Three Phases of Tragedy

Pre-tragic

Naive optimism (belief).

Hasn't encountered the depth and complexity of the problem space (or isn't even aware of the larger problem space with which this optimism is embedded).
The life will find a way narrative: "There have always been problems and humanity has, and will continue to, rise to the challenge."
The better angels narrative (Pinker, Rosling, Gates, etc.): "Things are, on the whole, getting better."

Cynicism and nihilism.

Once you begin to explore the depth and complexity of the problem space, the solutions appear to be impossible. Any one solution seems to make other problems worse (or just shifts the problem elsewhere).
Can lead to an even deeper realization that many of the complicated systems we rely on for managing the complex systems we care about most are self-terminating.
Leads to cynicism: doubt in the human capacity to make effective, moral, and ethical decisions, and eventually, nihilism: the feeling that there is nothing humanity can do and there is no inherent goodness, badness, or meaning in anything anyway.
Although this cynicism and nihilism is a wiser stance than naive optimism, it is like moving from slavery to the "freedom" of wandering in the desert.

Mature optimism (faith).

Realization that there is a false certainty in both the pre-tragic view (naive optimism) and the tragic view (cynicism/nihilism).
An appreciation of, and faith in, the unknown-unknowns (where possible solutions reside).
Where naive optimism says, "We already know it'll be fine, trust me!", mature optimism says, "We don't know exactly how things might get better, but we stay open and engaged because real possibilities often lie beyond what we currently see."
It's a different kind of "optimism" precisely because it isn't rooted in denial or unexamined assumptions, but in a willingness to keep exploring, collaborating, and learning in the face of daunting complexity.