Since the time of the Greeks, democracy has been understood to have a spatial dimension and so, by extension, an element of scale. Plato measured the polis, the unit of democratic citizenship, at five hundred citizens, an extremely tractable size for a community that seeks to express itself through direct engagement.
The wonderful thing about living in a world of our own creation is that we get to choose what kind of world it's going to be—at least in principle. But the promise is meaningful only if a broad enough "we" can be engaged in the process. At present, mechanisms and democratic institutions for making collective decisions about the deployment of technology are hopelessly cumbersome. How can anyone make a sensible choice without being able to weigh one alternative against another?
We might be closer than we think to cures for depression, hypertension, and yes, even obesity.
The answer to scurvy was just one thing, plus a few wrinkles — mostly “not all citrus has the antiscorbutic property” and “most animals can’t get scurvy”. This was only difficult because people weren’t prepared to deal with basic wrinkles, but we can do better by learning from their mistakes.
This means don’t give up easily. It suggests that there is lots of low-hanging fruit, because even simple explanations are easily missed.
Lots of theories have been tried, and lots of them have been given up because of something that looks like contradictory evidence. But the evidence might not actually be a contradiction — the real explanation might just be slightly more complicated than people realized. Go back and revisit scientific near-misses, maybe there’s a wrinkle they didn’t know how to iron out.