We conduct a series of experiments and document a robust behavioral pattern whereby people behave more morally in uncertain environments than degenerate deterministic ones. We show that this pattern is weakened when the moral implication of behavior is diminished or when uncertainty pertains to others rather than oneself. These findings are incompatible with standard models that respect dominance. We propose a mechanism based on the anxiety aspect of uncertain environments whereby people act morally as if their moral behavior can help deliver a better outcome. We further delve into the complexity aspect of uncertainty to arrive at a more comprehensive understanding of these findings.

We extend Ellsberg's two-urn paradox and propose three symmetric forms of partial ambiguity by limiting the possible compositions in a deck of 100 red and black cards in three ways. Interval ambiguity involves a symmetric range of 50 − n to 50 + n red cards. Complementarily, disjoint ambiguity arises from two nonintersecting intervals of 0 to n and 100 − n to 100 red cards. Two-point ambiguity involves n or 100 − n red cards. We investigate experimentally attitudes towards partial ambiguity and the corresponding compound lotteries in which the possible compositions are drawn with equal objective probabilities. This yields three key findings: distinct attitudes towards the three forms of partial ambiguity, significant association across attitudes towards partial ambiguity and compound risk, and source preference between two-point ambiguity and two-point compound risk. Our findings help discriminate among models of ambiguity in the literature.