Take the term ‘justified’ as one of the following:
- S adopts a belief in an epistemically responsible manner (call this the ‘responsibility clause’).
- A relationship between the proposition believed and the grounds on which it is believed by S (call this the ‘grounds clause’).
As I will show, both clauses are needed in a plausible account of knowledge. The justification clause in the traditional doctrine that knowledge equals justified true belief must have these two components (1, 2). Furthermore, if 1 and 2 are satisfied, then the belief and truth clauses are reducible to the grounds and responsibility clauses — they will be necessarily believed and be true. The first part of this two-parter will show that the responsibility clause is not sufficient for a justificationist account of knowledge.
Take the classic Gettier counter-example from Ernest Sosa (“Epistemic Presuppositions,” 1979, 84. ):
Out for a drive in the country, I see a barn nearby standing out from its surroundings in sharp focus, and thus perceptually acquire the fully justified belief that it is a barn. In both directions along my road there are numerous barn facsimiles, however, mere shells presenting to the road a facade that would draw an attribution of barnhood no less justified than my own when by luck I happened to take notice of the one real barn in the area. Surely my justified true belief that I see a barn is not knowledge.
Susan will be justified in her belief, having come to it in a responsible manner, meaning that her performance will satisfy the responsibility clause. At the same time, her grounds will not establish the truth of what she believes, so the grounds clause will not be satisfied.
If Susan believes something on grounds that do not establish its truth, is that enough to show that she has formed her belief irresponsibly? Assume that is not the case: statements are justified solely by the responsibility clause; however, on occasion Susan will form false — but justified — beliefs, due to Susan’s ignorance. Susan searches as best she can to come to a correct result, she performs admirably, but she misses something important. If she had a wider range of information, she would have acted differently. Do justificationists want knowledge to count as well-intended ignorance? Of course not. Therefore, if Susan believes something on grounds that do not establish its truth, Susan has formed her belief irresponsibly.
Using the Sosa/Gettier counter-example, Susan is using a normally reliable procedure in a context where it is not reliable, then arriving at a true conclusion by good fortune. Susan is justified in believing that the barn is a barn, and not in fact a barn-facsimile due to epistemic luck, and luck should not be a significant part of knowledge. Therefore, the responsibility clause is necessary for knowledge under the justificationist account of knowledge, but not sufficient. We require the grounds clause.