Publisher Summary This chapter discusses defeasible reasoning for decisions, which is the
natural extension of philosophers' defeasible practical reasoning about action. The
difference in it is that the arguments for actions are quantitative, often invoking expected
utility calculations. In practical reasoning, reasoning about action is qualitative. If an act
achieves a goal, that is a reason for performing that act. If an act achieves a goal but also
invokes a penalty and that penalty is more undesirable than the goal itself, then that may be …

In two recent papers, I have proposed a description of decision analysis that differs from the
Bayesian picture painted by Savage, Jeffrey and other classic authors. Response to this
view has been either overly enthusiastic or unduly pessimistic. In this paper I try to place the
idea in its proper place, which must be somewhere in between. Looking at decision analysis
as defeasible reasoning produces a framework in which planning and decision theory can
be integrated, but work on the details has barely begun. It also produces a framework in …