Defeater Goes External.

This paper proposes a new externalist account of defeaters, in terms of reliable indicators, as an integral part of a unified externalist account of warrant and defeat. It is argued that posing externalist conditions on warrant, but internalist conditions on defeat lead to undesirable tensions. The proposal is contrasted to some rival accounts and then tested on some widely discussed cases, like the airport case. Misleading defeaters, where Laurence BonJour's reliable clairvoyants serve as examples, also receive treatment, partly because they illustrate how internalist constraints are inserted into the set up of the problem and therefore unduly constrain the domain of satisfactory solutions. Lastly, the proposal is defended against some objections. Firstly, that by posing externalist conditions on defeat, the account becomes too open. Secondly, that an externalist account fails to take into account the epistemic assessments of our fellows in the epistemic practice of forming beliefs and making epistemic claims, which can be based on accessible warrant only.