Irreducible complexity is fallacious. The argument of irreducibility must assume that evolution is false, and the conclusion it reaches is that evolution is false. You can always conclude your assumptions.
They say, “a cell is too complex to be the product of evolution. If it were, there would be simpler cells in existence.” There would not be. The simpler cells have DIED due to the fact that they did not become more complex. That’s what natural selection is.
It is mutation that has fostered evolution in the exact same way that a mutation has made me terminally ill. How’s that for some unintelligent design? But guess what? Natural selection works. I will not be having children. This genetic mutation will terminate in a leaf of my family tree. As all disadvantageous mutations eventually do.