The consolidation of economics as an academic discipline is commonly associated with the crystallisation of a formalistic, ‘marginal’ methodology out of the discursive literature of classical political economy. Yet this was only the final phase in a long process stretching back to medieval, and even ancient, times, a process in which ideas now identified as economic were formulated in inseparable connection with branches of inquiry which were subsequently to become located within other social science disciplines. The relation of economics and geography in Western thought provides a prime example of the common roots of the different social sciences: in ancient times, that most economically-minded writer, Xenophon, was at the same time arguably its most geographically conscious as well; the topics of economics and geography were, in medieval times, both classed within the same disciplina, namely rhetoric; and when, in the early modern period, the demand arose for an education of a more practical and less doctrinal aspect, a notable response from within the scholastic system was the expansion of the rhetoric syllabus to accommodate more material of topical geographical, and inevitably also economic, interest (see Dainville 1940). An example of the enthusiasm with which this educational innovation was received is provided by the English writer William Petty, best known as a founding father of English political economy, who singles out the study of geography as first on the list of motives which prompted him to undertake his further education (PP Vol. II: 2461). Indeed, it has long been recognised that Petty’s writings provide ample

illustration of the inextricably linked trajectory of early modern geographical and economic ideas. It is over a century, for example, since his editor commented that ‘Petty’s thought exhibits much affinity’ with that of Von Thünen, the acknowledged pioneer of spatial economics (Hull 1899: lxv). Since that time, a number of historians of economic thought have drawn attention to what they perceive as Petty’s anticipation of the concept of locational rent (for references see below), and some have even declared that the roots of Petty’s economic methodology as a whole lie in his experience as a land surveyor (see, for example, McNally 1988: 46-48, Poovey 1994: 20-32, Poovey

1998: ch. 3 and Wood 2002: 161). But though a small specialist literature exists on the spatial-economic analysis of Cantillon, Steuart and Smith (Hébert 1981; Beckmann 1981; Stull 1986; Fernández López 2002), it appears that there has hitherto been only one systematic attempt from within the economics discipline to draw attention to the relevance of Petty’s writings to the intellectual ancestry of modern spatial-economic analysis (Pinto 1997). This neglect contrasts with the substantial interest shown by a number of French authors, who, from within the neighbouring fields of geography and demography, have generated a whole literature on the spatial-economic dimension of Petty’s thought – a literature which has yet to gain currency in the Englishspeaking world (see, in particular, Goblet 1930, Dockès 1969: 132-57 and Reungoat 2004: 121-34). There was indeed ample reason why Petty should display acute conscious-

ness of the spatial dimension of socio-economic activity, since it was he who supervised the most extensive land survey of his time, the celebrated ‘Down Survey’ of Ireland. In what follows, the spatial aspect of Petty’s economic thought will be placed in the context of this biographical background, showing how this context, and in particular its bureaucratic-military and predatory colonialist aspects, drew him ineluctably towards ever greater confidence in his notorious scheme to transfer the bulk of the population of Ireland into England, in connection with which he drew together strands of economic and geographical thought that remain intertwined till today, most notably in the marginalist sub-discipline of spatial economics.