The world in which we live can be understood as a result of muddle and accident; but if it is the outcome of deliberate purpose, the purpose must have been that of a fiend. For my part, I find accident a less painful and more plausible hypothesis.

Logic must no more admit a unicorn than zoology can.

Zeno was concerned with three problems... These are the problem of the infinitesimal, the infinite, and continuity.

What the world needs is not dogma but an attitude of scientific inquiry.

On the one hand, philosophy is to keep us thinking about things that we may come to know, and on the other hand to keep us modestly aware of how much that seems like knowledge isn't knowledge

There is no logical impossibility in the hypothesis that the world sprang into being five minutes ago, exactly as it then was, with a population that "remembered" a wholly unreal past. There is no logically necessary connection between events at different times; therefore nothing that is happening now or will happen in the future can disprove the hypothesis that the world began five minutes ago.

No matter how eloquently a dog may bark, he cannot tell you that his parents were poor, but honest.