John,

Thanks.

What I meant when saying that the internalist and externalist might be 'arguing past each other' is that they are both partially right.  It occurs to me upon perusing your thesis that there are more ways to 'argue past each other' than merely to have a merely-verbal dispute with one another. 

Compare with this case: three blind men feel different parts of an elephant; one says 'it's like a wall', the second says 'it's like a snake', and the third says 'it's like a tree'.  These guys are arguing past each other at least insofar as, if they were to get a fuller picture of the truth of the matter, they would see that they get approximate 'proportions' of it correct (as it were).

I think that something similar is going on between externalists and internalists.  (The following statement from your dissertation seems to agree: "Though there are ways in which particular internalist/externalist debates could be compatible, there are also incompatible ones.")

My view is roughly as follows.  [1] In one loose sense of justification, which applies in some contexts but not in others, either externalist or internalist justification is sufficient for justification tout court.  [2] In other contexts, externalist but not internalist justification is sufficient, and [3] in yet other contexts, internalist but not externalist justification is sufficient for justification tout court.  Finally, [4] in still other contexts, internalist and externalist justification are individually necessary and jointly sufficient for justification tout court.

If I'm right, then the following things are true.  [CASE SD1] Suppose someone says, 'internalist justification is the only legitimate type of justification', and someone else responds, 'externalist justification is the only legitimate type of justification'.  These parties have both asserted false theses.  Their dispute is genuine, but they are both approximately equally right about the nature of justification tout court.  So in that sense, they are 'arguing past each other', even though their dispute is not merely-verbal, but substantive.

[CASE VD1] Suppose, however, that one party says 'internalist justification is necessary for justification tout court' and another says 'externalist justification is necessary for justification tout court'.  These parties obviously don't disagree about anything substantive, and are hence having a merely verbal dispute, since it could turn out that all cases are of type [4].  On my view, of course, this is false--there are also situations of type [2] which the internalist party here is wrong about and, and situations of type [3] which the externalist party here is wrong about.

[CASE VD2] Another case where the dispute would be merely-verbal is this: the externalist says 'justification tout court is thus-and-so', and the internalist says 'no, justificaiton tout court is thus-and-such'--but the externalist is thinking of cases of type [2], while the internalist is thinking of cases of type [3].  Then they're talking in the abstract, using similar terms, but the claims they make are not about the same types of scenarios.  That seems like a merely-verbal dispute.  I think that this happens a lot in the literature (although I can' t claim to have mastered the literature on this).

What is tricky is that, for some cases, like [2] and [3], one party is completely right, and the other completely wrong.  But switch to a case of type [1], and both parties are right that their version is sufficient for justification (but only partially, since theirs isn't the only sufficient kind).  And switch to a case of type [4], and both parties are right that their version is necessary for justification (but only partially, since theirs isn't the only necessary element).

Note that, if what I have said is correct, a lot of the substantiveness of future disputes about internalism and externalism will turn on which cases are of each type, [1]-[4].  But the advantage of this framework is that single examples won't be taken as decisive for settling the debate completely.  Numerous cases must be considered--some where the stakes and likelihood of challenge to the belief are very low, others where they are much higher, and others between these extremes.

So: kumbaya.

What do you think?