A programme, organization or activity, or individual and collective human development potential, may be limited either by internal or by external limitation, or by both. Internal limitation may be inherent, constituted by the very nature of human organization and individual and systemic capacities. Thus a primitive society may organize healing functions via ritual, shamanism, witch doctors and other activities; but without real medical knowledge it is nonetheless completely exposed to disease. Internal limitations may also be accidental or circumstantial. It can be said, for example, that inadequate medical services in developing countries can be remedied by training indigenous peoples in medicine, assuming there is no insurmountable intellectual or cultural obstacle to this education. Extrinsic or external limitations may be illustrated by the isolation of a community so that it cannot participate in medical advances. Such a limitation may be presented by natural circumstances. Other external limitations may be imposed by human activity, for example, economic or military subjugation of peoples so that their medical needs are not met.
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.