Be that as it may, many mathematicians in the early 1900’s were reluctant to make so sharp a break
with tradition as axiomatic set theory seemed to demand. Furthermore, they felt, on esthetic grounds,
that a mathematical theory of sets should describe all the things—and only those things—which our
intuition recognizes to be sets. Among them was Bertrand Russell; in his efforts to reinstate intuitive
set theory, Russell was led to the idea that we may consider sets to be ordered in a hierarchy of
“levels,” where, if A and are sets and A is an element of , then is “one level higher” than A.
For example, in plane geometry, a circle (regarded as a set of points) is one level below a family of
circles, which, in turn, is one level below a set of families of circles. This basic idea was built by
Russell into a theory called the theory of types, which can be described, in essence, as follows.
Be that as it may, many mathematicians in the early 1900’s were reluctant to make so sharp a breakwith tradition as axiomatic set theory seemed to demand. Furthermore, they felt, on esthetic grounds,that a mathematical theory of sets should describe all the things—and only those things—which ourintuition recognizes to be sets. Among them was Bertrand Russell; in his efforts to reinstate intuitiveset theory, Russell was led to the idea that we may consider sets to be ordered in a hierarchy of“levels,” where, if A and are sets and A is an element of , then is “one level higher” than A.For example, in plane geometry, a circle (regarded as a set of points) is one level below a family ofcircles, which, in turn, is one level below a set of families of circles. This basic idea was built byRussell into a theory called the theory of types, which can be described, in essence, as follows.
การแปล กรุณารอสักครู่..
