UNCERTAINTY AND THE DIFFICULTY OF THINKING THROUGH DISJUNCTIONS

This paper considers the relationship between decision under uncertain ty and thinking through disjunctions. Decision situations that lead to violations of Savage's sure-thing principle are examined, and a varie ty of simple reasoning problems that often generate confusion and erro r are reviewed. The common difficulty is attributed to people's reluct ance to think through disjunctions. Instead of hypothetically travelin g through the branches of a decision tree, it is suggested, people sus pend judgement and remain at the node. This interpretation is applied to instances of decision making, information search, deductive and ind uctive reasoning, probabilistic judgement, games, puzzles and paradoxe s. Some implications of the reluctance to think through disjunctions, as well as potential corrective procedures, are discussed.