The basic argument of anti-evolutionism (Intelligent Design, ID) is that chance processes cannot account for the complexity that we see in living things. The probabilities are simply vanishingly small.
That may be true, but I'm nervous about that kind of argument. The reason is that I'm not sure we properly understand complexity. There are examples of complex systems that behave in apparently extremely improbable ways, if we calculate the probabilities in a straightforward manner. Complex systems are well-nigh impossible to model, so I'm very uneasy about saying, "The probability that a complex system will do X is 0.0000000000000001."