So knowledge of PQTI suffices in principle for conclusive knowledge of M, with no other empirical information required.
As before, a priori knowledge of PQTI [contains] M does not rely on any explicit analysis of the concepts involved in M, or on any explicit bridging principles connecting the vocabulary of PQTI with the vocabulary of M.
It might be objected that we do not yet have a completed physics, so that we do not yet know what P says, so we cannot know whether PQTI implies M.
It might also be objected that no human could grasp all the information in PQTI, so that no human could grasp the truth of the relevant conditional.
The virtual world does no more than give access to the information contained in PQTI and process this information on a priori grounds.
One might ask: given that PQTI implies ordinary macroscopic truths, does similar reasoning suggest that PTI alone implies many such truths?
17) Whether or not these reasons are sound, their existence makes it clear that there is no direct argument that PTI implies Q analogous to the argument concerning PQTI above.
Note that we have not argued here that PQTI implies every truth in every domain (although we are inclined to accept this claim).
The information in PQTI itself is knowable only a posteriori; and simplicity considerations play a central role in our coming to know aspects of this information.
For relevant truths M: (i) a subject can know an application conditional PQTI [contains] M from the armchair; (ii) there is some general empirical information E, acquired at some time in the past, that plays a role in justifying the subject's knowledge of the conditional; and (iii) empirical knowledge such as E plays an essential role in justifying knowledge of the conditional.
That is, E might itself be implied by PQTI, and one could then straightforwardly use E in combination with PQTI to deduce M.
To examine this matter in the context of the current objection, we will take it for granted that considerations earlier in the paper establish that for empirical truths M, the conditional PQTI [contains] M is at least knowable from the armchair.