The Application of Reductive Methods to Study Complex- and Complex-Adaptive Systems in Ecology

Kees Hulsman, Gurudeo Anand Tularam, Graham Willett


In this paper, we focus on how to use reduction to understand natural phenomena better. Natural phenomena occur in physical and living systems. Hierarchical physical systems are best represented as Complex Systems (CS), and living ones as Complex Adaptive Systems (CAS). CS and CAS differ in one important way. CAS can adapt by learning or evolving, whereas CS cannot. Any CAS is governed by a mix of level-invariant and level-specific rules, whereas CS has only level-invariant ones. Level-specific rules give rise to adaptive behaviour and affect the utility of reduction. There are three basic types of reduction: ontological, epistemic and methodological. Although biology cannot be reduced to physics and chemistry, all three reductive types have an important role to play in studying biological systems. Ontological reduction can help identify structural components at each level of a system, but not necessarily their functional relationships. This limitation arises when level-specific-rules and the information they generate are lost in the reductive process. Epistemic reduction meets the same limitation. The problem with methodological reduction is not knowing beforehand how many mechanisms produce the same outcome. To avoid this limitation, one must remain cognisant of level-specific rules and the information they supply. CAS should be studied by combining reduction and integration. First, use ontological reduction to identify the structural components at each level, second, use epistemic and/or methodological reduction, and third, use integration iteratively to reveal how components interact. This iterative top-down and bottom-up approach keeps the phenomenon in the context in which it occurs.


Ecology; Emergent Properties; Epistemic Reduction; Level-Specific Rules; Level-Invariant Rules; Life Sciences; Methodological Reduction; Ontological Reduction; Physical Sciences

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