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.

The overwhelming majority of theories are rejected because they contain bad explanations, not because they fail experimental tests.

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.

Time travel may be achieved one day, or it may not. But if it is, it should not require any fundamental change in world-view, at least for those who broadly share the world view I am presenting in this book.

Despite the unrivaled empirical success of quantum theory, the very suggestion that it may be literally true as a description of nature is still greeted with cynicism, incomprehension, and even anger.

The theory that the biosphere was created without evolution, a few thousand years ago, is ruled out by overwhelming scientific evidence. To claim that there are 'alternative (always better) Biblical explanations of the same data', which make creationism a reasonable alternative to our best theories of biology and physics, is appalling intellectual dishonesty.

Science is objective. And in my view we cannot take any experimental results seriously except in the light of good explanations of them.