Internalism versus Externalism

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Internalism in epistemology is a thesis about the nature of epistemic normativity, or the sort of normativity that is involved in the evaluation of cognition. Specifically, internalists claim that the (epistemically) normative status of a belief is entirely determined by factors that are relevantly "internal" to the believer's perspective on things. By contrast, externalists in epistemology deny this. The externalist says that the epistemic status of a belief is not entirely determined by factors that are internal to the believer's perspective.

When internalism and externalism are characterized in this way, several things become apparent. First, internalism is a rather strong thesis, in the sense that it says that epistemic status is entirely a function of internal factors. By contrast, the denial of internalism is a relatively weak thesis. Externalism in epistemology holds that some factors that are relevant to epistemic status are not internal to the believer's perspective. A second point to note is that there are several kinds of epistemically normative status, corresponding to several kinds of epistemic evaluation. We can say that a belief is justified, rational, reasonable, or intellectually responsible, and these need not mean the same thing. It is possible, then, to be an internalist about some kinds of epistemic status and an externalist about others. Hence, there are a variety of internalisms and a corresponding variety of externalisms.

Third, we get different understandings of internalism (and externalism) depending on different ways that we may understand the phrase "internal to the believer's perspective." The most common way to understand the phrase is that something is internal to a believer's perspective just in case the person has some sort of privileged access to the thing in question. For example, some fact F is relevantly internal to some person S's perspective if S can know by reflection alone whether F obtains. A related, though not equivalent, understanding of "internal to S's perspective" is as follows: Some factor F is internal to S's perspective just in case F constitutes part of S's mental life. For example, a person's perceptual experience counts as internal on this understanding, since how things appear perceptually to S is part of S's mental life in the relevant sense. Also, any belief or representation that S has about how things are would be internal on this understanding, since one's beliefs and other representations are also part of one's mental life. These two understandings are related because it is plausible to think that one has privileged access to what goes on in one's mental life, and perhaps only to what goes on in one's mental life. In that case the two understandings would amount to the same thing for practical purposes. Internalism would then be the thesis that epistemic status (of some specified sort) is entirely a function of factors that are part of one's mental life, and to which one therefore has privileged access.

Finally, it is apparent that some varieties of internalism are initially more plausible than others. That is, some sorts of epistemic evaluation are obviously externalist on the previous understandings. Most importantly, and perhaps most obviously, whether a belief counts as knowledge is an external matter, if only because a belief counts as knowledge only if it is true, and whether a belief is true is typically an external matter.

Objective versus Subjective Evaluations

There is another reason knowledge and many other sorts of epistemic evaluation must be understood as externalist, however. Consider that we can evaluate both persons and their beliefs in two different ways. Broadly speaking, we can evaluate them either from an objective point of view or from a subjective point of view. From the objective point of view we can ask whether there is a good fit between the person's cognitive powers and the world. For example, we can ask whether the person has a good memory or an accurate vision. Also from this point of view we can ask whether a person's methods of investigation are reliable, in the sense that they are likely to produce accurate results. By contrast, there is a second broad category of epistemic evaluation. This sort does not concern whether a belief is objectively well formed, but whether it is subjectively well formed. It asks not about objective fitness, but about subjective appropriateness. Internalism is pretty much a nonstarter with respect to evaluations of the first category. Evaluations from an objective point of view involve factors such as accuracy, reliability, and appropriate causal relations to one's environment, and these are paradigmatically external factors. Therefore, internalism is best understood as a thesis about the second broad category of epistemic evaluation: It is a thesis about what factors determine subjective appropriateness. Let us use the term epistemic justification to signify this second sort of epistemic status. In that case internalism is the thesis that epistemic justification is entirely a function of factors that are within the believer's perspective.

Three Considerations in Favor of Internalism

Why would someone be an internalist? Three considerations have been stressed in the literature. The first begins with an assumption about the nature of epistemic justification (where epistemic justification refers to the sort of subjective appropriateness required for knowledge or some other important epistemic status). The assumption is this: A belief is epistemically justified just in case it is epistemically responsible. However, the argument continues, epistemic responsibility is entirely a matter of factors that are internal to S's perspective. Therefore, epistemic justification is entirely a matter of factors that are internal to S's perspective.

A second consideration put forward in favor of internalism invokes a strong intuition about epistemic justification. Namely, in many cases it seems that believers who are alike in terms of internal perspective must also be alike in terms of epistemic justification. The point is often illustrated by considering René Descartes's victim of an evil deceiver. Suppose that the victim is exactly like you in terms of internal perspective. Even if the victim lacks knowledge, the argument goes, surely his beliefs are as well justified as yours are. If you are justified in believing that there is a table before you, and if the victim's perspective is exactly as yours, then he must be justified in believing that there is a table before him.

A third consideration invoked in favor of internalism is that externalism makes an answer to skepticism too easy. Philosophical problems are supposed to be difficult. If the externalist has an easy answer to the problem of skepticism, this argument goes, then that is good reason to think that externalism is false. At the least it is good reason to think that the externalist has changed the subjectthat he is no longer talking about our traditional notions of justification and knowledge.

How does externalism make an answer to skepticism too easy? The idea is roughly as follows: According to the skeptic one can know via sense perception only if one knows that sense perception is reliable. Similarly, one can know by inductive reasoning only if one knows that inductive reasoning is reliable. This creates problems for the internalist, because it is hard to understand how one can mount a noncircular argument to the desired conclusions about the reliability of one's cognitive powers. There is, however, no such problem for the externalist since the externalist can deny the initial assumption of the skeptical argument. For example, an externalist can insist that sense perception gives rise to knowledge so long as sense perception is in fact reliable. There need be no requirement, on an externalist account, that one know that one's perception is reliable. What is more, on an externalist account one seemingly can know that one's cognitive powers are reliable, and easily so. For example, one can use reliable perception to check up on perception, and then reason from there that perception is reliable. Similarly, one can use reliable induction to check up on induction, and then reason from there that induction is reliable.

Externalist Replies

Externalists reply that none of these considerations adequately motivate internalism. First, externalists argue, even if epistemic justification is to be understood in terms of epistemic responsibility, it is false that epistemic responsibility is entirely a matter of factors that are internal to S's perspective. This is because whether a belief is epistemically responsible is partly a function of the belief's etiology, or how S came to have the belief in the first place. For example, whether a person is epistemically responsible in holding some belief is partly a function of the person's prior behavior: If S's reasons for believing b are the result of prior negligence, then S is not now blameless in believing b. Similarly, we can make a distinction between (1) merely having good reasons for a belief, and (2) believing on the basis of those reasons. Plausibly, a belief is epistemically praiseworthy only if it is believed on the basis of good reasonsmerely having good reasons, if one does not use them, is not enough. But etiological considerations such as these involve external factors; that is, factors that are not typically internal to S's perspective.

The same line of argument has been used to counter the second consideration in favor of internalism. The problem is that two believers might be alike internally, and yet different regarding the causal genesis of their beliefs. Suppose that two persons arrive at the same internal perspective, but that one does so in a way that is epistemically responsible, whereas the other does so in a way that is careless and thick-headed. The two persons will not be alike in epistemic justification, although they share the same internal perspective.

Finally, externalists argue that the third consideration in favor of internalism is self-defeating. In effect, internalists claim that only they can give a satisfactory answer to traditional skeptical concerns. On the contrary, externalists argue, internalism makes it impossible to answer the skeptic. This is because traditional skeptical arguments assume internalism about epistemic justification. Moreover, if one concedes that assumption, externalists argue, then the skeptic has all he or she needs to construct skeptical arguments that are otherwise sound. Therefore, externalists conclude, internalism about epistemic justification guarantees skepticism about epistemic justification.

See also Epistemology.


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John Greco (1996, 2005)

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Internalism versus Externalism

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Internalism versus Externalism