… is from page 197 of the 1993 Liberty Fund collection of H.B. Acton’s insightful writings, The Morals of Markets and Related Essays :
Hayek holds that the fact of necessary or inevitable ignorance (he uses both adjectives) provides the chief reason for allowing the fullest possible scope to individual freedom. It is because of this ignorance that it is better to allow society to develop by spontaneous adjustment than to control it all by some central agency. Those who recognize the inevitability of ignorance will not pin their hopes on plans for society as a whole, but will want there to be scope for everyone to gain from the impersonal beneficence of transactions that are imperfectly understood.