Terry Hurlbut examines the concept of irreducible complexity:
Irreducible complexity. That phrase gets a lot of attention in the creation-evolution debate, or the accident-design debate. As well it should. Irreducible complexity shows that life did not come about by accident, but by design. Recently the advocates for “intelligent design” claimed vindication. Now it’s time to review the concept.
Irreducible complexity and what it means
Irreducible complexity generally means this: any system must be at least complex enough to function. The question is, how complex must it be? Charles Darwin himself admitted: if anyone could show that a biological system was too complex to come about by accident, his entire theory would fail.
Michael Behe made “irreducible complexity” a household phrase with his book, Darwin’s Black Box. His thesis: at last biochemistry and cell biology had found out what was in the cell and how the cell worked. Behe found that a cell needs a minimal set of subsystems to work. And to get that, everything had to come together at once.