“For every expert there is an equal and opposite expert.”

Illustrated London News (6 April 1918)

Forward to The Power of Negative Thinking (1955)

As quoted in Words from the Wise : Over 6,000 of the Smartest Things Ever Said (2007) by Rosemarie Jarski, p. 170

Variant translations:
Trust one who has gone through it.
Believe one who has had experience.
Source: Aeneid (29–19 BC), Book XI, Line 283; cf. "experto crede".

Krait musing about fingerprints
Source: The Good Guy (2007), Chapter 21, p. 147

Experts
Grooks

Source: 1960s - 1970s, The Systems Approach (1968), p. 232

IETF mailing list archive http://www.ietf.org/mail-archive/web/ietf/current/msg30614.html

One Human Minute (1986)
Context: The book does not contain “everything about the human being,” because that is impossible. The largest libraries in the world do not contain “everything.” The quantity of anthropological data discovered by scientists now exceeds any individual’s ability to assimilate it. The division of labor, including intellectual labor, begun thirty thousand years ago in the Paleolithic, has become an irreversible phenomenon, and there is nothing that can be done about it. Like it or not, we have placed our destiny in the hands of the experts. A politician is, after all, a kind of expert, if self-styled. Even the fact that competent experts must serve under politicians of mediocre intelligence and little foresight is a problem that we are stuck with, because the experts themselves cannot agree on any major world issue. A logocracy of quarreling experts might be no better than the rule of the mediocrities to which we are subject. The declining intellectual quality of political leadership is the result of the growing complexity of the world. Since no one, be he endowed with the highest wisdom, can grasp it in its entirety, it is those who are least bothered by this who strive for power.