The Dictionary of Human Geography (167 page)

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Authors: Michael Watts

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rank-size rule
An empirical regularity iden tified in the city size distributions of some countries and regions. Generally, if the cities are ranked from 1 (the largest) to n (the smal lest), then the population of any city k can be determined from the equation: (NEW PARAGRAPH) Pk = Pi/k, (NEW PARAGRAPH) where P1 is the population of the largest city and Pk that of the city ranked kth. The steep ness of the relationship between size and rank is incorporated by raising k to the power b; that is, kb. No convincing explanations for the rule?s existence have been developed, how ever, nor for variations in the parameter b between regions (e.g. why the fifth largest city is smaller, relative to the largest, in some places than it is elsewhere). rj (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Carroll (1982). (NEW PARAGRAPH)
raster
Raster is a GIS data structure akin to placing a regular grid over a study region and representing the geographical feature found in each grid cell numerically: for example, 1 = podsol, 2 = clay and so on. Rasters are asso ciated with remote sensing, image processing and dynamic modelling, and are easily mani pulated using map algebra (e.g. multiplying geographically corresponding cell values in two or more datasets) and neighbourhood functions (e.g. returning the sum of values in 3 x 3 cell window). Rasters are simple but often voluminous. Patterns in the data are therefore compressed using run length encoding, quad trees or wavelets. rh (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) DeMers (2001). (NEW PARAGRAPH)
rational choice theory
A normative the ory of individual decision making, claiming that human action is motivated by getting the most for the least. On the one hand, individ uals strive to achieve an unlimited set of ends where each end is associated with a different level of satisfaction or utility, but, on the other hand, they possess only a limited means to realize those ends. The role of the rationality postulate is to ensure that the best ends that is, those yielding greatest individual satisfac tion are chosen given the constraint of lim ited means. Often couched in terms of the mathematics of constrained maximization, the problem of making the best choices is formally shown to reduce to a formal set of consistency requirements (Hahn and Hollis, 1979). Those requirements define rationality in the sense that if any one of them is contra vened, the choice is not rational. (NEW PARAGRAPH) The historical antecedents of rational choice theory are with the British classical econo mists, but it is now most closely associated with their successor, neo classical econom ics, and a maverick strain of Marxism (ana lytical marxism). Within economics, it is not just economic acts that are explained by rational choice. The University of Chicago, Nobel Prize winning rational choice econo mist Gary Becker (1930 ) uses the theory to explain all human acts from birth (the decision to have a child) to death (choosing suicide) and everything in between, including racial discrimination, committing crime, going to school, falling in love and filing for divorce (Becker, 1976). Nothing falls outside the ?lore of calculated less or more?. The rational choice assumption is deployed across the social sciences, including sociology (rational individuals choose their social class), political science (scenarios of geopolitical brinkman ship modelled via game theory) and anthro pology (cultures are ?a collection of choice making individuals?; Burling, 1962, p. 811). Within human geography, rational choice theory is most frequently found in economic geography and, in particular, in the formal location theory associated with regional science. Its role is to impose a determinant order on spatial arrangements, allowing the theorist to make scientific claims to precision, exact inference and predictability. (NEW PARAGRAPH) There have been many criticisms of the rationality assumption, and they frequently focus on the unrealistic characteristics att ributed to the rational actor (sometimes described in the gendered language of Homo economicus, or ?rational economic man?): per fect knowledge; unyielding egoism; independ ent preferences; the ability and desire to maximize utility (minimize costs); and pursuit of a single goal (see satisficing behaviour). Such criticisms are often moot, however, because the rationality postulate by its very construction is empirically untestable, a nor mative rather than a ?positive? theory, and therefore charges of unrealism have little (NEW PARAGRAPH) purchase. More incisive are those criticisms that tackle the normative character of the pos tulate by arguing that it offers an unappealing vision of the world. Karl Marx (1818 83) (see Marx, 1976 [1867], ch. 6) satirizes rational choice by invoking the invidious character of ?Mr Moneybags?, and the American institu tional economist, Thorstein Veblen (1857 1929) (see Veblen, 1919, p. 73), makes it clear that ?economic man? is not even close to human: he is a ?homogenous globule of desire . . . with neither antecedent nor conse quent. He is an isolated, definitive human datum, in stable equilibrium except for the buffers of the impinging forces that displace him in one direction or another? (see institu tional economics). Another line of attack is to criticize the postulate?s intellectual origins and consistency. Mirowski (1989) does this by locating both the conceptual corpus of the rational actor and its associated mathematical techniques within the nineteenth century physics of energetics. In other words, the ration ality postulate was brought to social science via re description: it is a metaphor. Apart from the fact that energetics itself was short lived and quickly superseded, Mirowski argues that those economists who took up the metaphor never successfully transferred the core relations from physics to economics. The gap is oftwo different worlds, revealing a contradiction at the very heart of the project. tb (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Barnes (1996, chs 2 and 3). (NEW PARAGRAPH)
realism
Realism comes in many forms, and realists vary widely in what they are prepared to be realist about. At its most general, realism entails belief in an external world that exists and acts independently of our knowledge of it or beliefs about it. The weakest form of real ism simply asserts this belief, but is unspecific about what exists. A ?common sense realism? asserts the existence of everyday objects, such as trees, stones or chairs. All of us are probably realists at this level. In the humanities, realism identifies a broad literary movement that iden tified art in general, and literature in par ticular, with the truthful representation of the world through the meticulous and dispas sionate observation of contemporary life. Its central arch spanned the mid nineteenth and early twentieth centuries from the novels of Gustave Flaubert (who in fact rejected the label) to those of Henry James and some writers later re described the project as a ?naturalism?. Thus Emile Zola argued that in matters of cultural criticism and literary description ?we must imitate the naturalists?. It is this possibility of naturaLism that has propelled realism in philosophy, science and the social sciences (Bhaskar, 1998 [1979]) (NEW PARAGRAPH) ?Scientific realism? asserts the existence of various observable and unobservable entities of which it claims to be capable of giving the best representations. Many scientific realists sub scribe to an ?entity' realism, which asserts the existence of many, well established theoretical entities (various atomic particles, for example), but not necessarily to a ?semantic' realism, or belief in the truth of any one theory about such entities that correctly represents or mirrors ?the way things really are? (Hacking, 1983). There are also profound differences amongst scientific realists on notions of truth, reference, inference and explanation (Psillos, 1999). Matters are a little simpler in the social sciences in that a particular version of realism, critical realism, has become dominant and the focus of most debate. This is a version particularly associated with the work of Bhaskar (1986, 1989, 1998 [1979]) and Sayer (1992 [1984], 2000). (NEW PARAGRAPH) Early formulations of critical realism typic ally developed its main elements by asking what reality must be like to make the existence of science and its successes possible, which leads to a critique of the impoverished assum ptions underlying empiricism or positivism. Critical realists reject the possibility of basing science on a ?flat? ontology of atomistic sense impressions. They make more complex onto logical claims, distinguishing the empirical (events that we experience), the actual (events that happen whether we experience them or not) and the real (a deeper dimension of objects, structures and generative mechanisms that produce events). (NEW PARAGRAPH) Critical realists also reject a restricted, posi tivistic view of causality as the constant con junction of observable events (a ?regularity view? of causation): ?If A, then B? (see law, scientific). Critical realists point out that the social sciences usually deal with open systems, rather than closed systems that can be artifi cially produced in a scientific laboratory. Although regularities are rare in such open systems, this does not mean that causes are not at work. Causes are thus best thought of as tendencies of objects, with distinctive powers in virtue of their essential structures, to act in certain ways. However, it is con tingent whether and how those powers are activated in different combinations in different contexts to produce varying effects. Predictive success is thus difficult to achieve, but it may be possible to identify the underlying causal mechanisms beneath the flux of surface phe nomena. The distinctive mode of inference to such mechanisms is called variously abd uction, retroduction or inference to the best explanation. (NEW PARAGRAPH) Powers are also often ?emergent? in the sense that the powers of objects or structures to produce effects are not reducible to those of their constituents (e.g. the powers of classes or groups may be more than the sum of the powers of their individual members). Reality is thus stratified in the sense that powers and mechanisms operative in one strata are not simply reducible to those of a lower strata. (NEW PARAGRAPH) Critical realists also make an important dis tinction between necessary and contingent properties or relations. Objects are necessarily or internally related if they are what they are by virtue of their relationships to each other (e.g. the relationship between land lords and tenants each requires the other in order to be what it is). What we term ?structures' are made up of such networks of internaL reLations and define positions to be occupied by actors. However, it is often contingent who occupies these positions (landlords may be young or old, male or female etc.). abstraction is defined as the key procedure for identifying such structures by disentangling what are necessary from what are contingent relationships. (NEW PARAGRAPH) Critical realism also offers a distinctive per spective on familiar agency structure dualisms that bedevil human geography and, indeed, the humanities and social sciences more gen erally (see human agency). Individual agency presupposes a social structure, and vice versa, but social structure and agency are ontologic ally distinct levels with different properties and causal powers (e.g. social structures are enab ling and constraining; individuals have self consciousness and reflexivity). Individuals may reproduce social structures through their everyday practices and understandings, but the ?critical' moment in critical realism lies in the belief that bringing underlying structures and their unconscious reproduction to the level of consciousness opens the way for eman cipatory critique and social change. (NEW PARAGRAPH) Critical realism provides a philosophical framework for social science, but it does not prescribe a particular methodology. It is compatible with a range of quaLitative tech niques and quantitative techniques that can aid the identification of causal structures, including hermeneutic and interpretivist approaches. (NEW PARAGRAPH) Realism contends with various forms of anti realism in the guise of postmodernism, pragmatism and social construction. A key focus of debate concerns the meaningfulness of referring to a reality outside of the concep tual systems that we use to talk about it. From a pragmatist angle, Rorty (1979) argues that it is meaningless to talk about conceptual systems representing or ?mirroring? an extra linguistic reality (see also representation). In the soci ology of science, radical constructivists argue that reality is not something existing outside of scientific discourse, but is essentially a discur sive construction (see social construction). Critical realists typically respond to such claims with the argument that although social reality may be highly concept dependent, this does not mean that it is concept determined in such an idealist way. (NEW PARAGRAPH) The division between realism and anti realism runs through most areas of social science, including marxism and feminism. However, the divisions should not be exagger ated. A ?realistic constructivism? would recog nize both the ways in which scientific discourse is powerfully shaped by social interests and cultural values, and the constraining role of objective material realities. The relationship between discourse and reality is an interactive and reflexive one. At a more general level, Sayer (2000) has argued powerfully that crit ical realism occupies a ?Third Way? between the untenable extremes of empiricism on the one hand and postmodernism on the other. Certainly, critical realism was a vital interven tion in the critique of spatial science and the refinement of Marxist geography in particu lar; it was also invoked to underwrite struc turation theory. There was a lively debate about ?the difference that space makes? to explanation under the sign of critical realism (Sayer, 1985). Spatial relations are clearly important in analysing the contingent circum stances, the specific combinations of condi tions under which causal powers might be realized, but several geographers argued that spatial relations also enter into the very consti tution of the social structures involved (see space). For a time, critical realism also held out the prospect of a plenary geography, drawing human geography into a conversation with physical geography through a commit ment to a common and recognizably ?scientific? programme. That was never achieved: by the time most physical geographers had become interested in realism, most human geographers had started to ask critical questions about its claims and consequences (e.g. Yeung, 1997), and many of them soon moved on to explore philosophies outside the confines of the phil osophy of science, which were typically treated as resources rather than rule books. kb/Dg (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Brown, Fleetwood and Roberts (2002); Carter and New (2004); Danermark, Ekstrom, Jakobsen and Karlsson (2002); Sayer (2006). (NEW PARAGRAPH)

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