In this paper we try to provide an analytical basis for the theory of fuzzy sets. The main idea is to introduce the the notions of consensus sets and subjective variables, which strongly resemble, respectively, the events and random variables in the probability theory. The resemblance is a natural consequence from the fact that one of the most important roles of the fuzzy set theory is to present a method for the analysis of the uncertainty originated in human subjectivity while the probability theory for that of randomness.