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The Levels of Irreducible Complexity

September 18, 2011

The Levels of Irreducible Complexity

Previously, I have discussed how irreducible complexity (IC) is a real biotic phenomenon, and that the higher the level of IC in a given system, the less likely it is that that system evolved. How does one determine the “level” of IC in a system? I will attempt to answer that question, but keep in mind that this is certainly a disputed topic. Indeed, some intelligent design proponents will argue that there is no such thing as a “level” of IC in a system, and that all IC systems are equal.

What is the advantage of having “levels” of IC in the first place? Well, the higher the level of IC in a biological system, the less likely it is that that system arose through a purely non-teleological process. Thus, biological structures with a fairly high level of IC are indirect indicators of a discontinuity in the biological world, where certain IC systems are discontinuous from the rest of the biological universe. And discontinuity is an indicator of teleology, though certainly not the only one.

Several factors affect the level of IC of a system, and a number of these are described below.

 

Minimum number of components

The minimum number of components a system requires in order for the function of that system to be maintained is one factor that plays a role in determining the level of IC in a given system. In the world of life, this would be done by determining the phylogenetic distribution of the components of the system: if components ABCDE of a given IC system are found in E. coli, and components ABCGF are found in Firmicutes, and components ABCHJ are found in Aquifex, then this would indicate that components ABC are the minimum components needed for that system’s function to be maintained.

Flexibility of the components

The amount of modification a component of an IC system can tolerate, without the loss of the original function of the IC system, is another indicator of the level of IC. The less flexible the component is to modification, the higher the level of IC.

Number of precursor systems

The number of precursor systems that pre-date that IC system may also be used to determine the level of IC of a biological structure. The fewer the number of precursor systems that pre-date the IC system, the higher the level of IC system.

Cascade system or non-cascade system?

If an IC system is a cascade system then it is significantly more likely for that system to have evolved through non-telic mechanisms than it would be if that IC system required that all of its components worked together, at the same time, in order for the function to be maintained. Thus, if an IC system is a cascade system, then it has a low level of IC.

 

In upcoming articles, I will be discussing how the levels of IC can aid us in forming telic predictions about the living world.

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