The Core Concepts of Epistemology
With the concepts of epistemically rational and justified belief situated within a philosophically respectable and perfectly general theory of rationality, and with knowledge understood as true belief plus adequate information, epistemology is reoriented.
The core concepts of the reoriented epistemology are true belief and epistemically rational belief. Knowledge and justified belief are derivative concepts1 explicated in terms of these core concepts together with human goals, needs, and values, which explains why the standards of both knowledge and justified belief become more demanding as the stakes go up. In the case of knowledge there cannot be important truths of which one is unaware, and in the case of justified belief the level of effort one expends in gathering evidence and deliberating should be commensurate with what it is epistemically rational to believe about the importance of the matter at hand.
The structure of epistemology can thus be represented by two conceptual chains. In Chain 1, the concept of epistemically rational belief in conjunction with considerations about the importance of the issue in question generates the concept of justified belief. In Chain 2, the concept of true belief in conjunction with considerations about the importance of truths one is aware of and not aware of generates the concept of knowledge.
Chain 1 is located within a general theory of rationality, at the heart of which is a template: an action A (decision, plan, strategy, or whatever) is rational in sense X for S if it is epistemically rational for S to believe that A will do an acceptably good job of satisfying her goals of type X. The template is perfectly general in the sense that it can be used to distinguish different kinds of rationality (economic rationality, rationality all things considered, epistemic rationality, etc.) and can also be used to understand the rationality of different kinds of phenomena (actions, decisions, plans, strategies, beliefs, etc.).
Chain 2 has been the primary focus of this book, the major thesis of which is that knowledge is a matter of having adequate information, where the test of adequacy is there being no important truths that one lacks.
There are no necessary links between the two chains, only contingent ones. This is so despite the fact that the defining goal of epistemically rational belief is that of now having true and comprehensive beliefs. So, when all goes well, epistemically rational beliefs are good candidates for knowledge.
Similarly for justified beliefs. Although practical considerations have an important role in determining what one justifiably believes, they do so by affecting the direction and extent of inquiry, after which they ordinarily drop out as irrelevant, with the aim then being to have true beliefs and avoid false ones. So once again, when things work out well, beliefs that are justified are plausible candidates for knowledge.
Things need not always work out, however. Beliefs can be epistemically rational and yet be mistaken, and so too can justified beliefs. They can even be thoroughly mistaken, as brain-in-the-vat and other such skeptical scenarios illustrate.
Nor is there a necessary link between knowledge and epistemic rationality or justification from the opposite direction. Neither epistemic rationality nor justification need enter into the explanation of when and how a true belief rises to the level of knowledge. To explain why S’s belief is an instance of knowledge, it is sufficient to note that it is true and she believes enough surrounding truths so that there is no important gap in her information. Nothing more is required.
To be sure, when S knows P, it is usually the case that she and her belief have various other merits. Her belief may be justified; it may have been reliably produced; it may track the truth in close counterfactual situations; S herself may have been meticulous in gathering evidence about P; she may have been appropriately careful and thorough in deliberating about this evidence; and she may possess various intellectual virtues that played a role in her coming to believe P. These merits are not required to explain why she knows P, however. Except in a few rare and strange situations in which knowledge is blocked, S knows P if she believes P, P is true, and there are no important truths she lacks.