogy and applying
verification. So far from using the syllogistic form confidently, I