Sunday, January 20, 2008

Understanding Downward Causation

This article titled Excursus: Defining Downward Causation, helps to illustrate the meaning of top down or downward causation. The article uses the jaw anatomy of a worker termite or ant to demonstrate the concept of downward causation.

A design construction featuring hinge surfaces and muscle attachments allow for the application of maximum force at a distance from the hinge for a biting or grasping function. Underlying laws of physics are utilized by gross anatomical structures, composed of multiple parts, to accomplish an objective that is beneficial to the whole organism.

Contrast the foregoing with a bottom up effect which can be illustrated by the binding of ATP to a transmembrane protein to facilitate the transport of molecules across cell membranes. The molecular binding initiates a larger biological operation.

The following quoted paragraph from the article (in blue) is instructive:

Downward causation, then, is a matter of the laws of the higher-level selective system determining in part the distribution of lower-level events and substances. "Description of an intermediate-level phenomenon," he says, "is not completed by describing its possibility and implementation in lower-level terms. Its presence, prevalence or distribution (all needed for a complete explanation of biological phenomena) will often require reference to laws at a higher level of organisation as well"

In the case of the termite or ant jaws large biological structures, exploiting higher level physics concepts (Archimedes' levers), control lower level biological functions. Biological explanations for what occurs invoke references to actions controlled by higher level biological organization.

One final point, to be elaborated on in future blogs, concerns the original source of biological organisms. Mainstream biology utilizes bottoms up causal scenarios to explain life from abiogenesis through evolution. Intelligent design is a bit more flexible. Intelligent design can be evidenced in either direction. More on that to come.



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