  Mutually exclusive decisions have been studied for decades. Many well-known
decision theories have been defined to help people either to make rational
decisions or to interpret people's behaviors, such as expected utility theory,
regret theory, prospect theory, and so on. The paper argues that none of these
decision theories are designed to provide practical, normative and quantitative
approaches for multiple mutually exclusive decisions. Different decision-makers
should naturally make different choices for the same decision question, as they
have different understandings and feelings on the same possible outcomes.The
author tries to capture the different understandings and feelings from
different decision-makers, and model them into a quantitative decision
evaluation process, which everyone could benefit from. The basic elements in
classic expected utility theory are kept in the new decision theory, but the
influences from mutually exclusive decisions will also be modeled into the
evaluation process. This may sound like regret theory, but the new approach is
designed to fit multiple mutually exclusive decision scenarios, and it does not
require a definition of probability weighting function. The new theory is
designed to be simple and straightforward to use, and the results are expected
to be rational for each decision-maker.
