Perfection
The Great Head.
I'm not unsympathetic to that view. One might say that would have to imply some sort of intelligent creator to give something purpose.Disagree compleately. Natural processes do not have a purpose. Life reproduces because that is the nature of life, not because life is meant to reproduce. There is no intent behind nature.
Some things to consider:
An interesting question would be to ask about bird nests, or ant hills, do they have purpose?
If we accept naturalism me building a doghouse is a natural process. And yet we can talk about the purpose of said doghouse. Clearly there has to be some way for natural processes to produce purposeful objects. What is it? Perhaps evolution can create purpose.
We should note that it seems very much that organs are treated as objects with purposes. What are our eyes for? For seeing! When a kidney no longer filters blood it has failed. Why has it failed? Maybe because it doesn't serve its purpose anymore. It's failure to filter is in the same sense that a failed air filter doesn't filter air anymore. It's extremely common to treat organisms and their parts as purposeful objects. Perhaps that's not a misguided intuition, a holdover from a view of God as an architect, but a recognition that somehow these objects are endowed with purpose, just through means other then a great intelligence.
Anyways, I don't have to much an ideological axe to grind here, maybe we need to be less liberal in our use of "purpose", but I don't think it's unwarranted to use a looser definition.