Results rarely specify their causes unambiguously. If we have no direct evidence of fossils or human chronicles, if we are forced to infer a process only from its modern results, then we are usually stymied or reduced to speculation about probabilities. For many roads lead to almost any Rome.

Objectivity cannot be equated with mental blankness; rather, objectivity resides in recognizing your preferences and then subjecting them to especially harsh scrutiny - and also in a willingness to revise or abandon your theories when the tests fail (as they usually do).

But our ways of learning about the world are strongly influenced by the social preconceptions and biased modes of thinking that each scientist must apply to any problem. The stereotype of a fully rational and objective scientific method, with individual scientists as logical (and interchangeable) robots, is self-serving mythology.

Life began three and a half billion years ago, necessarily about as simple as it could be, because life arose spontaneously from the organic compounds in the primeval oceans.

Evolution has encountered no intellectual trouble; no new arguments have been offered. Creationism is a home-grown phenomenon of American sociocultural history-a splinter movement ... who believe that every word in the Bible must be literally true, whatever such a claim might mean.

Honorable errors do not count as failures in science, but as seeds for progress in the quintessential activity of correction.

The world is full of signals that we don't perceive.