The whole [scientific] process resembles biological evolution. A problem is like an ecological niche, and a theory is like a gene or a species which is being tested for viability in that niche.

Base metals can be transmuted into gold by stars, and by intelligent beings who understand the processes that power stars, but by nothing else in the universe.

The truly privileged theories are not the ones referring to any particular scale of size or complexity, nor the ones situated at any particular level of the predictive hierarchy - but the ones that contain the deepest explanations.

Like every other destruction of optimism, whether in a whole civilisation or in a single individual, these must have been unspeakable catastrophes for those who had dared to expect progress. But we should feel more than sympathy for those people. We should take it personally. For if any of those earlier experiments in optimism had succeeded, our species would be exploring the stars by now, and you and I would be immortal.

Where we have good, testable explanations, they then have to be tested, and we drop the ones that fail the tests.

I don't think it would be a good idea for scientists to have more political power. Scientists as a group are more inclined to try to derive an ought from an is, than the population at large.

Feeling insignificant because the universe is large has exactly the same logic as feeling inadequate for not being a cow.