Re: Bivalent or Monovalent

christopher lacey (
Mon, 29 Jan 1996 17:30:16 +0100

On Fri, 26 Jan 1996, Ian Goddard wrote:

> Non-fuzzy Aristotelian logic is called Bivalent to indicate that it allows
> for only one of two values, A or ~A, black or white, 1 or 0.
> However, I think because Aristotelian logic allows for only ONE value at a
> time -- if it is A then it is A, i.e., it is 100% A and 0% ~A -- that
> Aristotelian logic is actually * monovalent.*
> Fuzzy logic is bivalent because it allows for an array of degrees between
> TWO values, and teach degree occupies these two values at the same to a
> different degree relative to the others, unlike Aristotelian logic which
> occupies only one value at a time.
> I think Aristotelian logic is monovalent, and fuzzy logic is bivalent with
> an array of degrees between the two values. Do you agree ?
At first glance I would agree with you suposition that
Aristitilial Logic be considered monovalent, but in considering the
definition of the word valent (and the nature of fuzzy logic when three or
more values are considered at the same time), I would propose that
Aristitilian logic still be considered *monovalent*, (because, just as you
said, no two true values can occupy the same space or level at the same
time A=100% and A~=0%). Fuzzy Logic on the other hand should still be
considered *multivalent* for the simple reason that: A=30% and B=25% and
C=40%. But, you might say, not only are these multiple truth values
occupying the same space, but they don't even add up to 100% (95%). From
my point of view, why should they add up to 100%, nothing else in the real
world does either. I would also add in closing that fuzzy statements tend
to eschew absolute propositions (which even an array between two degrees
would seem to imply as the domain of an absolute, unless I have
misunderstood you proposal) and instead favor a relative position to the
I would really enjoy feedback on the ideas put forward here,
because in the process of responding to this post I have clarified some
of my own thinking, but a reality check is still good to have.

Chris Lacey