The notion of irreducible complexity in relation to biological systems was first considered in detail by Michael Behe in "Darwin's Blackbox" in the 1990-s. As an example he looked at autocatalytic cycles of blood clotting. The main counter-argument against his anecdotal claims is the ability of living systems to switch, or co-opt, between functions. His famous mousetrap, an epitome of functional systems, could have been used for a different purpose initially. It is quite likely that for concrete cases it is possible to provably demonstrate co-optational chains. Nonetheless, the principal problem of irreducible complexity cannot be explained away like that.
The problem of irreducible complexity as such, not necessarily in biological contexts, has two aspects.
- Firstly, this problem concerns the existence of goals or goal states. While living matter is inherently teleological, goal-oriented, non-living matter isn't. Every co-optational chain must have had a first element.
- Secondly, irreducible complexity is an intrinsic property of organised systems. According to William Ashby, organisation is, in a sense, irreducibility. Protein life is irreducible to physics or chemistry. And this is an empirical fact, whatever the implications. The organisational hierarchy of this world entails gaps of irreducibility. Consciousness and libertarian free will are irreducible to physics as well. There is a similar phenomenon in complexity theory where, apparently, there are no polynomial reductions of decision problems in the class NP to those in the class P (the famous NP =/= P alleged inequation). ID is inherently intertwined with libertarian free will. Such things as consciousness, self-awareness, wisdom, or even protein life cannot spontaneously emerge from chaos.
- Ashby, W. R. (1962): Principles of the self-organizing system.Principles of Self-Organization: Transactions of the University of Illinois Symposium, H. Von Foerster and G. W. Zopf, Jr. (eds.), Pergamon Press: London, UK, pp. 255-278.
- Michael Behe: Darwin's Blackbox.