Re: fuzzy logic and probability

S. F. Thomas (
Tue, 9 Jul 1996 12:24:04 +0200

Earl Cox ( wrote:
: In article <4rfsju$>
: (Jakobs) writes:

: >I was wondering if those so-called membership functions can
: >be regarded as some kind of probability functions?
: >I have to admit I don't know much about fuzzy logic, but
: >at a first glance it seemed to me that there is a close
: >relationship between fuzzy logic and probability theory.
: >Am I right?

: Starting out a reqquest in this forum with "so-called" membership functions
: will not produce a wealth of information your way. Further, most of us are so
: god damn tired of debating fuzzy versus probabilty with people who haven't
: even bothered to learn anything about fuzzy logic (like yourself) that we
: flatly refuse to do it. This is not a flame, its just a howl of indignation,
: anger, and frustration.

: Go read the FAQ. Go get Kosko or Klir's excellent books on Fuzzy Logic.
: Learn something about the subject.

However provocatively phrased, Mr. Jakob's question is a fair one.
You can of course claim fuzzy logic to be whatever you want it
to be, axiomatized in whatever way seems preferred by two or more
fuzzicists at the moment. However, to the extent that fuzzy logic
attempts to model certain aspects of natural-language semantics,
there is an external reality out there that exists quite independently
of any received theory of the moment. It is by reference to its application to
that empirical domain that fuzzy logic as theory, as opposed to
axiomatic construct, must ultimately be judged. If "membership
function" stands for anything in the real world, in principle observable,
then Mr. Jakobs is entitled to the scepticism implicit in his
infelicitous choice of phrase. However heartfelt the anger and
frustration which propel it, a howl of indignation in response
is no defense of any theory that purports to model a real-world,
observable phenomenon.

Is he right, or not? If not, why not? Or is the refusal to debate
the subject not limited to those who haven't bothered to learn anything
about fuzzy logic?

: Earl Cox

S. F. Thomas