just to say that p is supportable to some extent by your overall evidential reasons. This construal will be non-normative so long as the notions of supportability and an evidential reason are nonnormative. Some philosophers have tried to explicate the latter notions without relying on talk of epistemic permissibility or epistemic goodness. We can understand the relevant notion of ‘support’ in terms of non-normative notions of entailment and explanation (or, answering why-questions). We can understand the notion of an ‘evidential reason’ via the notion of a psychological state that can stand in a certain truth-indicating support relation to propositions. For instance, we might regard nondoxastic states of ‘seeming to perceive’ something (e.g., seeming to see a dictionary here) as foundational truth indicators for certain physical-object propositions (e.g., the proposition that there is a dictionary here), in virtue of those states being best explained by those propositions. If anything resembling this approach succeeds, we can get by without the aforementioned normative notions of epistemic justification. Foundationalism versus coherentism. Talk of foundational truth indicators brings us to a key controversy over justification: Does epistemic justification, and thus knowledge, have foundations, and if so, in what sense? This question can be clarified as the issue whether some beliefs can not only (a) have their epistemic justification non-inferentially (i.e., apart from evidential support from any other beliefs), but also (b) provide epistemic justification for all justified beliefs that lack such non-inferential justification. Foundationalism gives an affirmative answer to this issue, and is represented in varying ways by, e.g., Aristotle, Descartes, Russell, C. I. Lewis, and Chisholm. Foundationalists do not share a uniform account of non-inferential justification. Some construe non-inferential justification as self-justification. Others reject literal self-justification for beliefs, and argue that foundational beliefs have their non-inferential justification in virtue of evidential support from the deliverances of non-belief psychological states, e.g., perception (‘seem-ing-to-perceive’ states), sensation (‘seeming-to-sense’ states), or memory (‘seeming-toremember’ states). Still others understand noninferential justification in terms of a belief’s being ‘reliably produced,’ i.e., caused and sustained by some non-belief belief-producing process or source (e.g., perception, memory, introspection) that tends to produce true rather than false beliefs. This last view takes the causal source of a belief to be crucial to its justification. Unlike Descartes, contemporary foundationalists clearly separate claims to non-inferential, foundational justification from claims to certainty. They typically settle for a modest foundationalism implying that foundational beliefs need not be indubitable or infallible. This contrasts with the radical foundationalism of Descartes.
The traditional competitor to foundationalism is the coherence theory of justification, i.e., epistemic coherentism. This is not the coherence definition of truth; it rather is the view that the justification of any belief depends on that belief’s having evidential support from some other belief via coherence relations such as entailment or explanatory relations. Notable proponents include Hegel, Bosanquet, and Sellars. A prominent contemporary version of epistemic coherentism states that evidential coherence relations among beliefs are typically explanatory relations. The rough idea is that a belief is justified for you so long as it either best explains, or is best explained by, some member of the system of beliefs that has maximal explanatory power for you. Contemporary coherentism is uniformly systemic or holistic; it finds the ultimate source of justification in a system of interconnected beliefs or potential beliefs.
One problem has troubled all versions of coherentism that aim to explain empirical justification: the isolation argument. According to this argument, coherentism entails that you can be epistemically justified in accepting an empirical proposition that is incompatible with, or at least improbable given, your total empirical evidence. The key assumption of this argument is that your total empirical evidence includes non-belief sensory and perceptual awareness-states, such as your feeling pain or your seeming to see something. These are not belief-states. Epistemic coherentism, by definition, makes justification a function solely of coherence relations between propositions, such as propositions one believes or accepts. Thus, such coherentism seems to isolate justification from the evidential import of non-belief awareness-states. Coherentists have tried to handle this problem, but no resolution enjoys wide acceptance. Causal and contextualist theories. Some contemporary epistemologists endorse contextualism regarding epistemic justification, a view suggested by Dewey, Wittgenstein, and Kuhn, among others. On this view, all justified beliefs depend for their evidential support on some unjustified beliefs that need no justification. In any context of inquiry, people simply assume (the acceptability of) some propositions as starting points for inquiry, and these ‘contextually basic’ propositions, though lacking evidential support, can serve as evidential support for other propositions. Contextualists stress that contextually basic propositions can vary from context to context (e.g., from theological inquiry to biological inquiry) and from social group to social group. The main problem for contextualists comes from their view that unjustified assumptions can provide epistemic justification for other propositions. We need a precise explanation of how an unjustified assumption can yield evidential support, how a non-probable belief can make another belief probable. Contextualists have not given a uniform explanation here. Recently some epistemologists have recommended that we give up the traditional evidence condition for knowledge. They recommend that we construe the justification condition as a causal condition. Roughly, the idea is that you know that p if and only if (a) you believe that p, (b) p is true, and (c) your believing that p is causally produced and sustained by the fact that makes p true. This is the basis of the causal theory of knowing, which comes with varying details. Any such causal theory faces serious problems from our knowledge of universal propositions. Evidently, we know, for instance, that all dictionaries are produced by people, but our believing that this is so seems not to be causally supported by the fact that all dictionaries are humanly produced. It is not clear that the latter fact causally produces any beliefs. Another problem is that causal theories typically neglect what seems to be crucial to any account of the justification condition: the requirement that justificational support for a belief be accessible, in some sense, to the believer. The rough idea is that one must be able to access, or bring to awareness, the justification underlying one’s beliefs. The causal origins of a belief are, of course, often very complex and inaccessible to a believer. Causal theories thus face problems from an accessibility requirement on justification. Internalism regarding justification preserves an accessibility requirement on what confers justification, whereas epistemic externalism rejects this requirement. Debates over internalism and externalism abound in current epistemology, but internalists do not yet share a uniform detailed account of accessibility.
The Gettier problem. The standard analysis of knowledge, however elaborated, faces a devastating challenge that initially gave rise to causal theories of knowledge: the Gettier problem. In 1963 Edmund Gettier published a highly influential challenge to the view that if you have a justified true belief that p, then you know that p. Here is one of Gettier’s counterexamples to this view: Smith is justified in believing the false proposition that (i) Jones owns a Ford. On the basis of (i), Smith infers, and thus is justified in believing, that (ii) either Jones owns a Ford or Brown is in Barcelona. As it happens, Brown is in Barcelona, and so (ii) is true. So, although Smith is justified in believing the true proposition (ii), Smith does not know (ii).
Gettier-style counterexamples are cases where a person has justified true belief that p but lacks knowledge that p. The Gettier problem is the problem of finding a modification of, or an alternative to, the standard analysis that avoids difficulties from Gettier-style counterexamples. The controversy over the Gettier problem is highly complex and still unsettled. Many epistemologists take the lesson of Gettier-style counterexamples to be that propositional knowledge requires a fourth condition, beyond the justification, truth, and belief conditions. No specific fourth condition has received overwhelming acceptance, but some proposals have become prominent. The so-called defeasibility condition, e.g., requires that the justification appropriate to knowledge be ‘undefeated’ in the general sense that some appropriate subjunctive conditional concerning defeaters of justification be true of that justification. For instance, one simple defeasibility fourth condition requires of Smith’s knowing that p that there be no true proposition, q, such that if q became justified for Smith, p would no longer be justified for Smith. So if Smith knows, on the basis of his visual perception, that Mary removed books from the library, then Smith’s coming to believe the true proposition that Mary’s identical twin removed books from the library would not undermine the justification for Smith’s belief concerning Mary herself. A different approach shuns subjunctive conditionals of that sort, and contends that propositional knowledge requires justified true belief that is sustained by the collective totality of actual truths. This approach requires a detailed account of when justification is undermined and restored. The Gettier problem is epistemologically important. One branch of epistemology seeks a precise understanding of the nature (e.g., the essential components) of propositional knowledge. Our having a precise understanding of propositional knowledge requires our having a Gettier-proof analysis of such knowledge. Epistemologists thus need a defensible solution to the Gettier problem, however complex that solution is. Skepticism. Epistemologists debate the limits, or scope, of knowledge. The more restricted we take the limits of knowledge to be, the more skeptical we are. Two influential types of skepticism are knowledge skepticism and justification skepticism. Unrestricted knowledge skepticism implies that no one knows anything, whereas unrestricted justification skepticism implies the more extreme view that no one is even justified in believing anything. Some forms of skepticism are stronger than others. Knowledge skepticism in its strongest form implies