In standard mathematics, the proposition zero belongs to the set { 0 } is regarded as simply true, while proposition one belongs to the set { 0 } is regarded as simply false. Some mathematicians, computer scientists, and philosophers have been attracted to the idea, though, that a proposition might be more or less true, rather than simply true or simply false.
In mathematics, this idea can be developed in terms of fuzzy logic. In computer science, it has found application in artificial intelligence. In philosophy, the idea has proved particularly appealing in the case of vagueness.
