On the first look, fuzzy logic is an efficient way in dealing with uncertainty. It allows to store vague information into a float variable which allows similar to a color gradient a realistic description of the world. The problem is, that in a concrete example, Fuzzy logic has the tendency to become a subjective opinion panel which makes it a bad idea for practical applications.
In the example, two people are asked if the glass of water is full or not. The answer is different and not predictable. Person1 will judge, that the glass is empty, because he has a pessimistic membership function. But Person2 has a different opinion and will say “yes, the glass is full”.
The example was mentioned to show, that Fuzzy logic doesn't solve the problem with uncertain knowledge, but it will result into an unreliable system. Is there a way to make the concept more trustworthy and judge objective about the content of the bottle?