(LII) Gettier Problems

Not long ago, most philosophers were content to think of knowledge as "justified true belief." After the publication of Edmund Gettier's 3-page essay raising doubts about justification, the situation became a bit more complex. Here's one example (from an article by W. Lycan):

S has nonbasic knowledge that p iff (i) p is true; (ii) S believes that p; (iii) S’s justification renders p evident for S;…(iv*) [w]here ‘e’ designates the portion of S’s total evidence E that is immediately relevant to the justification of p, either (A) there is a nondefective causal chain from P to BSe; or (B) there is some event or state of affairs Q such that (i) there is a nondefective causal chain from Q to BSe; and (ii) there is a nondefective causal chain from Q to P; or (C) there is some event or state of affairs H such that (i) there is a nondefective causal chain from H to BSe; and (ii) H is a nondefective pseudo-overdeterminant of P. [Where a causal chain X ? Y is ‘defective’ with respect to S’s justification for p based on evidence e iff: Either (I) (a) there is some event or state of affairs U in X ? Y such that S would be justified in believing that U did not occur and (b) it is essential to S’s justifiably believing that p on the basis of the evidence e that S would be justified in believing that U did not occur; or (II) there is some significant alternative C* to X ? Y with respect to S justifiably believing that p on the basis of e. [Where C* is a ‘significant alternative’ to X ? Y with respect to S justifiably believing that p on the basis of e if (a) it is objectively likely that C* should have occurred rather than X ? Y ; and (b) if C* had occurred instead of X ? Y, then there would have been an event or state of affairs U in C* such that S would not be justified in believing that p if S were justified in believing that U occurred.]