Medical issues in historical demography.

For the demographer and economic historian all movements of population are important and deserve, so far as possible, to be explained; but for the student of social and medical history the modern rise of population is a unique event whose interpretation is not only of the greatest historical interest but is also essential to an understanding of some of the most formidable contemporary problems. The distinction between the earlier recurrent changes of population and the modern rise is of particular significance in the eighteenth century. The methods as well as the aims of enquiry are different according to whether the increase in numbers is regarded as analogous to that in previous periods (given particular but not necessarily unique significance because of its coincidence with the Agricultural and Industrial Revolutions), or whether it is considered as the beginning of the modern expansion whose dimensions and continuity distinguish it from all previous changes. If eighteenth-century growth is no more than the most remarkable of many movements of population, it is permissible to argue by analogy and to invoke the same kinds of explanations as are accepted for earlier periods. This treatment has been adopted by some economic historians, for example when a decline of mortality has been attributed to cyclic changes in the behaviour of infectious diseases.1 But if the eighteenth century saw the beginning of the modern rise of population such explanations are clearly inadequate, for as the event was unprecedented so too, it seems reasonable to believe, must be the explanation for it. There is no serious doubt that in Britain the modern rise of population did begin during the eighteenth century. It was certainly well established before registration of births and deaths (1838) and even at the time of the first census (1801) the increase in numbers was much greater than that which occurred in earlier periods. For the purpose of interpreting the modern rise of population it is unnecessary, and probably impossible, to state precisely when it started. It is sufficient to know that whatever the explanation in the early years of the eighteenth century, at some time before its end the first phase of the unique expansion had begun.