(1) Construct a mathematical model of a certain class of human decisions. Of course the model will omit all creative thought on the part of the people being modelled, because it is not known how to model creative thought.
(2) Classify decisions made in the model as ‘rational’ or ‘irrational’ depending on some unacknowledged cultural criterion. (Again, this cannot possibly reflect the real distinction between rational and non-rational processes.)
(3) Invent an experiment in which humans are asked to make decisions in an artificial situation in which one can measure whether they are ‘rational’ or ‘irrational’ according to the criterion of (2). It will turn out that they (or some target group among them) are ‘irrational’.
(4) Denigrate the target group, or human beings in general (except perhaps the experimenters and whoever the above-mentioned cultural criteria are designed to flatter), as being unfit to make their own decisions.