The true idea that all problems are solvable; the attitude that it is the duty of people to seek solutions and never declare that a problem is unsolvable.
Rejection of optimism causes Stasis. Optimism is not naive — it does not say problems will be solved, only that they can be. It follows from the nature of Knowledge: since knowledge grows through Conjecture and Criticism, and there is no known limit to this process, every problem is in principle solvable.