In Learned Optimism, Martin Seligman makes a good case for the many benefits of optimism. So, he asks, what is pessimism for? Why did it get selected for in evolution?
The answer is that pessimists are more accurate about what was and is than optimists are.
In any organization, Seligman argues, you need the optimists to pursue a vision of the future in the face of adversity. And you need some pessimistic bean counters to keep accurate tabs on what resources you actually have and what actions are actually happening now.
I like this balance, even dialectic, of complementary types.
As I argued yesterday, though, I think Seligman is wrong about what optimism is. He conflates optimism and cheerfulness. He sees optimism as the ability to persist in doing in the face of obstacles. He does not have a place for cheerful realism, the ability to accurately see the good and bad in the world, and remain cheerful. His account of optimism tends to reduce virtues to psychological traits that help us achieve the end of getting what we seek. He does not really have a place for virtues as habits of action that let us live in a good way, whether that achieves the ends we seek or not.