At The Panda's Thumb, Nick Matzke has a post about abiogenesis (the origin of life from non-life) and evolution. He, PZ, and others argue that abiogenesis is part of evolutionary biology and that it is a cop-out to deflect challenges about it from anti-evolutionists. Allow me a brief summary of my interpretation.

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Question: Do we need evolutionary biology to understand the origin of life?

Answer: Very probably. Early replicators, once they arise, would undergo evolution. Mutation, natural selection, etc., would have been important before cellular life as we understand it appeared. However, there are components to the issue that predate the occurrence of natural selection, which are more properly understood in terms of organic chemistry than biology. The line is not sharp, though, so keeping evolution out of abiogenesis research is unwise.

Evidence: Whether "cells" (membranes with stuff inside) or replicator molecules (e.g., RNA) appeared first, if there was heritable variation and reproduction and survival that differed among them, then selection would have happened.

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Question: Do we need to understand how life arose to understand the subsequent evolution of cellular life?

Answer: No.

Evidence: We have been studying evolution seriously for 150 years and understand quite a bit about how it happens, yet we don't know how life arose.

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So, Nick and others are correct that we should not say that abiogenesis is independent of evolution. However, if they are implying that abiogenesis is part of — more importantly, a crucial part of — evolutionary theory, then I do not agree. The influence is one-way, and this is the opposite of the way anti-evolutionists perceive it. They argue that if we do not know how life started, then evolution is false. In actuality, knowing how life started has nothing to do with studying how life has evolved since the first complex cells appeared. However, understanding how complex cellular life evolves probably tells us something about how life arose because the same processes are relevant whenever there are variable replicating entities.

In my opinion, it remains a valid and useful argument to point out that uncertainty regarding the origin of life is irrelevant to the factual standing of evolution over the past 3.8 billion years.