Arguing for Decisions: A Qualitative Model of Decision Making

We develop a qualitative model of decision making with two aims: to describe how peo­ ple make simple decisions and to enable com­ puter programs to do the same. Current ap­ proaches based on Planning or Decision The­ ory either ignore uncertainty and tradeoffs, or provide languages and algorithms that are too complex for this task. The proposed model provides a language based on rules, a semantics based on high probabilities and lexicographical preferences, and a transpar­ ent decision procedure where reasons for and against decisions interact. The model is no substitute for Decision Theory, yet for deci­ sions that people find easy to explain it may provide an appealing alternative.