(1) Optimism. The world has been getting better and all present evils can eventually be cured by developing the specific know-how (think Apollo programme)
(2) Eucatastrophe. The world has been getting steadily worse yet looming evil may be defeated by an unexpected turn of events among a few good people (think small fellowship of hobbits)
The first says that if we apply creativity and work energetically at solving problems in a scientific manner then we can solve them. No guarantees but also nothing in the laws of physics to prevent it. It sounds reasonable but in practice the argument seems to persuade very few, least of all in Hollywood where science fiction has all but given up on spaceships and the future. As Douglas Adams pointed out the stories are mostly set in LA about 5 years from now and it's raining.
The second is almost the opposite. It says that if a few unimportant but good people get involved, things may unpredictably and dramatically improve, perhaps by the intervention of grace or Providence. It sounds supernatural. Hope was indeed one of St Paul's big three ('Faith, Hope, and Love'). Yet consider how many scientific discoveries and inventions occurred purely by accident. How evolution succeeded in making ears out of jaw bones. Etc.
Historically I've sided with (1) and I've always wanted it to be true however however many times it is pointed out by the likes of Steven Pinker with graphs and statistics that conditions have improved through most of history, the pessimists still prevail in public news and debates. They get more headlines and seem more serious than their naive opponents.
Why do pessimists carry the day and with such preternatural authority? The very fact that they do hints that they're unwittingly cashing in on the fact that (2) may be correct or at least the predominating factor.
That is, most good things happen by accident, but they do require a few good people to show up.