According to many philosophers, assertions are partially governed by an epistemic norm, at least in the minimal sense that they must satisfy a relevant epistemic condition.¹ But what is this epistemic condition? The main proposals include truth (Weiner 2005; Whiting 2013), belief (Bach 2005), knowledge (Williamson 2000; DeRose 2009; Ichikawa 2017), reasonableness or justification to believe (Douven 2006; Lackey 2007; Kvanvig 2009), and warrant (Brown 2010, 2011; Gerken 2017). Many writers are monist, but some defend pluralism (Levin 2008). Some take the relevant epistemic condition to be in some way sensitive to the context (DeRose 2009; Brown 2010, 2011; Gerken 2017; Ichikawa 2017) while others contend that it is invariant or insensitive.

In this paper, my aim is to introduce and defend a view similar to that of Stanley (2008), according to which the relevant epistemic condition is epistemic certainty, where “certainty” is understood in a context-sensitive way. In section 1, I introduce the certainty view by clarifying the relations between epistemic certainty, subjective certainty and knowledge. I explain why I think it is epistemic certainty, rather than subjective certainty, which primarily matters for assertion. In section 2, I show that, in contrast to “know,” there are strong linguistic and conversational reasons to think that “certain” is context-sensitive. In section 3, I respond to Pritchard’s worry that the proposed account is too strong to accommodate our current practice of assertion. Section 4 shows that the certainty view easily explains all the conversational and linguistic data recently put forth in favour of the knowledge view, while also explaining data recalcitrant to the knowledge view. Finally, I adduce two principled considerations in favour of the certainty view in section 5.^{2, 3}

1 Epistemic Certainty, Subjective Certainty, and Knowledge

According to the proposal defended in this paper, the epistemic condition relevant for appropriate assertion is epistemic certainty:

Some basic clarifications are required in order to get the proposal right. First, we can think of epistemic certainty as a high degree of epistemic justification (many would say the highest degree) and of subjective certainty as a high degree of confidence (many would say the highest degree). Second, in ordinary and philosophical contexts, we often use the expression “S is certain/sure that \(p\)” to refer to subjective certainty. But while we mainly use “It is certain for S that \(p\)” to refer to epistemic certainty in philosophical contexts, this expression is not frequently used in ordinary contexts.⁴ However, the notion of epistemic certainty is not technical. Suppose there is a televised poker tournament where the broadcasters and audience can see the hands but the players cannot. One player bets confidently at a point when it is not certain, given the information available to her, that her hand is the best, though the broadcasters and audience can see that it is. It seems perfectly natural to say something like “She can’t be sure that her hand is the best” or “She should not be so sure that her hand is the best.” These are statements about lack of epistemic warrant for subjective certainty, i.e about lack of epistemic certainty.

A third clarification concerns the relation between knowledge and epistemic certainty. It’s natural to think that epistemic certainty entails knowledge-level justification (or being in a position to know). Perhaps more surprisingly, the view defended in this paper also takes it that knowledge or knowledge-level justification does not entail epistemic certainty.⁵ At first sight, this seems to clash with infallibilist approaches to knowledge. On closer inspection, however, it should be clear that, on pain of scepticism, everyone should grant that knowledge does not require satisfying absolutely maximal epistemic standards (e.g. Cartesian certainty).⁶ In addition, and following for example Williamson’s influential non-sceptical infallibilist view, it’s natural to think that there is some epistemic space between knowledge-level standards and absolutely maximal epistemic standards.⁷ This fact is reflected in ordinary language. The expression “I know that \(p\) with certainty (/for sure)” does not appear redundant and expresses something stronger than “I know that \(p\)” (although not necessarily something as strong as the satisfaction of Cartesian standards). Thus, the ordinary notion of certainty seems to capture a degree of justification (or confidence) between knowledge-level justification (or confidence) and absolutely maximal certainty. This notion of certainty is the notion invoked by the view defended in this paper.

Let me add two further clarifications. In section 4 below, we will see that expressions of subjective certainty and uncertainty are also highly relevant for assertions. On this basis, one might think that what really matters is subjective certainty:⁸

Further, I will take the data concerning subjective certainty as favouring CN-E and not CN-S. This may seem problematic.

Some reflection on the relation between epistemic and subjective certainty can dispel these worries, though. To begin with, a natural thought is that epistemic certainty is the epistemic norm of subjective certainty:⁹

If so, if we accept either CN-E or CN-S, there will be something inappropriate if a subject asserts that \(p\) while lacking epistemic certainty or subjective certainty (see Stanley 2008, 51–52). Indeed, suppose we accept CN-E and suppose that S asserts that \(p\) while lacking epistemic certainty. It follows that S violates the supposed norm of assertion (CN-E). Assume that S asserts that \(p\) while lacking subjective certainty. S violates either the norm of subjective certainty (ECNSC) or the supposed norm of assertion (CN-E). Alternatively, suppose we accept CN-S. If S asserts that \(p\) while lacking epistemic certainty, then S violates either the norm of subjective certainty (ECNSC) or the supposed norm of assertion (CN-S). If S asserts that \(p\) while lacking subjective certainty, then S violates the supposed norm of assertion (CN-S). In brief, given ECNSC and the subject’s adherence to either CN-E or CN-S, if it’s appropriate for S to assert that \(p\), then S does not lack epistemic and subjective certainty with respect to \(p\).

Still, why should we prefer CN-E over CN-S? The main reason is the following. Suppose the norm of assertion is CN-S. It follows that if, after reading his favoured guru’s book, John is certain or completely convinced that he is a cabbage, then John can appropriately assert “I am a cabbage.” But it is far from clear, to say the least, that John’s assertion is epistemically warranted. Further, in general, we should not allow normative reasons (and permissions) to be generated merely by the adoption of unjustified attitudes. This point has been largely and forcefully made in the literature with regard to normative requirements in general and there is no reason to think that similar considerations do not apply here.¹⁰ Yet, according to CN-S, if John wants to assert that he is a cabbage while he is not certain that he is a cabbage, he can warrant his assertion by adopting the attitude of certainty. CN-S has implausible consequences.¹¹ It’s important to stress, though, that in this framework the apparent plausibility of CN-S can be explained: necessarily, if S satisfies ECNSC and CN-E, then either S is subjectively certain or she does not assert. But, again, that does not imply that there is a norm of assertion such as CN-S.

2 The Context-Sensitivity of Epistemic Certainty

An additional claim essential to the proposed view is that “certain” is context-sensitive. To illustrate, consider the following cases (inspired by Huemer 2007):

A visual experience that \(p\) seems to be sufficient for an appropriate assertion of “It is certain that \(p\)” in airport, but insufficient for an appropriate assertion of “It is certain that \(p\)” in epistemology class. This suggests that the epistemic standards that must be satisfied for the truth of sentences such as “It is certain that \(p\)” and “It is uncertain that \(p\)” shift with the context (i.e. the aim of the discussion, the interests of the speakers, etc.).¹²

Similar pairs of cases were initially offered in favour of contextualism about “know.”¹³ However, a potential problem for contextualism about “know” is that, prima facie, there are no clear linguistic reasons to think that “know” is context-sensitive and some linguistic reasons to think otherwise.¹⁴ In addition, we seem to be ignorant of the alleged context-relativity of “know” whereas we are not ignorant of the context-sensitivity of other uncontroversial context-sensitive terms, like indexicals, gradable adjectives, etc (see Schiffer 1996). Crucially, things are radically different with “certain.” From a linguistic point of view, it is highly plausible that “certain” is context-sensitive. For it is uncontroversial that “certain” (contrary to “know,” and like “tall”) is gradable. It can take the comparative form (more… than…), it can be modified by degree modifiers such as adverbs (very, extremely, totally, absolutely…), and it can be combined with “how” to form questions. We can say that John is more certain than Bill that the bank is open, that John is absolutely certain that the bank is open, and we may ask how certain John is. (Similar examples can be provided involving an epistemic sense of “certain.”) If so, there is a scale associated with this adjective. Like “tall,” it’s very plausible to think that the degree on the scale which picks out the appropriate threshold for “certain” is context-sensitive.

Someone may object that “certain” is an absolute maximum-standard gradable adjective, which always picks out the highest degree on the scale.¹⁵ Even so, recent linguistic theories have suggested that absolute adjectives may also be context-sensitive (what counts as “the highest degree” on the scale may be context-sensitive).¹⁶ Further, it’s common (and useful) to distinguish a relative (or non absolutely maximal) sense of “certain” from an absolute sense of “certain,” so that we can distinguish “certainty” from “absolute certainty,” and various degrees of certainty in between.¹⁷ For example, it does not seem weird at all to say “I’m sure that I have hands, but I am even more certain that I exist.” This makes sense of the idea that non-sceptical infallibilists about knowledge can grant that we can know that \(p\) with “more or less certainty,” where “less certainty” does not imply that the proposition is uncertain or that we are not certain of it in some important sense.¹⁸ Thus, even if “absolute certainty” were not context-sensitive, it remains that the threshold for “certain” could be context-sensitive. In contrast to “know,” there is no linguistic objection to the idea that “certain” (or “absolutely certain”) is context-sensitive and some good reasons to think that it is.

It is also important to emphasize that we are not ignorant of the context-sensitivity of “certain.” Consider the following dialogue:

Clearly, John’s last answer is perfectly understandable, for “tall” is context-sensitive.

Consider now the following dialogue, with “know”:

John’s last utterance is rather puzzling and this is easily explained if “know” is not context-sensitive (see Stanley 2005, 52–53). John should either grant that he does not know, or else challenge the relevance of the traffic jam possibility.

Consider now a similar dialogue with “certain”:

John’s last answer is much less puzzling than John’s last answer in traffic jam 1, and as acceptable as that of John in tall.¹⁹ The claim that “certain” is context-sensitive, like “tall,” is immensely plausible—certainly much more plausible than the claim that “know” is context-sensitive.

In sum, linguistic and conversational considerations give us good reasons to adopt a context-sensitive view of “certain,” and if we adopt a shifty view at all, it’s much more natural to adopt a shifty view about “certain” than about “know.”

If “certain” is context-sensitive, we must determine the context which is relevant to assess the epistemic appropriateness of assertions. For this purpose, it seems quite natural to invoke the speaker’s context and relativise the certainty norm of assertion as follows:

With this relativised formulation in mind, we are now in a position to assess the main objection to the proposed view, namely, that it is too demanding to accommodate our current practice of assertion.

3 Pritchard’s Worry

The certainty view of assertion does not have many advocates nowadays. It is often thought that this view is too demanding.²¹ In particular, following Pritchard (2008), we might worry that the epistemic standards of “certain” cannot be sufficiently low to accommodate our current practice of assertion. More precisely, according to Pritchard (2008, 60), “prima facie at any rate, one would expect that the threshold for ‘certain’ should be fairly high in all contexts.” If so, we have some reason to expect that these standards will not be met often enough to warrant most of our assertions. However, while we can agree that the (contextually-influenced) standards of absolute certainty should be fairly high in all contexts, we must distinguish certainty and absolute certainty. Further, even if we grant that the threshold for “certain” should be at least as strong as knowledge-level justification in all contexts and stronger at least in some contexts, we need not assume that the epistemic standards for knowledge are particularly high. On some accounts, they are even as weak as a true belief.²² If the standards for knowledge are that weak, standards stronger than knowledge-level standards need not be that high. Of course, the weaker the knowledge-level standards are supposed to be, the less plausible is the thought that knowledge is (in many or some contexts) sufficient for certainty. But then, the more plausible is the thought that certainty does not demand very high standards. Conversely, the higher the knowledge-level standards are supposed to be, the more plausible is the claim that in many contexts they are sufficient for certainty, so that in many contexts certainty can be reached.

In addition, it’s natural to assume that knowledge is the “floor” of certainty, so that in low-standards contexts “S has knowledge-level justification for \(p\) if and only if \(p\) is certain for S” is true, and that these low-standards contexts are fairly frequent. This assumption explains why we might be naturally inclined to think that knowledge entails certainty. If this assumption is correct, indeed, in many contexts it would be false to say “S knows that \(p\) but S is not certain that \(p\) (/\(p\) is not certain).” We can combine this natural assumption with the consideration that, with regard to many propositions, our epistemic position is stronger than knowledge-level. For many propositions, we have testimonies coming from various sources, repeated visual and tactile experiences, knowledge that we know the relevant proposition, etc.²³ It follows that even if we grant that certainty requires fairly high standards in all contexts, this is not a compelling reason to think that certainty is not often reached.

Pritchard (2008, 60–61) also proposes the following case:

According to Pritchard, “it is hard to see why Jenny (or anyone else for that matter) would regard her as being certain of what she believes, whether the certainty in question is of the subjective or epistemic variety.” Thus, champions of the certainty view would encounter the following dilemma: either they must say that Jenny herself cannot appropriately flat-out assert the relevant proposition about the direction which, according to Pritchard, would contradict our intuitions and amount to conceding that “far more of our assertions are improper than we typically suppose” (2008, 61); or else they must grant that Jenny’s assertion would be appropriate, and the standards of certainty met, which is implausible, for “no-one would surely describe Jenny as certain of what she knows” (2008, 61).

Let me start with the second horn of the dilemma. Why can’t we see Jenny or the relevant proposition as certain in this context? Jenny is described as promptly acting on what she has been told, which suggests that she acts unhesitatingly, and therefore that she is in some sense certain in this context. Further, the person who communicates the information to Jenny is supposed to be knowledgeable about the area. On this basis, we may think that what she says is certain. For example, were Jenny to raise a doubt by asking, “But is it certain?”, it would seem perfectly appropriate for this person to reply, “Yes it is! I’ve been living here for 10 years!” All that Pritchard says in favour of the fact that Jenny is uncertain is that she has a low degree of confidence. But “low” is context-sensitive. We may think that, in Jenny’s context, this degree of belief counts as sufficiently high for certainty.

Consider the first horn of the dilemma. Suppose we accept that Jenny is uncertain and conclude that she herself cannot appropriately flat-out assert the proposition regarding the direction. First, contrary to what Pritchard suggests, this would not lead us to concede that much, for most of the propositions we assert in ordinary life are more warranted for us than this proposition is for Jenny. Second, it seems to me that if we suppose that Jenny is uncertain, the idea that her flat-out assertion would be inappropriate is rather intuitive, in particular if that supposition is fleshed out in more detail. Suppose, for example, that we say that Jenny is uncertain because she feels doubtful about the truth of the proposition or because she hesitates to act on it. Now, imagine that someone asks Jenny for the direction, and she unhesitatingly flat-out asserts the proposition in question. It seems that we should regard her flat-out assertion as inappropriate. We would expect her to hedge the assertion by saying something like, “This is the right direction, I believe.” Alternatively, it would be very natural for her to say, “I was told that this is the right direction.”

Lastly, it pays to note that the possible intuition that unconfident Jenny can warrantedly assert the target proposition can be explained by invoking the notion of conditional assertion. When we make assertions, we often speak loosely. We leave aspects of the asserted content implicit. In particular, as Bach (2010, 122–125) notes, many assertions seem to involve an implicit assumption of normality or an implicit ceteris paribus clause. For example, if unconfident Jenny asserts “This is the right direction,” we may argue that she asserts loosely and merely commits herself to the conditional “Provided things are normal (i.e. if what I’ve been told is true), this is the right direction.” Understood in this way, Jenny’s flat-out assertion does not constitute a counterexample to the certainty view of assertion.

Finally, Pritchard (2008, 63) notes that, “it is in fact very easy to get people to concede that they are not certain of something that they believe, even when no additional practical considerations are being raised.” If that is true, that is problematic for the certainty view, for the most plausible explanation why people easily concede that they are not certain is precisely that, in fact, they are not certain. Pritchard proposes the following case to support his claim:

According to Pritchard (2008, 63–64), “I would be unlikely to say ‘yes’.” I must say that I do not share Pritchard’s intuition here. At least, we should note that it is also far from clear that an ordinary subject (in a normal situation with low stakes) would be likely to say “no.” In contrast, it is clear that “Yes, I’m fairly/pretty/reasonably certain that the car is parked there” would be a very natural reply.²⁴ By using “fairly/pretty/reasonably certain” in this way, it does not seem that the subject retracts, qualifies or hedges his or her assertion (compare: “No, but I think/Probably it’s parked there”). Rather, in doing so the subject seems to maintain the assertion, which suggests that he or she thinks he or she satisfies the epistemic norm. If CN.R is true, that is what we should expect, for mentioning that we are reasonably certain (that is, certain although less than absolutely certain) indicates that we satisfy the certainty norm of assertion.

Perhaps the case is underdescribed. For example, it is unclear with what degree of clarity the subject is supposed to remember where he has parked the car or to what extent he has paid attention when he parked. Undoubtedly, there are cases where we are unsure, for example when we do not remember very well. But in many ordinary cases with low stakes, it appears to me that the most natural reply would be that we have no doubt or that we are certain enough. On this point, I can just encourage the reader to check whether people are willing to insist that they are (fairly) certain of where they have parked their car, what they have eaten at lunch, what job they have, where they live, etc.

4 Linguistic and Conversational Data

Let us now turn to the consideration of conversational and linguistic data. We can show that appealing to a certainty condition allows us to explain all the data put forth in favour of the knowledge account of assertion while also explaining data recalcitrant to this account.^{25, 26}

4.1 Moore’s Paradoxical Sentences

It is common to appeal to Moore’s paradoxical sentences to defend one or another view about the epistemic condition required for appropriate assertion. Moore (1942, 543) notes that it sounds incoherent to assert “\(p\) but I do not believe that \(p\).” Yet, it is clear that this sentence does not express a semantic contradiction, for it may well be true that \(p\) and that the subject who utters this sentence does not believe \(p\). So, how are we to explain the fact that asserting this sentence sounds incoherent?

A popular explanation appeals to the norm of assertion. Suppose, for example, that you should not assert what you do not believe. Suppose that you are seen as following this norm. Then, if you assert that \(p\), you are seen as believing that \(p\) (or at least as taking yourself to believe that \(p\)). In other words, in virtue of the supposed belief norm of assertion, by asserting that \(p\) you represent yourself as believing that \(p\). In the second half of your assertion, though, you say that you do not believe that \(p\). Thus, such an assertion sounds incoherent because it represents the assertor as believing and not believing that \(p\).

Consider the following sentences:

1. \(p\) but I do not believe that \(p\)

2. \(p\) but I do not know that \(p\)

3. \(p\) but I am not certain that \(p\)

4. \(p\) but it is not certain that \(p\)

Assertions of these sentences sound incoherent.²⁷

As Stanley notes, if we embrace the certainty view of assertion, we can easily explain in a unified way why assertions of (1)–(4) sound incoherent. Suppose you follow the certainty norm of assertion. When you assert that \(p\), you take \(p\) to be epistemically certain. Given the plausible bridge principle (ECNSC) according to which if \(p\) is epistemically certain for you, then you should be subjectively certain that \(p\) (at least if you consider whether \(p\)), if you assert that \(p\). Subjective certainty rightly based on epistemic certainty entails knowledge. So, when you assert that \(p\), you represent \(p\) as epistemically certain for you, and you represent yourself as believing with certainty that \(p\), and hence as knowing that \(p\). But when you assert the second half of sentences (1)–(4), you deny a necessary condition for epistemic and/or subjective certainty (namely, you deny that you believe that \(p\), that you know that \(p\), that \(p\) is certain, and that you are certain that \(p\)). You represent yourself as having incoherent attitudes.

4.2 Rejection of Two Explanations Consistent with the Knowledge Norm

Advocates of epistemic conditions weaker than certainty—such as knowledge—must propose a specific explanation for the infelicity of (3) and (4). A first explanation proposed by knowledge normers appeals to a supposed “contextual” connection between the epistemic standards of knowledge and those of certainty. When considering sentences similar to (3) and (4), Williamson (2000, 254) writes:

What seems to be at work here is a reluctance to allow the contextually set standards for knowledge and certainty to diverge. Many people are not very happy to say things like “She knew that A, but she could not be certain that A.”

According to this proposal, we can explain the infelicities of asserting (3) and (4) in the following way. By saying that \(p\), you represent yourself as knowing that \(p\) (assumption of the knowledge norm). In virtue of a general reluctance to dissociate the standards of knowledge from those of certainty, we expect you to be reluctant to say “I cannot be certain that \(p\),” for this would amount to representing yourself as endorsing

5. I know that \(p\) but I am not certain that \(p\) (/it is not certain that \(p\)).

Now, if we assume that knowledge is the norm of assertion and that we are reluctant to make assertions like (5), this may explain why we are reluctant to assert (3) or (4).

However, while it can be granted that an assertion of (5) sounds incoherent, Williamson’s explanation ultimately relies on the claim that people are reluctant to assert sentences like, “She knew that A, but she could not be certain that A.” But Williamson does not explain why people are so reluctant.²⁸

The main problem for Williamson’s approach, however, is that it is far from clear that we are reluctant to assert such sentences. As Stanley (2008) notes, asserting the following sentence does not sound incoherent:

6. S knows that \(p\), but being a cautious fellow, she is not certain that \(p\).²⁹

We may reinforce this line of thought by noting that assertions of the following sentence do not sound incoherent:

7. S knows that \(p\) but she does not know that she knows that \(p\). That’s why she is not certain that \(p\).³⁰

If we are not always reluctant to make third-person “knowledge” ascriptions while denying third-person certainty, it is hard to see how Williamson’s approach can explain the infelicity of (3), (4) and (5).

A second possible explanation of the infelicity of (3), (4) and (5) consistent with the knowledge norm for assertion could appeal to the distinction between warranted assertion and knowledge that the assertion is warranted, and to the claim that certainty is necessary for knowledge of knowledge.

The distinction between warranted assertion and knowledge that the assertion is warranted is sometimes used by proponents of the knowledge norm to explain why assertions of the following sentence sound infelicitous:

8. \(p\) but I do not know whether I know that \(p\).

According to proponents of the knowledge norm, indeed, knowledge that one knows is not required for epistemically appropriate assertion. So, as Sosa (2009) emphasizes, if they are right, why is it that asserting (8) sounds infelicitous?

In reply, advocates of the knowledge norm sometimes appeal to the thought that there is something bad in doing something appropriate without knowing that it is appropriate; and they say that an assertion of (8) sounds infelicitous because the subject represents herself as not knowing that the assertion is warranted (i.e. known), which is somehow wrong (see Benton 2013).

Now, suppose we understand certainty in terms of knowledge that one knows, as some writers suggest (e.g. Turri 2010, 459). The kind of explanation offered for the infelicity of (8) can be used by the knowledge normer to explain the infelicity of (3), (4) and (5). Someone asserting “\(p\) but I am not certain that \(p\) (/it is not certain that \(p\))” would represent herself as knowing that \(p\) (in virtue of the supposed knowledge norm of assertion), but as not knowing that she knows that \(p\). Hence, she would represent herself as not knowing that the assertion is warranted. And someone asserting “I know that \(p\) but I cannot be certain that \(p\)” would represent herself as being certain that she knows that \(p\) (in virtue of the knowledge norm of assertion), but as not being certain that \(p\). Hence the infelicity.

While interesting, there are several reasons to think that this explanation is ultimately unsuccessful. A first point to note is that it is far from clear that the problem with someone who asserts “\(p\)” while she cannot be certain that \(p\) has to do with the fact that she cannot know that she knows that \(p\). Indeed, asserting (9) seems equally infelicitous:

9. \(p\), but it is not certain that I know that \(p\).

Yet it may well be true that the subject knows that she knows that \(p\), without knowing that she knows that she knows that \(p\). But according to the proposal under examination, not knowing that one knows that one knows that \(p\) (or, in other words, not knowing that \(p\) is certain, or not being certain that one knows that \(p\)) should make no difference for an appropriate assertion that p, since what is required is merely warrant (i.e. knowledge) and knowledge that one has warrant (i.e. knowledge of knowledge that \(p\) or certainty that \(p\)).

Secondly, it is unclear that certainty is always necessary for knowing that one knows. Indeed, it seems that you can know that you know that \(p\) even if \(p\) is still uncertain. Suppose it is still uncertain that you know that you know that \(p\). Your epistemic position with respect to \(p\) could be better and, if so, we may think that \(p\) is not certain. More generally, if we think that knowledge does not entail certainty, it’s clear that you can know that you know that \(p\) even if \(p\) is not certain.

Thirdly, the proposal under examination crucially relies on the assumption that, in some sense, it is always bad to do something for which one has warrant if one does not know that one has warrant for doing it. Suppose that this assumption is true. It is then very plausible to think that the strength of the (alleged) requirement to know that one has warrant varies with the importance of being warranted.³¹ But if so, in contexts in which it is not at all important to make a warranted assertion, it should be possible to assert without obvious infelicity (3), (4), (5) and (8). Yet, assertions of these sentences always sound infelicitous.

In addition, it is hard to see why such a requirement should always be in force, in particular when it comes to epistemic warrant. Suppose that our epistemic position with respect to the target proposition is good enough for assertion, given the norm of assertion. Suppose that, for whatever general reason, a further relevant second-level epistemic position with respect to the first-level epistemic warrant is always required. Now, presumably, the same kind of reason should lead us to think that a relevant third-level epistemic position with respect to the second-level epistemic position is also always required. And so on. This obviously leads to an infinite regress. Since we have to stop somewhere, it is natural to stop at the first-level.

Fourthly, if the approach under examination is correct, it undermines a fundamental argument for the knowledge account. This argument is based on the fact that it is appropriate to challenge an assertion by using “know” (I consider this argument below). But if the present approach is correct, an advocate of a norm of truth, for example, could argue that when we require knowledge of the asserted proposition, we require knowledge that the assertion is warranted, i.e. we require that it is known that the assertion is true.³²

If these considerations are correct, there is little hope for the proponent of the knowledge norm in appealing to a distinction between warrant and knowledge of warrant. We cannot exclude that another proposal could be offered by the advocate of the knowledge norm or some other weaker condition. However, let me point out that, in contrast to rival views, the certainty view provides a unified and very straightforward explanation of the infelicity of asserting Moorean sentences.³³

4.3 Appropriate Challenges

In support of the knowledge account, Williamson (2000, 252–253) emphasizes that it is natural to challenge an assertion by asking “How do you know that \(p\)?” or “Do you know that \(p\)?” (see also Unger 1975, 263–264). Of course, these data suggest that knowledge is necessary, but they do not show that knowledge is sufficient. Therefore, they do not speak against the certainty view, for according to this view being in a position to know is necessary for certainty, and if you are in a position to know that \(p\) and you consider whether \(p\), you should know that \(p\). In addition, it’s crucial to note that we can challenge an assertion by invoking certainty (e.g. “Are your sure?”) (see Stanley 2008, 51). If knowledge is the norm of assertion, this is a surprising fact.

An explanation consistent with the knowledge account, relying on the claims that we ought to know that we have warrant and that certainty is necessary for knowledge of knowledge, is proposed by Turri (2010). However, to repeat, it’s far from clear that certainty that \(p\) is necessary for knowledge that one knows that \(p\). Second, it is hard to see why a requirement that one knows that one has epistemic warrant should always be in force. Third, this strategy undermines the argument for the knowledge norm based on the appropriateness of knowledge-based challenges.

Another suggestion would be that we must distinguish assertions and guarantees. This would explain why “certain” is used in some challenges. However, it seems that any kind of assertion can be properly challenged by using “certain” or “sure.” Further, asserting that \(p\) clearly seems to be a way of guaranteeing that \(p\). It would be very odd to say, “\(p\) but I do not guarantee that \(p\) is true.” Finally, if we still want to distinguish assertions and guarantees, given the distinction between certainty and absolute certainty, it seems more natural to associate guarantees with absolute certainty.

4.4 Unified Explanation of Moorean Sentences and Appropriate Challenges

Benton (2011) points out that a satisfying account of assertion should be able to explain in a unified way the Moorean data and the appropriateness of challenges. Indeed, appropriate challenges “can elicit a de facto Moorean paradox within a conversational context” (2011, 686). Consider:

Benton (2011, 686) argues that this favours the knowledge account because this account explains the relation between Moorean data and challenges in terms of knowledge.

However, the certainty view of assertion fares equally well in explaining why challenges in terms of knowledge may elicit de facto Moorean paradoxes. According to this view, the same thing explains why utterances of Moorean paradoxical sentences sound paradoxical and why we can challenge an assertion by using “know”: a necessary condition for an appropriate assertion that you know that \(p\) is that you are in a position to know that you are in a position to know that \(p\), and hence, by factivity of knowledge, that you are in a position to know that \(p\). If you are in a position to know that you know that \(p\) and you consider whether you know that \(p\), you should know that you know that \(p\), and by factivity of knowledge you should know that \(p\).

Further, it is not difficult to imagine a conversation with “certain” eliciting a de facto Moorean paradox in terms of certainty:

The certainty view has a simple and unified explanation for all these data, by appealing to the epistemic certainty norm for assertion (CN-E) and the epistemic certainty norm for subjective certainty (ECNSC), whereas the knowledge account does not.

4.5 Parenthetical Uses

Other linguistic data which have been produced have to do with parenthetical uses. First, consider parenthetical uses expressing the assertor’s mental state. When we want to express a mere belief in what we assert, we can use “believe” in a parenthetical position:

10. It is, I believe, raining.

11. It is raining, I believe.

As Benton (2011) notes, it is striking that we cannot (or do not) use “know” parenthetically in the same way. Consider:

12. It is, I know, raining

13. It is raining, I know.

This use of “know” in parenthetical position seems redundant. Benton argues that this constitutes a further argument in favour of the knowledge account. Indeed, on this account, in asserting that \(p\) you already represent yourself as knowing that \(p\). But if so, it is redundant to parenthetically use “know” to express your knowledge that \(p\) when you are already asserting that \(p\).

However, Benton fails to note that, like “know,” “certain” cannot be (or is not) used in this way without redundancy. Consider:

14. It is, it’s certain, raining

15. It is raining, it’s certain.

The certainty view of assertion can explain why these parenthetical uses of “certain” and “know” are redundant. The knowledge account of assertion merely explains why this use of “know” is redundant.

A possible worry is that one might think that if certainty is the norm of assertion, then, as knowledge is typically weaker than certainty, the parenthetical use of “know” should have the same effect as the parenthetical use of “believe” in hedging the assertion. However, the use of “know” in parenthetical position does not hedge the assertion. As Blaauw (2012) notes, it can even have a reinforcing effect. Consider the following case (see 2012, 106):

16. I am very lazy, I know!

What John says sounds natural, and he could also have said:

17. I am, I know, very lazy!

Of course, it is striking that the use of “believe” in parenthetical position does not have this reinforcing effect, but, rather, typically hedges the assertion. Blaauw takes these considerations to favour the knowledge account. If you already express your knowledge that \(p\) in asserting that \(p\), then by saying that you know that \(p\), you can reinforce what is already expressed. We might think that if certainty, rather than knowledge, is the epistemic norm of assertion, it is unclear why the parenthetical use of “know” can have this reinforcing effect whereas the parenthetical use of “believe” has a diminishing effect.

There is a reply, though. By asserting that you believe that \(p\), you represent as certain the proposition that you believe that \(p\), but you do not represent as certain the proposition that \(p\). Thus, you do not represent yourself as satisfying the epistemic norm for asserting \(p\), which is why the parenthetical use of “believe” can hedge the assertion. In contrast, by asserting that you know that \(p\), you represent as certain the proposition that you know that \(p\), and by factivity of knowledge, you represent as certain the proposition that \(p\). As a result, you represent yourself as satisfying the epistemic norm with respect to \(p\). This is why the parenthetical use of “know” does not hedge the assertion.

In sum, the set of data having to do with parenthetical uses are more easily explained by the certainty view than by the knowledge account.

4.6 Responses to Prompts to Assert

Benton (2020) notes that “a standard response when one feels not well-positioned to assert, in reply to a prompt like ‘Is it the case that \(p\)?’, is to answer ‘I don’t know’.” According to him, this speaks in favour of the knowledge account. Indeed, “the query was about \(p\), not about whether one knows that \(p\),” and thus the fact that it is appropriate to answer “I do not know that \(p\)” has to be explained. The knowledge account explains why this answer is appropriate: it is appropriate because it is appropriate to decline a prompt to assert by saying that one does not meet the epistemic norm for assertion.

Still, this line of argument also favours the certainty view of assertion. Suppose that \(p\) is not certain. A perfectly correct response to “\(p\)?” is “I’m not sure.” Further, note that the certainty view explains why “I do not know” is always an appropriate answer, because being in a position to know is a necessary condition for epistemic certainty. In contrast, the knowledge account cannot explain why “I’m not certain” is always an appropriate answer, since, according to this view, certainty is not required for assertion. As a consequence, considerations concerning typical ways of declining prompts to assert favour the certainty view over the knowledge account.

5 Two Principled Considerations

The certainty view of assertion appears to provide a straightforward and unified explanation of all the main linguistic and conversational data. To reinforce the case for this account, I shall now present two arguments based on principled considerations.

The first principled consideration is the following. It is hard to deny that the warrant required for appropriate assertion varies with the context (e.g. with the audience). Few would deny, for example, that in normal circumstances you can assert that \(p\) on the basis of a mere testimony that \(p\), whereas when it comes to testify that \(p\) before a court you should have first-hand knowledge. But assuming this variability, it is difficult to maintain the knowledge norm for assertion, while explaining the data involving “know,” without endorsing a shifty semantics about “know.”³⁴ Indeed, these data are invariant in the sense that, in all contexts, it’s infelicitous to say “\(p\) and I do not know that \(p\)”; in all contexts we can challenge an assertion by asking “How do you know that \(p\)?”; etc. Yet, as explained above, from a linguistic perspective it’s not prima facie plausible to think that “know” is context-sensitive. If we can propose an account compatible with an invariantist semantics for “know,” capable of explaining the invariant character of the data involving “know” and compatible with the claim that the epistemic warrant for assertion is variable, this account will certainly have an advantage. Therefore, it is an advantage of the certainty view that it respects the three following assumptions:

To illustrate, consider the knowledge account and the warrant account to see how they fail to respect these three assumptions. Assuming the knowledge norm, we can (partially) explain B. But if we embrace C we must reject A, for we assume that the epistemic standard of appropriate assertion is knowledge and that the epistemic standard of knowledge is invariant across contexts. If we accept A instead, we must then reject C. Suppose now that we adopt Gerken’s warrant account, according to which the warrant for epistemically appropriate assertion shifts with the context, in the sense that the warrant is sometimes weaker and sometimes stronger than knowledge-level warrant (see Gerken 2017). We can accept A and C, but it is unclear how to account for B. For example, in situations in which the warrant is supposed to be weaker than knowledge, we cannot appeal to the supposed norm to explain why it sounds infelicitous to assert “\(p\) but I do not know that \(p\).”³⁵

In contrast, consider the certainty view. We can adopt A, for the epistemic standard of certainty is taken to shift with the context. What degree of justification counts as good enough for certainty is partially influenced by the context. We can also respect B: the norm of assertion always requires at least knowledge-level justification and, given ECNSC, if you assert that \(p\), you consider whether \(p\), and you should be subjectively certain that \(p\). Therefore, you should know that \(p\). Finally, the certainty view respects the claim that the epistemic standards of knowledge are invariant across contexts.

The fact that claims A, B and C, which are independently plausible, are fully compatible with the certainty view, whereas together they raise problems for rival weaker accounts, provides a further argument for the certainty view. Of course, this argument is limited, for the claim that “certain” is context-sensitive could be disputed. However, given the considerations developed in section 2, it appears that it is highly plausible to think that “certain” is context-sensitive. In this regard, “certain” strongly differs from “know.”

The second principled consideration is that many philosophers find it plausible that knowledge does not entail (epistemic) certainty or the highest grade of justification. But if that is correct, first, we have to explain why asserting (5) sounds infelicitous:

As Stanley (2008) emphasizes, the certainty view provides a pragmatic explanation of the infelicity. Again, given the certainty norm of assertion, by asserting that you know that \(p\), you represent yourself as being certain that you know that \(p\), and by the factivity of knowledge, as being certain that \(p\). But this contradicts the second half of your assertion.³⁶

Second, if knowledge does not entail epistemic certainty or the highest grade of justification, it is obscure why knowledge is bound to always be sufficient for appropriate assertion. If knowledge does not require certainty or the highest grade of justification then, in principle, a situation can arise where the difference between knowledge and certainty could matter for appropriate assertion. In the absence of reasons to think that knowledge is bound to always be sufficient, it is more natural to think that certainty, rather than knowledge, is always sufficient for assertion.³⁷

In sum, it is plausible that the degree of justification required for warranted assertions shifts across contexts and that knowledge does not entail certainty. These two claims fit nicely with the certainty view of assertion whereas they are in tension with (many) rival weaker accounts.

6 Conclusion

The claim that certainty is the norm of assertion is often dismissed as implausible. In this paper, I’ve responded to the main objection that this view is too strong. I’ve also considered the main conversational and linguistic data advanced in the recent literature, and I have shown that the certainty view provides us with a straightforward and unified explanation of them. I have also argued that this account fits nicely with the plausible claims that the degree of justification required for appropriate assertion is variable and that knowledge does not entail certainty. I thereby hope to have shown that, on more careful reflection, the certainty account of assertion is a viable and respectable account.