In 2002, a previously unpublished paper by Arthur G. Tansley has eventually been published in the Journal Ecosystems. Tansley called it "The Temporal Genetic Series as a means of Approach to Philosophy" and presented it before the Magdalen Philosophy Club of Oxford University on 5 May 1932. Peder Anker eventually discovered it in some archive and prepared it for publication. I wanted to add a link to the full text, but Springer put it behind a paywall - gasp. So here's a digest instead.
By temporal genetic series Tansley simply meant the evolutionary transitions:
inorganic matter → living organisms
He was particularly interested in the question whether the gaps between (1.) the not-living and the living and between (2.) the living and mind were bridgeable in terms of chemistry and physics. In philosophical discourses this is often called reducibility.
Tansley concludes that the 1. gap is not unbridgeable in principle, though it may well be in practice:
"I need not deal with the steady advance in our knowledge of the physico-chemical mechanism of life. That knowledge is certainly very far from complete. It may indeed never bee complete, but I see no reason to suppose that there are any phenomena of life (leaving "mind" for the moment out of consideration) that are not theoretically capable of "explanation" in terms of chemistry and physics." (Tansley 2002, p. 617)
When he reaches the 2. gap, however, he concluded that it is unbridgeable in principle. We cannot understand mind, because mind would have to understand itself. This is, he thinks, as if we had to study the structure and functioning of a microscope with the microscope, "permanently glued to our eyes. [...] 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 2002, p. 618)
At the end of this paper, Tansley touches on the emergence of values from mind as a third gap, which he suspects to be irreducible too, and summarizes:
"The first gap, between the inorganic and the organic, I have attributed to a lack of knowledge, an ignorance that we may possibly, perhaps probably, never surmount, but that I do not believe is theoretically unbridgeable by human knowledge. The organism I have thus considered is a physico-chemical system, so highly specific that we cannot help calling it a new phenomenon.
The second gap, between the physiological and the psychical, I attribute to the fact that psychical awareness is the foundation of all human knowledge and the instrument through which we contemplate the external world and also our own minds. For that reason, it is impossible to understand awareness in terms of anything else, though its antecedents are clearly physiological perceptions that we can explain theoretically in terms of chemistry and physics." (Tansley 2002, p. 624)
In conclusion, Tansley's heuristics for studying ecology and psychology are contrary. In ecology, he suggested the ecosystem because it already bridges
the gap between organic and anorganic factors. In psychology, however, he always defended the psychoanalytic approach of taking the mind as something that cannot be explained in terms of physiology.
Tansley, AG ( 2002) "The Temporal Genetic Series As a Means of Approach to Philosophy." Ecosystems 5: 614-624.