Consider the following principle, one lifted from the same Feldman piece that prompted the last post:
Evidence that there is evidence for P is evidence for P.
I’ll call this principle the “metaevidence” principle. According to this principle, no matter how many repetitions of the phrase ‘there is evidence for’ precede P, it is always true that there is evidence for P.
If the metaevidence principle is true, then evidence and probability look quite different. Suppose it is probable that it is probable that P; it doesn’t follow from this claim that it is probable that P (since a claim can be probable and false). But doesn’t this same reason count against the metaevidence principle? That is, can’t there be evidence for something false? Of course there can. So why do things change when the claim is itself a claim about evidence?