Downward Causation - Some Second Thoughts
In the years 2007-2010 I have revised my opinion on the use of a prominent term that I previously adopted and refined. I would first like to sketch the origin and usage of that term, note my own adoption and refinement of it, explain why I have changed my mind, and indicate what term I am going to use instead. The meaning of what I previously described as "reconstitutive downward causation" is retained, but I shall henceforth describe it differently.
The Origin and Usage of "Downward Causation"
The term "downward causation" originates in psychology in the work of the Nobel psychobiologist Roger Sperry (1964, 1969). It was elaborated further by Sperry (1976, 1991), Karl Popper and John Eccles (1977), James Murphy (1994), Peter Andersen et al. (2000) and others.
In its literature, the notion of downward causation has weaker and stronger forms. In a weaker formulation, Donald Campbell (1974) sees it in terms of evolutionary laws acting on populations. He argued that all processes at the lower levels of an ontological hierarchy are restrained by and act in conformity to the laws of the higher levels. In other words, if there are systemic properties and tendencies then individual components of the system act in conformity with them. For example, a population of individual organisms is constrained by processes of natural selection.
By contrast, Roger Sperry (1991, pp. 230–231) suggests a stronger interpretation of downward causation. He recognizes, for example, that "higher cultural and other acquired values have power to downwardly control the more immediate, inherent humanitarian traits."
At first sight this may seem to go against the stricture of Mario Bunge (1979, p. 39) that: "There is no action of the whole on its parts; rather, there are actions of some components upon others." But if structures can enable or constrain individual behaviours, then interactions with other individuals will partly reflect structural properties.
Claus Emmeche et al. (2000) identify three versions of downward causation: strong, medium and weak. By "strong" downward causation they mean some mechanism by which entities or processes at a higher level bring about "a direct change in the laws of the lower level (or at least a change in lawful regularities at this level) effected from above" (p. 19). They reject this possibility: although higher level entities can constrain processes at a lower level, the laws of nature at the lower level cannot be overturned. Chemistry, for example, cannot defy the laws of physics, and biology has to be consistent with both physics and chemistry. For Emmeche et al. the only viable cases of downward causation are "medium and "weak." Medium downward causation means that "higher level entities are constraining conditions for the emergent activity of lower levels" (p. 25).
"Reconstitutive Downward Causation"
In various works I proposed a "reconstitutive" version of downward causation (Hodgson 2002, 2003, 2006a, 2006b, Hodgson and Knudsen 2004) that is consistent with the "medium" conditions of viability advanced by Emmeche et al. (2000). I ruled out the possibility that reconstitutive downward causation means that social laws or forces can overturn the principles governing the operation of human mental and physical activity at the level of the individual.
Sperry (1991, p. 230) himself insisted on a similar condition: "the higher-level phenomena in exerting downward control do not disrupt or intervene in the causal relations of the downward-level component activity." I termed this "Sperry’s Rule.". It ensures that emergence, although it is associated with emergent causal powers at a higher level, does not generate multiple types or forms of causality at any single level. Any emergent causes at higher levels exist by virtue of lower-level causal processes.
Adherence to Sperry’s Rule excludes any version of methodological collectivism or holism where an attempt is made to explain individual dispositions or behaviour entirely in terms of institutions or other system-level characteristics. Instead, Sperry’s Rule obliges us to explain particular human behaviour in terms of causal processes operating at the individual level, such as individual aspirations, dispositions or constraints. Where higher-level factors enter, it is in the more general explanation of the system-wide processes giving rise to those aspirations, dispositions or constraints.
In my works of 2002-2006 cited above, I made it clear that at the level of the human agent, there are no magical "cultural" or "economic" forces controlling individuals, other than those affecting the dispositions, thoughts and actions of individual human actors. People do not develop new preferences, wants or purposes because mysterious "social forces" control them. What have to be examined, I argued, are the social and psychological mechanisms and constraints leading to such changes of preference, disposition or mentality.
Critique and an Alternative
In 2007 I had discussions with my philosopher friend Achim Stephan and he questioned the use of the word "causation" in this context. Some time later I came acroos two critiques that also budged my thinking.
Menno Hulswit, (2006) argues that downward causation is about explanation and determination, not causation. Hence the term is "badly chosen." The last bit is probably right, but something more than explanation is involved. The whole literature on this topic is about ontological relations between levels. These ontological issues are addressed in more detail by Carl Craver and William Bechtel (2007). They write:
"The idea of causation would have to stretch to the breaking point to accommodate interlevel causes. The notion of mechanistically mediated effect is preferable because it can do all of the required work without appealing to mysterious interlevel causes. ... Mechanistically mediated effects are hybrids of constitutive and causal relations in a mechanism, where the constitutive relations are interlevel, and the causal relations are exclusively intralevel" (p. 573).
Reviewing the work of Sperry and others, and my own previous use of it, the idea of "interlevel causes," i.e. direct causal relations between one level and another, had already been ruled out. The examples I had given the social sphere, relied on institutional incentives or constraints engendering changed habits and beliefs in individuals. As institutions channel our behaviour, we get used to the pattern, and may even come to prefer it. "Custom reconciles us to everything" as Edmund Burke put it in 1757. I still uphold these arguments and and see them as a major reason why preferences should not generally be taken as given.
Henceforth I propose to use the term reconstitutive downward effects. By definition, such effects exist when a system containing lower-level elements, creates or reiterates conditions that can be related to changes in the character of the lower-level elements.
I have recently discussed these issues with my co-author Thorbjørn Knudsen. We agree that "causation" in "reconstitutive downward causation" is misleading.
1 March 2011
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