All risk comes from uncertainty, reducible, and irreducible.
Making any credible decision in the presence of uncertainty requires making an estimate of the probability of success of that decision on the project
Risk Management is Project Management for Adults - Tim Lister
To NOT estimate the probability of success in the presence of uncertainty, a Not To Exceed Budget, a Deadline, or a set of Mandatory Features of to NOT behave like an adult while spending other people's money
