Two opposed views of population dominated the literature in the seventeenth and early eighteenth centuries. William Petty, who was one of the founders of modern demography, as well as an important pioneer of economics, was perhaps the most convincing supporter of the 'populationist' view. He claimed that there was plenty of underused land in both England and France (Petty, 1690: 285), and that there were also many opp­ ortunities to employ additional workers outside agriculture. He even advocated shifting most of the population of Ireland to Britain, in order to increase the population of Britain (Petty, 1690: 285ff and 1687, passim). An increase in population would, he claimed, allow an increase in both output and tax revenue.