The aggregate rule of evidence: fuzzy set theoretical approach

There are at least two kinds of uncertainty: randomness and fuzziness. Correspondingly, there are at least two major methods for aggregate evidence: Bayesian and fuzzy set theoretical approaches. A comparative behavioral study is given. The problem about human conservatism in inference is discussed. Some early research has shown that people are conservative information processors primarily because they misaggregate evidence. This, in the author´s view, is a questionable assertion. The concept of linguistic aggregation is briefly explained