this is from wikipedia
irreducible complexity is the argument that certain biological systems with multiple interacting parts would not function if one of the parts were removed, so supposedly could not have evolved by successive small modifications from earlier less complex systems through natural selection, which would need all intermediate precursor systems to have been fully functional. this negative argument is then complemented by the claim that the only alternative explanation is a "purposeful arrangement of parts" inferring design by an intelligent agent. Irreducible complexity has become central to the creationist concept of intelligent design, but the concept of irreducible complexity has been rejected by the scientific community at large, which regards intelligent design as pseudoscience. Irreducible complexity and specified complexity are the two main arguments used by intelligent-design proponents to support their version of the theological argument from design.
