2021 Australasian Association of Philosophy Conference: 'Ignoring the Improbable', Mitchell Barrington, MPhil Student, Dianoia Institute of Philosophy, Australian Catholic University

Activity: PROFESSIONAL DEVELOPMENTConference AttendanceProfessional Development


Many problems in decision theory appear to be solvable if agents simply ignore some possibilities. The utility of this approach has given rise to a substantial number of theories endorsing “thresholdism”: the view that possibilities whose probability is below a particular threshold should be discounted entirely. However, ignoring possibilities—even extremely remote ones—comes at a hefty cost for one’s ability to make rational decisions. Firstly, when an outcome is excluded from an agent’s deliberations entirely, they will fail to be sensitive to differences in the probability and value of the excluded possibilities. Secondly, excluding an outcome from the decision problem prevents it from contributing to the expected value of other actions. This leads to implausible prescriptions with respect to these other actions. For instance, agents will be directed to take any bet against the excluded possibility, since they have assigned it a probability of 0.
Period6 Jul 2021