Does Evolution have a Purpose?

I have already suggested that although design is not involved in evolution, this does not rule out purpose. 

1. I understand by design a detailed plan, drawn up before the proposed work is done.  God the designer is equivalent to the traditional Calvinist God, who created everything at the beginning, with no room for error.  Is it necessarily the case that God's purpose is best served by such an inflexible approach to creation?  Theologically it opens up several problems, such as why does a good (and absolute) creator allow suffering?  The answer must boil down to: it depends upon what God is trying to achieve.