“Absence of proof is not proof of absence.”

“Do you know what we call opinion in the absence of evidence? We call it prejudice.”

“The fact that the biosphere responds unpredictably to our actions is not an argument for inaction. It is, however, a powerful argument for caution, and for adopting a tentative attitude toward all we believe, and all we do. Unfortunately, our species has demonstrated a striking lack of caution in the past. It is hard to imagine that we will behave differently in the future.We think we know what we are doing. We have always thought so. We never seem to acknowledge that we have been wrong in the past, and so might be wrong in the future. Instead, each generation writes off earlier errors as the result of bad thinking by less able minds--and then confidently embarks on fresh errors of its own.We are one of only three species on our planet that can claim to be self-aware, yet self-delusion may be a more significant characteristic of our kind.”

“Like everything else I'd seen at Xymos, it was jerry-built, half-baked, concocted in a hurry to solve present problems and never a thought to the future.”

“But it was one thing to release a population of virtual agents inside a computer's memory to solve a problem. It was another thing to set real agents free in the real world.”

“The greatest challenge facing mankind is the challenge of distinguishing reality from fantasy, truth from propaganda. Perceiving the truth has always been a challenge to mankind, but in the information age (or as I think of it, the disinformation age) it takes on a special urgency and importance.”

“Each person bears a fear which is special to him. One man fears a close space and another man fears drowning; each laughs at the other and calls him stupid. Thus fear is only a preference, to be counted the same as the preference for one woman or another, or mutton for pig, or cabbage for onion.”