Pollack’s principle of objective epistemic justification

Pollack’s principle of objective epistemic justification, whereby objective epistemic justification entails justified true belief, states that:

S is objectively justified in believing P if and only if:
1. S is (subjectively) justified in believing P; and
2. there is a set of X truths such that, given any more inclusive set Y of truths, necessarily, if the truths in Y were added to S’s beliefs (and their negations removed in those cases in which S disbelieves them) and S believed P for the same reason then he would still be (subjectively) justified in believing P.

In an example similar to Pollack’s Tom Grabit case, it becomes evident that the structure of epistemic justification and the complexity of epistemic norms is the crux for objective epistemic justification:

Suppose I see a sign indicating that the home of particular neighbor Mr. Beech is for sale on my street. I am sure that I am familiar with this neighbor who is an economics professor at the local college and know he lives there. The following day I arrive at work and report that Mr. Beech’s home is for sale, on the account that I have met him and seen a for sale sign on my street. However, unbeknownst to me, my wife insists that Mr. Beech is not moving anywhere, on account that she spoke with him the day before and he made no indication of doing so.

However, my wife did not know that Mr. Beech was ashamedly the victim on a Ponzi scheme and lost all him money, and that he desperately wanted to move to save face and needed to sell his house to recoup money. In light of this evidence, it becomes apparent that I did know that Mr. Beech was moving.

This example supports Pollack’s principle of objective epistemic justification because S instantiated argument A that objectively justified P so that A prevailed undefeated in relation to the inclusive set of truths presented. In the example, S is objectively justified in believing P as a result of knowledge that was undefeated by true defeaters.