- Beliefs which are “close to experience” (or on the “periphery” of the Quinian web).
- Beliefs that are in the interior of the web.
Is the a priori way out the only way out?
And if we accept BonJour’s prognosis of the rejection of the a priori vis-à-vis Quinian webs of belief (or any such parallel systems), then it's no surprise the BonJour thinks “the rejection of all a priori justification is tantamount to intellectual suicide”.
Yes, fair enough, evidence is of supreme importance in science and in just about every other disciple. However, without the framework of a priori logic, all this evidence would amount to nothing.
Indeed it wouldn't even be evidence “for or against anything” if it weren't for such logical frameworks. (Or the logical links between this belief and that belief; or between this bit of evidence and that bit of evidence.) Logic ties the whole thing together.
That's why philosophers have said that “the logic of science” isn't itself scientific (or a science). Science and even naturalism (or empiricism) require logic. Thus science and empiricism (or naturalism) also require the a priori (or a priori justification).
“'links that hold the web of belief together reflect a set of rules that are part of “an evidential system”’.
That means that the links between beliefs in a system (or wherever) provide a “set of rules” (which the links must abide by) within what Field calls an “evidential system”. There would be no system (or web) without those links. Therefore, according to BonJour, there would be no system (or web) at all without the a priori.
Devitt, Michael, 'There is no a Priori' (2005)