ABSTRACT
Coping with uncertainty, then, is the essence of responsible decision-making. Measurements always contain an element of error. The most exact description that may be offered for any physical item is still only an approximation; and this is all the more true in socio-economic quantifications. The evidence supporting models of an evolving system will be taken from only some of the instances within the range of any conclusion, that is, historical data; a degree of uncertainty will be attached to the remaining cases, that is, the unobservable future. Certainty is the degenerate case of uncertainty, wherein it may be asserted that the future is characterised by a sequence of events each of which carries probability unity of occurrence. Risk characterises a perception of the future when there is knowledge of the law which governs the realisations of events but this law contains a random element of known behaviour.
