- If p partly grounds q and p is explanatorily irrelevant to r, then q does not strictly explain r.
- Something's being ungettiered is explanatorily irrelevant to all philosophically important facts, except for knowledge facts.
- That one's belief that p is ungettiered partly grounds that one knows p.
- So facts about what one knows do not strictly explain anything philosophically important.
So, in the order of explanation among philosophically important facts, knowledge facts come last, if at all.