1.1 Knowledge as Justified True Belief
There are various kinds of knowledge: knowing how to do something (for example, how to ride a bicycle), knowing someone in person, and knowing a place or a city. Although such knowledge is of epistemological interest as well, we shall focus on knowledge of propositions and refer to such knowledge using the schema ‘S knows that p’, where ‘S’ stands for the subject who has knowledge and ‘p’ for the proposition that is known. Our question will be: What are the necessary and sufficient conditions for S to know that p? We may distinguish, broadly, between a traditional and a non-traditional approach to answering this question. We shall refer to them as ‘TK’ and ‘NTK’.
According to TK, knowledge that p is, at least approximately, justified true belief (JTB). False propositions cannot be known. Therefore, knowledge requires truth. A proposition S doesn't even believe can't be a proposition that S knows. Therefore, knowledge requires belief. Finally, S's being correct in believing that p might merely be a matter of luck. Therefore, knowledge requires a third element, traditionally identified as justification. Thus we arrive at a tripartite analysis of knowledge as JTB: S knows that p if and only if p is true and S is justified in believing that p. According to this analysis, the three conditions — truth, belief, and justification — are individually necessary and jointly sufficient for knowledge.
Initially, we may say that the role of justification is to ensure that S's belief is not true merely because of luck. On that, TK and NTK are in agreement. They diverge, however, as soon as we proceed to be more specific about exactly how justification is to fulfill this role. According to TK, S's belief that p is true not merely because of luck when it is reasonable or rational, from S's own point of view, to take p to be true. According to evidentialism, what makes a belief justified in this sense is the possession of evidence. The basic idea is that a belief is justified to the degree it fits S's evidence. NTK, on the other hand, conceives of the role of justification differently. Its job is to ensure that S's belief has a high objective probability of truth and therefore, if true, is not true merely because of luck. One prominent idea is that this is accomplished if, and only if, a belief originates in reliable cognitive processes or faculties. This view is known as reliabilism.
1.2 The Gettier Problem
The tripartite analysis of knowledge as JTB has been shown to be incomplete. There are cases of JTB that do not qualify as cases of knowledge. JTB, therefore, is not sufficient for knowledge. Cases like that — known as Gettier-cases — arise because neither the possession of evidence nor origination in reliable faculties is sufficient for ensuring that a belief is not true merely because of luck. Consider the well-known case of barn-facades: Henry drives through a rural area in which what appear to be barns are, with the exception of just one, mere barn facades. From the road Henry is driving on, these facades look exactly like real barns. Henry happens to be looking at the one and only real barn in the area and believes that there's a barn over there. Henry's belief is justified, according to TK, because Henry's visual experience justifies his belief. According to NTK, his belief is justified because Henry's belief originates in a reliable cognitive process: vision. Yet Henry's belief is plausibly viewed as being true merely because of luck. Had Henry noticed one of the barn-facades instead, he would also have believed that there's a barn over there. There is, therefore, broad agreement among epistemologists that Henry's belief does not qualify as knowledge.
To state conditions that are jointly sufficient for knowledge, what further element must be added to JTB? This is known as the Gettier problem. According to TK, solving the problem requires a fourth condition. According to some NTK theorists, it calls for refining the concept of reliability. For example, if reliability could suitably be indexed to the subject's environment, reliabilists could say that Henry's belief is not justified because in his environment, vision is not reliable when it comes to discerning barns from barn-facades.
Some NTK theorists bypass the justification condition altogether. They would say that, if we conceive of knowledge as reliably produced true belief, there is no need for justification. Reliabilism, then, comes in two forms: as a theory of justification or as a theory of knowledge. As the former, it views justification to be an important ingredient of knowledge but, unlike TK, grounds justification solely in reliability. As a theory of knowledge, reliabilism asserts that justification is not necessary for knowledge; rather, reliably produced true belief (provided the notion of reliability is suitably refined to rule out Gettier cases) is sufficient for it.
2. What is Justification?
When we discuss the nature of justification, we must distinguish between two different issues: First, what do we mean when we use the word ‘justification’? Second, what makes beliefs justified? It is important to keep these issues apart because a disagreement on how to answer the second question will be a mere verbal dispute, if the disagreeing parties have different concepts of justification in mind. So let us first consider what we might mean by ‘justification’ and then move on to the non-definitional issues.
2.1 Deontological and Non-Deontological Justification
How is the term ‘justification’ used in ordinary language? Here is an example: Tom asked Martha a question, and Martha responded with a lie. Was she justified in lying? Jane thinks she was, for Tom's question was an inappropriate one, the answer to which was none of Tom's business. What might Jane mean when she thinks that Martha was justified in responding with a lie? A natural answer is this: She means that Martha was under no obligation to refrain from lying. Due the inappropriateness of Tom's question, it wasn't Martha's duty to tell the truth. This understanding of justification, commonly labeled deontological, may be defined as follows: S is justified in doing x if and only if S is not obliged to refrain from doing x.
Suppose, when we apply the word justification not to actions but to beliefs, we mean something analogous. In that case, the term ‘justification’ as used in epistemology would have to be defined this way:
Deontological Justification (DJ)
S is justified in believing that p if and only if S believes that p while it is not the case that S is obliged to refrain from believing that p.
What kind of obligations are relevant when we wish to assess whether a belief, rather than an action, is justified or unjustified? Whereas when we evaluate an action, we are interested in assessing the action from either a moral or a prudential point of view, when it comes to beliefs, what matters is the pursuit of truth. The relevant kinds of obligations, then, are those that arise when we aim at having true beliefs. Exactly what, though, must we do in the pursuit of this aim? According to one answer, the one favored by evidentialists, we ought to believe in accord with our evidence. For this answer to be helpful, we need an account of what our evidence consists of. According to another answer, we ought to follow the correct epistemic norms. If this answer is going to help us figure out what obligations the truth-aim imposes on us, we need to be given an account of what the correct epistemic norms are.
The deontological understanding of the concept of justification is common to the way philosophers such as Descartes, Locke, Moore and Chisholm have thought about justification. Today, however, the dominant view is that the deontological understanding of justification is unsuitable for the purposes of epistemology. Two chief objections have been raised against conceiving of justification deontologically. First, it has been argued that DJ presupposes that we can have a sufficiently high degree of control over our beliefs. But beliefs are akin not to actions but rather things such as digestive processes, sneezes, or involuntary blinkings of the eye. The idea is that beliefs simply arise in or happen to us. Therefore, beliefs are not suitable for deontological evaluation. To this objection, some advocates of DJ have replied that lack of control over our beliefs is no obstacle to using the term ‘justification’ in its deontological sense. Others have argued that it's a mistake to think that we can control our beliefs any less than our actions.
According to the second objection to DJ, deontological justification does not tend ‘epistemize’ true beliefs: it does not tend to make them non-accidentally true. This claim is typically supported by describing cases involving either a benighted, culturally isolated society or subjects who are cognitively deficient. Such cases involve beliefs that are claimed to be epistemically defective even though it would not seem that the subjects in these cases are under any obligation to refrain from believing as they do. What makes the beliefs in question epistemically defective is that they are formed using unreliable and intellectually faulty methods. The reason why the subjects, from their own point of view, are not obliged to believe otherwise is that they are either cognitively deficient or live in a benighted and isolated community. DJ says that such beliefs are justified. If they meet the remaining necessary conditions, DJ-theorists would have to count them as knowledge. According to the objection, however, the beliefs in question, even if true, could not possibly qualify as knowledge, due to the epistemically defective way they were formed. Consequently, DJ must be rejected.
Those who reject DJ use the term ‘justification’ in a technical sense that deviates from how the word is ordinarily used. The technical sense is meant to make the term suitable for the needs of epistemology. But how are we then to conceive of justification? What does it mean for a belief to be justified in a non-deontological sense? Recall that the role assigned to justification is that of ensuring that a true belief isn't true merely by accident. Let us say that this is accomplished when a true belief instantiates the property of proper probabilification. We may, then, define non-deontological justification as follows:
Non-Deontological Justification (NDJ)
S is justified in believing that p if and only if S believes that p on a basis that properly probabilifies S's belief that p.
If we wish to pin down exactly what probabilification amounts to, we will have to deal with a variety of tricky issues. For now, let us just focus on the main point. Those who prefer NDJ to DJ would say that probabilification and deontological justification can diverge: it's possible for a belief to be deontologically justified without being properly probabilified. This is just what cases involving benighted cultures or cognitively deficient subjects are supposed to show.
2.2 Evidence vs. Reliability
What makes justified beliefs justified? According to evidentialists, it is the possession of evidence. What is it, though, to possess evidence for believing that p? Some evidentialists would say it is to be in a mental state that represents p as being true. For example, if the coffee in your cup tastes sweet to you, then you have evidence for believing that the coffee is sweet. If you feel a throbbing pain in your head, you have evidence for believing that you have a headache. If you have a memory of having had cereal for breakfast, then you have evidence for a belief about the past: a belief about what you ate when you had breakfast. And when you clearly "see" or "intuit" that the proposition "If Jack had more than four cups of coffee, then Jack had more than three cups of coffee" is true, then you have evidence for believing that proposition. In this view, evidence consists of perceptual, introspective, memorial, and intuitional experiences, and to possess evidence is to have an experience of that kind. So according to this evidentialism, what makes you justified in believing that p is your having an experience that represents p as being true.
Many reliabilists, too, would say that the experiences mentioned in the previous paragraph matter. However, they would deny that justification is solely a matter of having suitable experiences. Rather, they hold that a belief is justified if, and only if, it results from cognitive origin that is reliable: an origin that tends to produce true beliefs and therefore properly probabilifies the belief. Reliabilists, then, would agree that the beliefs mentioned in the previous paragraph are justified. But according to a standard form of reliabilism, what makes them justified is not the possession of evidence, but the fact that the types of processes in which they originate — perception, introspection, memory, and rational intuition — are reliable.
2.3 Internal vs. External
In contemporary epistemology, there has been an extensive debate on whether justification is internal or external. Internalists claim that it is internal; externalists deny it. How are we to understand these claims?
To understand what the internal-external distinction amounts to, we need to bear in mind that, when a belief is justified, there is something that makes it justified. Likewise, if a belief is unjustified, there is something that makes it unjustified. Let's call the things that make a belief justified or unjustified J-factors. The dispute over whether justification is internal or external is a dispute about what the J-factors are.
Among those who think that justification is internal, there is no unanimity on how to understand the concept of internality. We can distinguish between two approaches. According to the first, justification is internal because we enjoy a special kind of access to J-factors: they are always recognizable on reflection. Hence, assuming certain further premises (which will be mentioned momentarily), justification itself is always recognizable on reflection. According to the second approach, justification is internal because J-factors are always mental states. Let's call the former accessibility internalism and the latter mentalist internalism. Externalists deny that J-factors meet either one of these conditions.
Evidentialism is typically associated with internalism, and reliabilism with externalism. Let us see why. Evidentialism says, at a minimum, two things:
E1 Whether one is justified in believing p depends on one's evidence regarding p.
E2 One's evidence consists of one's mental states.
By virtue of E2, evidentialism is obviously an instance of mentalist internalism.
Whether evidentialism is also an instance of accessibility internalism is a more complicated issue. The conjunction of E1 and E2 by itself implies nothing about the recognizability of justification. Recall, however, that in Section 1.1 we distinguished between TK and NTK: the traditional and the nontraditional approach to the analysis of knowledge and justification. TK advocates, among which evidentialism enjoys widespread sympathy, tend to endorse the following two claims:
One's own mind is cognitively luminous: Relying on introspection, one can always recognize on reflection what mental states one is in.
a priori recognizable, necessary principles say what is evidence for what. Relying on a priori insight, one can therefore always recognize on reflection whether one's mental states are evidence for p.
Although E1 and E2 by themselves do not imply access internalism, it is quite plausible to maintain that evidentialism, when embellished with Luminosity and Necessity, becomes an instance of access internalism.
Next, let us consider why reliabilism is an externalist theory. Reliabilism says that the justification of one's beliefs is a function of, not one's evidence, but the reliability of one's belief sources such as memorial, perceptual and introspective states and processes. Whereas the sources might qualify as mental, their reliability does not. Therefore, reliabilists reject mentalist internalism. Moreover, if the justification of one's beliefs is determined by the reliability of one's belief sources, justification will not always be recognizable on reflection. Hence reliabilists reject access internalism as well.
Let's use an example of radical deception to illustrate the difference between evidentialism as an internalist theory and reliabilism as an externalist theory. If evidentialism is true, a subject who is radically deceived will be mislead about what is actually the case, but not about what he is justified in believing. If, on the other hand, reliabilism is true, then such a subject will be misled about both what is actually the case and what he is justified in believing. Let us see why.
Distinguish between Tim and Tim*: one and the same person whom we imagine in two altogether different situations. Tim's situation is normal, like yours or mine. Tim*, however, is a brain in a vat. Suppose a mad scientist abducted and "envatted" Tim* by removing his brain from his skull and putting it in a vat in which his brain is kept alive. Next, the mad scientist connects the nerve endings of Tim*'s brain with wires to a machine that, controlled by a powerful computer, starts stimulating Tim*'s brain in such a way that Tim* does not notice what actually happened to him. He is going to have perfectly ordinary experiences, just like Tim. Indeed, let's assume that the mental states of Tim and the mental states of Tim* are alike. But, since Tim* is a brain in a vat, he is, unlike Tim, radically deceived about his actual situation. For example, when Tim believes he has hands, he is right. When Tim* believes he has hands, he is mistaken. (His hands were discarded, along with the rest of his limbs and torso.) When Tim believes he is drinking coffee, he is right. When Tim* believes he is drinking coffee, he is mistaken. (Brains don't drink coffee.) Now suppose Tim* asks himself whether he is justified in believing that he has hands. Since Tim* is just like Tim, Tim* will say that his belief is justified, just as Tim would if he were to ask himself whether he is justified in believing that he has hands. Evidentialism implies that Tim*'s answer is correct. For even though he is deceived about his external situation, he is not deceived about his evidence: the way things appear to him in his experiences. This illustrates the internality of evidentialist justification. Reliabilism, on the other hand, suggests that Tim*'s answer is incorrect. Tim*'s belief that he has hands originates in cognitive processes — "seeing" and "feeling" his (nonexisting) hands — that now yield virtually no true beliefs. To the extent that this implies their unreliability, the resulting beliefs are unjustified. Consequently, he is deceived not only about his external situation (his not having hands), but also about the justificational status of his belief that he has hands. This illustrates the externality of reliabilist justification.
The example of Tim and Tim* may serve as well to illustrate a further way in which we may conceive of the difference between internalism and externalism. Some internalists take the following principle to be characteristic of the internalist point of view:
If two subjects, S and S*, are alike mentally, then the justificational status of their beliefs is alike as well: the same beliefs are justified or unjustified for them to the same extent.
When we apply this principle to the Tim/Tim* example, it tells us that evidentialism is an internalist and reliabilism an externalist theory. Even though there are significant physical differences between Tim and Tim*, mentally they are alike. Evidentialism implies that, since Tim and Tim* are mentally alike, they have the same evidence, and thus are justificationally alike as well. For example, they are both justified in believing that they have hands. This makes evidentialism an internalist theory. Reliabilism, on the other hand, allows that, even though Tim and Tim* are mentally alike, they differ justificationally, since Tim's beliefs are (by and large) produced by reliable cognitive faculties, whereas the faculties that produce Tim*'s beliefs may count as unreliable. For example, some versions of reliabilism imply that Tim is justified in believing that he has hands, whereas Tim* is not. This makes reliabilism an externalist theory.
2.4 Why Internalism?
Why think that justification is internal? One argument for the internality of justification goes as follows: "Justification is deontological: it is a matter of duty-fulfillment. But duty-fulfillment is internal. Therefore, justification is internal." Another argument appeals to the brain-in-the-vat scenario we considered above: "Tim*'s belief that he has hands is justified in the way that Tim's is justifed. Tim* is internally the same as Tim and externally quite different. Therefore, internal factors are what justify beliefs." Finally, since justification resulting from the possession of evidence is internal justification, internalism can be supported by way of making a case for evidentialism. What, then, can be said in support of evidentialism? Evidentialists would appeal to cases in which a belief is reliably formed but not accompanied by any experiences that would qualify as evidence. They would say that it's not plausible to claim that, in cases like that, the subject's belief is justified. Hence such cases show, according to evidentialists, that a belief can't be justified unless it's supported by evidence.
2.5 Why Externalism?
Why think that justification is external? To begin with, externalists about justification would point to the fact that animals and small children have knowledge and thus have justified beliefs. But their beliefs can't be justified in the way evidentialists conceive of justification. Therefore, we must conclude that the justification their beliefs enjoy is external: resulting not from the possession of evidence but from origination in reliable processes. And second, externalists would say that what we want from justification is the kind of objective probability needed for knowledge, and only external conditions on justification imply this probability. So justification has external conditions.
3. The Structure of Knowledge and Justification
The debate over the structure of knowledge and justification is primarily one among those who hold that knowledge requires justification. From this point of view, the structure of knowledge derives from the structure of justification. We will, therefore, focus on the latter.
According to foundationalism, our justified beliefs are structured like a building: they are divided into a foundation and a superstructure, the latter resting upon the former. Beliefs belonging to the foundation are basic. Beliefs belonging to the superstructure are nonbasic and receive justification from the justified beliefs in the foundation.
For a foundationalist account of justification to be plausible, it must solve two problems. First, by virtue of exactly what are basic beliefs justified? Second, how do basic beliefs justify nonbasic beliefs? Before we address these questions, let us first consider the question of what it is that makes a justified belief basic in the first place. Once we have done that, we can then move on to discuss by virtue of what a basic belief might be justified, and how such a belief might justify a nonbasic belief.
According to one approach, what makes a justified belief basic is that it doesn't receive its justification from any other beliefs. The following definition captures this thought:
Doxastic Basicality (DB)
S's justified belief that p is basic if and only if S's belief that p is justified without owing its justification to any of S's other beliefs.
Let's consider what would, according to DB, qualify as an example of a basic belief. Suppose you notice (for whatever reason) someone's hat, and you also notice that that hat looks blue to you. So you believe
(B) It appears to me that that hat is blue.
Unless something very strange is going on, (B) is an example of a justified belief. DB tells us that (B) is basic if and only if it does not owe its justification to any other beliefs of yours. So if (B) is indeed basic, there might be some item or other to which (B) owes its justification, but that item would not be another belief of yours. We call this kind of basicality ‘doxastic’ because it makes basicality a function of how your doxastic system (your belief system) is structured.
Let us turn to the question of where the justification that attaches to (B) might come from, if we think of basicality as defined by DB. Note that DB merely tells us how (B) is not justified. It says nothing about how (B) is justified. DB, therefore, does not answer that question. What we need, in addition to DB, is an account of what it is that justifies a belief such as (B). According to one strand of foundationalist thought, (B) is justified because it can't be false, doubted, or corrected by others. So (B) is justified because (B) carries with it an epistemic privilege such as infallibility, indubitability, or incorrigibility. The idea is that (B) is justified by virtue of its intrinsic nature, which makes it possess some kind of an epistemic privilege.
Note that (B) is not a belief about the hat. Rather, it's a belief about how the hat appears to you. So (B) is an introspective belief about a perceptual experience of yours. According to the thought we are considering here, a subject's basic beliefs are made up of introspective beliefs about the subject's own mental states, of which perceptual experiences make up one subset. Other mental states about which a subject can have basic beliefs include such things as having a headache, being tired, feeling pleasure, or having a desire for a cup of coffee. Beliefs about external objects do not and indeed cannot qualify as basic, for it is impossible for such beliefs to own the kind of epistemic privilege needed for the status of being basic.
According to a different version of foundationalism, (B) is justified not by virtue of possessing some kind of privileged status, but by some further mental state of yours. That mental state, however, is not a further belief of yours. Rather, it is the very perceptual experience that (B) is about: the hat's looking blue to you. Let ‘(E)’ represent that experience. According to this alternative proposal, (B) and (E) are distinct mental states. The idea is that what justifies (B) is (E). Since (E) is an experience, not a belief of yours, (B) is, according to DB, basic.
Let's call the two versions of foundationalism we have distinguished privilege foundationalism and experiential foundationalism. Privilege foundationalism restricts basic beliefs to beliefs about one's own mental states. Experiential foundationalism is less restrictive. According to it, beliefs about external objects can be basic as well. Suppose instead of (B), you believe
(H) That hat is blue.
Unlike (B), (H) is about the hat itself, and not the way the hat appears to you. Such a belief is not one about which we are infallible or otherwise epistemically privileged. Privilege foundationalism would, therefore, classify (H) as nonbasic. It is, however, quite plausible to think that (E) justifies not only (B) but (H) as well. If (E) is indeed what justifies (H), and (H) does not receive any additional justification from any further beliefs of yours, then (H) qualifies, according to DB, as basic.
Experiential Foundationalism, then, combines to two crucial ideas: (i) when a justified belief is basic, its justification is not owed to any other belief; (ii) what in fact justifies basic beliefs are experiences.
Under ordinary circumstances, perceptual beliefs such as (H) are not based on any further beliefs about one's own perceptual experiences. It is unclear, therefore, how privilege foundationalism can account for the justification of ordinary perceptual beliefs like (H). Experiential foundationalism, on the other hand, has no trouble at all explaining how ordinary perceptual beliefs are justified: they are justified by the perceptual experiences that give rise to them. This could be viewed as a reason for preferring experiential foundationalism to privilege foundationalism.
Above, we noted that how to think of basicality is not uncontroversial. DB defines just one kind of basicality. Here's an alternative conception of it:
Epistemic Basicality (EB)
S's justified belief that p is basic if and only if S's justification for believing that p does not depend on any justification S possesses for believing a further proposition, q.
EB makes it more difficult for a belief to be basic than DB does. To see why, we turn to the chief question (let's call it the ‘J-question’) that advocates of experiential foundationalism face:
Why are perceptual experiences a source of justification?
One way of answering the J-question can be viewed as a compromise position, since it is meant to be a compromise between foundationalism and its competitor, coherentism. The compromise position will be of interest to us because it illustrates how DB and EB differ. For if we adopt the compromise position, beliefs such as (H) will qualify as basic according to DB, but according to EB as nonbasic. So let's see what the compromise position says.
From a coherentist point of view, we might answer the J-question as follows: Perceptual experiences are a source of justification because we are justified in believing them to be reliable. As we will see below, making perceptual justification dependent on the existence of reliability-attributing beliefs is quite problematic. There is, however, an alternative answer to the J-question that appeals to reliability without making perceptual justification dependent upon beliefs that attribute reliability to perceptual experiences. According to this second answer to the J-question, perceptual experiences are a source of justification because we have justification for taking them to be reliable. That's the view we shall call the compromise position.
Note that your having justification for believing that p doesn't entail that you actually believe p. For example, if you believe that the person next to you wears a blue hat, you have justification for believing that the person next to you wears a blue hat or a red hat. But of course you are unlikely to believe the latter even though you have justification for it. Likewise, your having justification for attributing reliability to your perceptual experiences doesn't entail that you have given thought to the matter and actually formed the belief that they are reliable. According to the kind of coherentism we considered above, if your perceptual experiences are a source of justification for you, it must be the case that you have considered the matter and believe them to be reliable. The compromise position says no such thing. It says merely that, if your perceptual experiences are a source of justification for you, you must have justification for believing them to be reliable.
What might give us justification for thinking that our perceptual experiences are reliable? That's a complicated issue. For our present purposes, let's consider the following answer: We remember that they have served us well in the past. We are supposing, then, that justification for attributing reliability to your perceptual experiences consists of memories of perceptual success. According to the compromise position, it is never a perceptual experience (E) by itself that justifies a perceptual belief, but only (E) in conjunction with suitable track-record memories that give you justification for considering (E) reliable. Let ‘(E)’ again stand for the hat's looking blue to you, and ‘(H)’ for your belief that that hat is blue. According to the compromise position, (E) justifies (H) only if (E) is accompanied by track-record memories (M) that give you justification for attributing reliability to your visual experiences. So what, according to the compromise position as we have described it, justifies (H) is the conjunction of (E) and (M).
We can now see how DB and EB differ. According to the compromise position, your having justification for (H) depends on your having justification for believing something else in addition to (H), namely that your visual experiences are reliable. As a result (H) is not basic in the sense defined by EB. However, (H) might still be basic in the sense defined by DB. As long as your justification for (H) is owed solely to (E) and (M), neither of which includes any beliefs, DB tells us that (H) is basic. It follows that an experiential foundationalist who wishes to do.