Recursive Tracking versus Process Reliabilism

Sherrilyn Roush’s Tracking Truth (2005) is an impressive, precisioncrafted work. Although it sets out to rehabilitate the epistemological theory of Robert Nozick’s Philosophical Explanations (1981), its departures from Nozick’s line are extensive and original enough that it should be regarded as a distinct form of epistemological externalism. Roush’s mission is to develop an externalism that averts the problems and counterexamples encountered not only by Nozick’s theory but by other varieties of externalism as well. Roush advances both a theory of knowledge and a theory of evidence; I focus entirely on knowledge. I shall pinpoint a few respects in which Roush’s theory is not wholly successful. In particular, it works less well than process(or method-) oriented externalisms like process reliabilism. Nozick’s initial tracking account of knowledge was formulated as follows: