Friday, 12 August 2011

The Use and Abuse of Tansley's concept and term

Peder Anker (2001) has written one of the best books on the history of ecology and the ecosystem concept I have come across so far. However, he makes one claim I dispute:
"Tansley's Figure 7, "The associative network of the mind," is particularly important to the argument of this book. I will later argue that Tansley projected this model of the mind into ecology, and that this figure thus represents the very origin of the ecosystem concept." (Anker 2001, p. 25)
Anker repeats this claim elsewhere in the book and rather onomatopoetically in an interview featured within a BBC broadcast (from min. 55:19 on counting down).  

BBC withdrew the video from youtube, but the following links work (still at 16.03.2012): You want to see the second part of the trilogy. Leaving the onomatopoeia out, let's fix Anker's central claim about Tansley in this interview. 
"... creating a network a system within the mind. Now this he would just transfer one-to-one, almost, into his description of the natural environment, in which energy between species and among the species would constitute a system - an ecosystem."
See the news section of his blog also. Paraphrasing Tansley, if some of the following comments are blunt and provocative I am sure Peder Anker will forgive me.
I have once had the same hunch, namely that Tansley transferred a model from psychology to ecology and thus arrived at the ecosystem concept. Alas, I failed to find any evidence for it. Admittedly, Tansley's (1925) textbook on psychology features some figures that are highly intriguing for ecologists, because they depict associative networks of the mind (Tanlsey's figures of mental networks are reprinted in Dagg 2007).   Mental networks - food webs - shouldn't there be a connection?  Don't let your own mind associate this too quickly and without further evidence, because Tansley's writing does not substantiate the idea that he fleshed out his ecosystem concept with a network structure. He neither fleshed it out with an energy flow structure nor with a material cycle structure. Tansley did not flesh his ecosystem concept out at all. He proposed a mere definition much like Haeckel defined ecology without contributing any content: 
"But the more fundamental conception is, as it seems to me, the whole system (in the sense of physics), including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment of the biome–the habitat factors in the widest sense. Though the organisms may claim our primary interest, when we are trying to think fundamentally we cannot separate them from their special environment, with which they form one physical system.    It is the systems so formed which, from the point of view of the ecologist, are the basic units of nature on the face of the earth. Our natural human prejudices force us to consider the organisms (in the sense of the biologist) as the ost important parts of these systems, but certainly the inorganic "factors" are also parts–there could be no systems without them, and there is constant interchange of the most various kinds within each system, not only between the organisms but between the organic and the inorganic. These ecosystems, as we may call them, are of the most various kinds and sizes. They form one category of the multitudinous phsical systems of the universe, which range from the univers as a whole down to the atom.” (Tansley 1935, p. 299)
That's it. A passage aimed at clarifying the boundaries of the ecological unit under study, insisting that inorganic factors are to be taken into that unit. Remembering that the word definition comes from latin and means delineation, this is a pure definition that does not specify the internal structure of the ecosystem except insisting that the border must be drawn to include abiotic factors and animals along with vegetation. As Dagg (2007) pointed out, Tansley may indeed have been primed to look for more inclusive units of research through psychology. There he got used to deal with the mind as though it was an organism knowing quite well that it was only part of a more inclusive one: 
"The New Psychology, then, looks upon the human mind as a highly evolved organism" (Tansley 1925, p. 24)
The reason why psychoanalysts studied the mind on its own was an unbrigeable gap in knowledge of how the mind was causally related to the brain (the mind/body problem troubling philosophy and science ever since Descartes). But that does not mean that Tansley carried his mental networks along into ecology.  If anything, Tansley (1935) discussed his more inclusive ecosystem unit in relation to ecological succession, because the whole controversy with his fellow ecologists was about succession and the question whether it was the development of  a complex organism or an aggregate effect. There's talk about equilibrium in this discussion (Tansley 1935, p. 300 onwards). Firstly, however, there's always talk about equilibria in ecology and, secondly, the whole idea of a vegetational organism was based on the assumption of a climax equilibrium.     The very success of the ecosystem concept, in comparison to other early ecosystemic concepts that drowned because of their connotations, was due to its emptiness rendering it ready to be used by later ecologists. In fact, the ecosystem patterns of material cycles, energy flows, and food webs were all filled in later.  Anker (2001, p. 139ff; 2002) somehow reads the ostensible projection out of a previously unpublished manuscript of Tansley presented before the Magdalen Philosophy Club of Oxford in 1932. Previously unpublished means that Anker laudably prepared this manuscript for publication in 2002.     However, I fail to read a projection out of that paper. In it Tansley proposes what might be called a continuation of the big bang story starting with inorganic matter going through living organisms ending with the human mind. The question he addresses is whether the gaps can be bridged by science, that is, whether science can come up with an account of how life evolved from protoplasm and how mind evolved from mindless organisms. Tanlsey's answer is yes concerning the first gap an no concerning the second. 
"From the standpoint of the human observer, then, the gap between the physiological and the psychical is a gap of a different nature from that between the organic and the inorganic. [...] We cannot hope to bridge the gap between the physiological and the psychical because all our knowledge is founded on the very power we seek to interpret." (Tansley 1932/2002, p. 618).
The mind, he thought, cannot comprehend itself. Moreover he regarded this gap as unbridgeable in principle, whereas the first gap (inorganic -> organic) may only be unbridgeable in practice and be bridged later. That's surprising! The staunch reductionist Tansley admits that the mind/body problem may be too big to reduce mind to brain.  But why, then, should Tansley export psychological concepts into ecology, given that he had no philosophical reason to expect insight from it? This manuscript does not support Anker's claim that he cobbled his mental network into his ecosystem concept. If there is no other source yet unpublished, I shall stay unconvinced.   I agree with Anker (2002, p. 613) that "The paper is Tansley's main contribution to the philosophy of science and the longest explanation to be found of his broad use of the word "system," it encompasses a broad spectrum of natural, epistemological, and moral issues." Anker (2002) also provides the background information that Tansley received an idealist paper from Phillips and sent the manuscript from the Magdalen Philosophy Club in return. This in turn spurred Phillips to write a rejoinder ending in Tansley's seminal paper of 1935, wherein he ended his heuristic support of Clements's organism metaphor for vegetation. This answers Liam Heneghan's question: "What was eating at Sir Arthur G. Tansley?" A prolonged controversy between idealists and realists carried out in the Magdalen Philosophy Club as well as in psychology and ecology. The only thing I cannot see in all this is evidence of an analogous transfer of the network as the internal structure of the mind (not brain) to the network as the internal structure of the ecosystem. As far as I know, Tansley never specified an internal structure of the ecosystem. It is true that later ecologists (e.g., Golley, the Odums) were guided by a machine metaphor. However, the metaphor guiding Clements, Tansley and his colleagues before 1935 was the organims not the machine. Among the guiding metaphors of (micro-)cosm, (super-)organism, and (mega-)machine, Tansley (1935) divorced from a previous marriage of convenience he called "quasi-organism" and did not marry another. About the ecosystem patterns of web, flow, and cycle, however, he had nothing to say. In conclusion, Anker and the broadcast above project a guiding machine metaphor and insights into ecosystem structure from a later period (after the 2nd world war) into Tansley's empty concept rather than proving a projection on the part of Tansley. Summarising my caveats: 
  1. Tansley was a botanist. He did not have the dog-eat-dog experience to suggest the kind of food web described. The pioneer ecologists on food webs were Stephen A. Forbes and Charles Elton (see here). Tansley's reminder that in studying vegetation he and his colleagues must keep in mind that the animal community and abiotic factors also belong to the system under study was theoretical/heuristic. 
  2. The energy perspective suggested stems from a later period of ecosystem research initiated by Lindeman (1942) and the Odum brothers. 
  3. The machine as a guiding metaphor for ecosystems is also from this later period. Tansley and his colleague botanists were guided by an organism metaphor for vegetation until Tansley rejected it in 1935.
  • Anker P (2001) The temporal genetic series as a means of approach to philosophy. Ecosystems 5: 614-624.
  • Anker P (2002) The context of ecosystem theory. Ecosystems 5: 611-613.
  • Dagg JL (2007)  Arthur G. Tansley’s ‘new psychology’ and its relation to ecology. Web Ecology 7: 27-34 []
  • Levy H (1932) The Universe of Science. Watts & Co., London. 
  • Lindeman RL (1942) The trophic dynamic aspect of ecology. Ecology 23: 399-417.
  • Tansley AG (1925) The new Psychology and its Relation to Life. George Allen & Unwin Ltd, London.
  • Tansley AG (1932/2002) The temporal genetic series as a means of approach to philosophy. Ecosystems 5: 614-624. [presented before the Magdalen Philosophy Club of Oxford University on 5 May 1932; prepared for publication by Peder Anker]
  • Tansley AG (1935) The use and abuse of vegetational concepts and terms. Ecology 16: 284-307.


  1. Joe, this is great - I had seen that section of the documentary before, and it had seemed to me that Anker's account was inconsistent with Tansley's 1935 account of the ecosystem. I do need to read his book though but your analysis here is compelling.

  2. Liam, I'm glad you agree with me. I feared it might be seen as outlandish. Apart from this compounding of Tansley's empty concept with the later filling, however, I really liked Anker's book very much.