Updating for Externalists

Mon, Apr 29, 2019, 5:30 pm
201 Marx Hall

Dmitri Gallow

University of Pittsburgh

Abstract: The character I’ll call 'the internalist' says that your evidence can never fail to tell you what your total evidence is. If your total evidence is e, then you must have the evidence that your total evidence is e. The character I’ll call 'the externalist' denies this. An update is a strategy for revising your degrees of belief, or credences, in response to the outcome of an experiment. The internalist has their update: upon learning e, adopt your pre-experimental credences conditional on e. This is the rule of conditionalization. Salow (forthcoming) teaches that if the externalist adopts conditionalization, then they will be capable of intentionally biasing their inquiry—for instance, designing experiments which are guaranteed to raise their credence that p as high as they like, independent of whether p is true or false. This is not rational inquiry, and no sensible epistemology will call it such. The externalist should reject conditionalization. So the externalist is in need of an update. I have one to offer. This update has maximal expected accuracy amongst those which the externalist should regard as genuinely available. If you abide by this update, then you will always satisfy the principle of Reflection; and, as a consequence, you will be incapable of intentionally biasing your inquiry.  (You will additionally always satisfy Elga's 'New Rational Reflection' principle.)  In experiments where the internalist has it right and your evidence will tell you what your total evidence is, this update agrees with conditionalization. It similarly agrees with the updates of Jeffrey (1965), Hild (1998), Schoenfield (forthcoming), and Gallow (2014) in the paradigm cases for which those updates were designed. 

Monday, April 29, 2019 -

5:30pm to 7:00pm

201 Marx Hall