Professor Thomas Grundmann University of Cologne

Event details

In Defense of Higher-Order Defeat

(joint work with Marvin Backes)

Ordinary defeaters remove justification by either providing counterevidence (rebutting defeaters) or weakening evidential support (undermining defeaters). Recently, it has been noticed that there is a kind of defeat that functions differently: higher-order defeat. Suppose you calculate properly but then receive the misleading evidence that, most likely, you did not calculate properly, for instance due to an intoxication that imperceptibly impaired your calculation skills. In this case, defeat seems to work without providing counterevidence or weakening your evidential support. The latter becomes obvious if you accept that conclusive mathematical evidence functions monotonically and hence cannot be weakened by adding further evidence. Higher-order defeat is strongly relevant to the epistemology of disagreement, the epistemology of epistemic authority and rational responses to recognized cognitive biases. In a seminal paper, Maria Lasonen-Aarnio (2014) has argued that there is no such thing as higher-order defeat. Among her many interesting objections to higher-order defeat two of them stand out particularly. First, she claims that higher-order defeat would make it impossible to articulate necessary and sufficient conditions of justification. Second, she argues that within the evidentialist framework higher-order defeat cannot be explained. 

In our joint paper, Marvin Backes and I respond to these challenges. Against her first challenge, we argue that Lasonen-Aarnio’s reductio of higher-order defeat can be avoided. Against her second challenge, we explain how different kinds of evidentialism can explain higher-order defeat. If we are on the right track, such an explanation is compatible with both, more objective and more subjective accounts of evidence. 

This is a Philosophy Colloquium Event.