He did not think that all knowledge is precise. There is such a thing, particularly in the social sciences, as complex knowledge that is dependent on indeterminate variables and which thus is not susceptible to exact prediction. He sometimes referred to the lesser prediction to which knowledge such as the effects of societal rules is susceptible as pattern prediction. Where prediction is limited, control is limited. Correct prediction precedes control. The greater the accuracy of prediction, the greater the control that is capable of being exercised.

Hayek's Journey: The Mind of Friedrich Hayek (2003) - Ch. 11 : The Constitution of Liberty