Uncertainty is intrinsic and pervasive in understanding economic behaviour. Knight (1921) distinguished quantifiable uncertainty as risk, in the sense of being amenable to a statistical analysis using historical or experimental data, and fundamental uncertainty, that is intrinsic and unknowable. The recognition of fundamental uncertainty is a critical feature of Keynesian economics, which distinguishes it from neoclassical economics, which assumes that agents can characterise uncertain outcomes by well-defined probability distributions.
Baddeley (2011) provides a helpful review
Baddeley, M. (2011) ‘Information Security: Lessons from Behavioural Economics’, available as a .pdf
Fontana G. 2009. Money, Uncertainty and Time. Psychology Press
Knight, F. H. (1921) Risk, Uncertainty, and Profit, Boston, MA