We can see that the selecting and controlling power of the higher level on the lower level is the main form of downward causation. Gene mutation is the random variation of the lower level, while the struggle for survival and natural selection are the laws at the higher level which affect, determine and select the variation of the lower level system (gene) to determine its survival, spread and distribution.
Downward causation is also apparent in social life.
What Kim presupposes when he makes use of his MP model to eliminate downward causation is that any emergent property M or [M.sup.*] 'is totally dependent on' (Kim, 1999, p.
Another reason why many philosophers cannot accept downward causation is that they do not know what is the owner or carrier of downward causation.
For example, carnivorous animals, herbivorous animals and omnivorous animals have the causation of food chain between them.
Downward causation of a society to individuals cannot be neglected.
In order to get a relatively comprehensive and complete extraction of causation factors and their relationships to construct this railway accident causation network, we can employ some classification approach for specific accidents.
Evidently, the above classification approach covers causation factors with respect to human, equipment, environment, and organizational management, which form a complex system.
In this regard, the failure cascading scheme might be applicable to characterize the evolution process on our proposed accident causation network.
The cascading scheme for accident analysis based on the proposed accident causation network is elaborated as follows.
Therefore, this quantity can, to some extent, indicate how badly the underlying accident causation network is damaged at any time t.