Risk with unknown probability distribution of the outcomes From Wikipedia:
&quot;Risk aversion comes from a situation where a probability can be assigned to each possible outcome of a situation and it is defined by the preference between a risky alternative and its expected value.&quot;
&quot;Ambiguity aversion ... is defined through the preference between risky and ambiguous alternatives, after controlling for preferences over risk.&quot;
What is the preference between an ambiguous alternative and a certain outcome referred to? For example, the choice between a certain reward and an unknown probability to win a larger reward.
I think it is not risk aversion, because an alternative's probability distribution of the outcomes is unknown, and not risk ambiguity because one alternative does not entail a risk.
A sure outcome is just a special case of a risky alternative with a degenerate probability distribution.
Under a set of appropriate conditions, the choice of a sure outcome over an ambiguous alternative can be attributed ambiguity aversion. But since different authors define ambiguity aversion somewhat differently, the &quot;appropriate conditions&quot; also differ. On the other hand, choosing a sure \$100 over an uncertain distribution over \$1 and \$2 can hardly be called ambiguity averse.