ABSTRACT
This chapter demonstrates that the subjectivity is an inevitable component in any measure of uncertainty. It explains two different approaches to uncertainty, the frequentist and the subjective, and shows that the frequentist offers little help in quantifying risk and that, in any case, the subjective approach subsumes it. The frequentist approach is extremely useful, it should be clear that authors cannot generally rely on it to measure uncertainty. The subjective approach accepts unreservedly that different people may have vastly different beliefs about the uncertainty of the same event. In the law there is even a quasi-legal distinction made between them: frequentist measures of uncertainty are considered scientific and hence suitable to be presented in court; subjective measures are considered nonscientific and hence not suitable for presentation in court. Any attempt to measure uncertainty inevitably involves some subjective judgment. There is no truly objective frequentist approach.
