Not to Be Cited Without the Author's Permission

David Harvey: Explanation in geography Ron Johnston1 School of Geographical Sciences, University of Bristol This has been prepared for a book on ‘Key Texts in Human Geography’ NOT TO BE CITED WITHOUT THE AUTHOR’S PERMISSION The 1960s was a turbulent decade in geography: by its end, the discipline incorporated practices very different from those deployed ten years earlier. Building on discontent with disciplinary practices born of experience of interaction with scholars from other disciplines in the American Office of Strategic Services during World War II (Barnes and Farrish, 2006), a number of geographers – notably a cohesive group of faculty and graduate students at the University of Washington, Seattle – began in the mid-1950s to promote a very different vision of geography (both physical and human) based on the ‘scientific methods’ deployed by physicists and, in the social sciences, economists. By the early 1960s, this group was rapidly attracting adherents at a number of major US graduate schools, and in 1963 one observer-participant claimed that the ‘revolution’ promulgated from Seattle was successfully over. Almost contemporaneously, a similar ‘revolution’ was taking shape in the UK, based at the University of Cambridge. Two recently-appointed faculty members – Dick Chorley and Peter Haggett – were attracted to the ‘scientific model’ (which Chorley had encountered and adopted while a geology graduate student in the USA), and they began to teach related material, mainly statistical methods, in their introductory practical classes for geography undergraduates. One of the demonstrators in the first year for that course (in 1960) was a postgraduate student working in historical geography – David Harvey. Although the shift in geographical practices these two groups were advancing is often referred to as the discipline’s ‘quantitative revolution’, it involved much more than just applying mathematical and statistical techniques to geographical data. It was fundamentally a ‘theoretical revolution’, which changed the entire mind-set of how research was to be undertaken and new knowledge presented. Words such as ‘theory’, ‘model’, ‘hypothesis’ and ‘law’ become common in the geographical lexicon, as researchers strove to produce knowledge that was cumulative in the sense generally appreciated by physical scientists, building on earlier research to advance their ability not only to explain the world that they observed but also to modify (improve) it. 1 My thanks to Les Hepple, Tony Hoare, Kelvyn Jones, Charles Pattie and Eric Pawson for valuable discussions of this essay and comments on draft versions. When a discipline is experiencing such major change, new teaching materials are needed to introduce students to (and justify) the ‘revolutionary’ practices. Introductory textbooks usually lag behind such changes – publishers have to be convinced that there is a viable market for ‘revolutionary tracts’! This was so with the 1960s ‘new geography’. The first books clearly enunciating the changes appeared in 1965 (Haggett’s Locational analysis in human geography – this was very much a publisher’s gamble on the shape of the discipline’s future – and Chorley and Haggett’s edited volume Frontiers in geographical teaching: Bunge’s, 1962, monograph on Theoretical geography had only a limited circulation, although a revised edition in 1966 attracted wider attention). A spate of texts oriented towards the ‘revolution’ only emerged some five years later. It included David Harvey’s Explanation in geography, the product of almost a decade teaching undergraduates at the University of Bristol about the ‘new’ scientific basis to geographical work, building on discussions with colleagues in Sweden and the USA (where he spent considerable time during the decade); as he puts it in the Preface, writing the book was part of his learning experience as he developed teaching materials. Harvey’s book – like that of the other ‘revolutionaries’ he joined – reflected a deep dissatisfaction with geographical practices experienced when he was an undergraduate and in his interactions with researchers immediately thereafter. For him, too, quantification was necessary but far from sufficient: measurement was a requisite tool, but much more important was for both human and physical geographers to appreciate and deploy the philosophy which under-pinned the ‘fantastic power’ of the scientific model. Hence he explored – and wrote a book (he termed it an ‘interim report’) about – ‘the ways in which geographical understanding and knowledge can be acquired and the standards of rational argument and inference that are necessary to ensure that the process is reasonable’ (p. viii). This exploration took him into a literature previously almost entirely ignored by geographers, so that although he includes plentiful references to a small number of geographers (especially those instrumental in fomenting the ‘revolution’, but also two – Hartshorne and Sauer – whose views he largely opposed) his ‘Author index’ indicates how heavily he drew on philosophers of science – Ackoff, Braithwaite, Carnap, Churchman, Hempel, Kuhn, Nagel, Popper (to a lesser extent; falsification is very summarily dismissed) and even Einstein and Russell (although neither Ayer nor Wittgenstein is mentioned) – as well as mathematicians/statisticians such as Anscombe, Blalock, Fishburn, Fisher, Krumbein, Sneath, and Sokal. From the outset, Harvey focused on explanation. After a brief introductory chapter setting out his main concern as being with methodologies – with how geographers should produce explanations – rather than philosophies of science (despite their foundational role), he moved to a discussion of what explanation means. It is defined as ‘making an unexpected outcome an expected outcome, of making a curious event seem natural or normal’ (p.13) because it can be shown to be generated by similar processes and in similar conditions as previous events of the same type. Harvey’s concern was with ‘rational explanation’, statements verifiable by others because the procedures involved in their production can be repeated and/or are open to scrutiny. It is a ‘formal procedure … [the] hard inner core of methodology’ (p.23). Following that brief framework-setting introduction (26 pages only), the remainder of the book comprised five main sections dealing with: explanation in geography; 2 theories, laws and models; languages; ‘models for description in geography’; and ‘models for explanation in geography’. At the outset he contrasted (in an oft-reprinted diagram) the inductive or ‘Baconian’ path to explanation with his preferred deductive route, which proceeds through the establishment of a model representing the researcher’s image of the world, the derivation of hypotheses regarding some aspect of that image, testing the hypothesis’s validity, and the formulation of theories and laws synthesising the knowledge gained – from which revised models can be derived. Four terms/concepts stood out in the lexicon associated with this route to explanation. Hypotheses were presented as logically consistent ‘controlled speculations’. They can never be tested absolutely – conclusions are always provisional – but they guide the production of scientific knowledge in a rigorous (and hence replicable) way. The key outcomes of testing hypotheses are laws and theories. Laws are sometimes presented as universal truths – statements whose validity is constrained by neither time nor space. It is never possible to reach such conclusions, but scientists act as if they can, using their findings as statements of the current ‘conventional wisdom’ encapsulating what we already know and providing the foundations for further scientific exploration. They are rigorously produced provisional conclusions representing the contemporary state of knowledge. For geography (especially human geography, although much physical geography at the time – such as the Davisian model of landscape evolution – similarly lacked rigorous underpinnings), they contrasted sharply with the ‘explanatory sketches’ traditionally offered as accounts of ‘observed reality’. The production of laws in geography, according to Harvey, involved searching for ‘hidden order within chaos’: because the results of such searches are likely to be provisional/tentative, Harvey suggested that geographers might prefer the concept of ‘law-like statements’, general claims that are both ‘reasonable with respect to experience and consistent with respect to each other’ – a coherent body of knowledge corresponding with the observed ‘reality’. Theories are systems of linked statements about defined subject matter. These may be entirely closed systems – as with Euclidean geometry; they may be sets of deductive statements derived from accepted axioms; or they may be less-formally stated ‘sketches’. They are not just speculative ideas – as sometimes implied in vernacular uses of the term: anyone can fabricate such a ‘system of apparent wisdom in the folly of hypothetical delusion’ (p.97: Harvey is quoting James Hutton via Chorley). Scientific theories take ‘such speculations and transform ... them from badly understood and uncomfortable intrusions upon our powers of ‘pure’ objective description into highly articulate systems of statements of enormous explanatory power’ (pp. 87-88). Various types of theory extend along a continuum from highly-formalised, internally- closed sets of statements (as with many forms of mathematics and logic), through sets of statements which are only partial (either

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