“The scepticism that I advocate amounts only to this:
1. that when the experts are agreed, the opposite opinion cannot be held to be certain;
2. that when they are not agreed, no opinion can be regarded as certain by a non-expert; and
3. that when they all hold that no sufficient grounds for a positive opinion exist, the ordinary man would do well to suspend his judgment.”
-- Bertrand Russell, from “On the Value of Scepticism” (1928)
Source: panarchy.org