Limitation can usually be measured on a quantitative scale as an insufficiency of something. In terms of human problems this "something" may be causal. If the cause is not quantifiable, its effect may be. Quantification of limitation is a vital step in problem identification, analysis and remedial action. For example, a lack of aid to developing countries may be quantified financially against specific projects or against general budget deficits. A lack or, quantitatively expressed, insufficiency of infrastructure is more difficult to state. Many problems arising from limitations lack statistics. This is due to the presence in problems of a great number of variable limits or constraints. Some of these may be inputs, others may be structural. Complex interrelationships of limits require computer modelling and heuristic methodologies of approaching quantified formulations. An example is world growth models as used in Club of Rome and similar global forecasts. However, there has been no general agreement on global limits, exactly stated, in food, population, resource and pollution problems, for example.
Whether in natural or human resources, there is a point beyond which "more" is really not feasible at a given time. This applies not only to the limits of natural resources available to be exploited on the planet, but also to the capacity of urban areas for expansion, of industries for growth, of individuals for rapid change. Although it is well to avoid drawing false limits to living out of a feeble imagination or weak faith, it is equally foolish to pretend that existence is an inexhaustible well.
The concept of limitation illustrated in dressed-up but simplistic supply and demand models is frequently expressed by arbitrary numbers in both sides of the equation. They are arbitrary because there is no scientific knowledge that is incontrovertible and that provides a 100% accurate forecasting basis. In addition, applied science (that is, human technology) keeps pushing back the limits. For example, the diminishing resources of this planet may be augmented by resources on other planets. Human intelligence is being augmented already by computer artificial intelligence. And human development itself may go beyond its present limits by the employment of behavioural re-education, by genetic engineering, and by new forms of political and social organization developing in a new age.