Fuzzy concept

A fuzzy concept is a concept of which the boundaries of application can vary considerably according to context or conditions, instead of being fixed once and for all. This means the concept is vague in some way, lacking a fixed, precise meaning, without however being unclear or meaningless altogether. It has a definite meaning, which can become more precise only through further elaboration and specification, including a closer definition of the context in which the concept is used.

A fuzzy concept is understood by scientists as a concept which is "to an extent applicable" in a situation, and it therefore implies gradations of significance. The best known example of a fuzzy concept around the world is an amber traffic light, and indeed fuzzy concepts are widely used in traffic control systems. Engineers, statisticians and programmers nowadays often represent fuzzy concepts mathematically using fuzzy variables, fuzzy sets and fuzzy values. Since the 1970s, the use of fuzzy concepts has risen gigantically in all walks of life.

The ancient Sorites paradox first raised the logical problem of how we could exactly define the threshold at which a change in quantitative gradation turns into a qualitative or categorical difference. With some physical processes this is relatively easy to identify. For example, the boiling point of water (where it turns into steam) is 100 °C or 212 °F (the boiling point depends partly on atmospheric pressure, which decreases at higher altitudes). With many other processes and gradations, however, the point of change is much more difficult to establish. The Nordic myth of Loki's wager suggested that concepts which lack a precise meaning or precise boundaries of application cannot be usefully discussed at all. However, the 20th century idea of "fuzzy concepts" proposes that "somewhat vague terms" can be operated with, since we can explicate and define the variability of their application, by assigning numbers to it.

The intellectual origins of the idea of fuzzy concepts have been traced back to a diversity of famous and less well known thinkers including Eubulides, Plato, Cicero, Georg Wilhelm Friedrich Hegel, Karl Marx, Friedrich Engels, Friedrich Nietzsche, Max Black,Jan Łukasiewicz, Alfred Tarski, Stanisław Jaśkowski and Donald Knuth. This suggests that awareness of the existence of concepts with fuzzy characteristics, in one form or another, has a very long history in human thought.

...
Wikipedia