Online research in philosophy

The knowledge account of assertion—roughly: one should not assert what one does not know—aspires to identify the norm distinctive of assertion. One main argument given in support of the knowledge account has been the success with which it explains a variety of Moore-paradoxical assertion. But that explanation does not generalize satisfactorily.

Taking Per Martin-Löf’s constructive type theory as a starting-point a theory of assertion is developed, which is able to account for the epistemic aspects of the speech act of assertion, and in which it is shown that assertion is not a wide genus. From a constructivist point of view, one is entitled to assert, for example, that a proposition A is true, only if one has constructed a proof object a for A in an act of demonstration. One thereby has grounded the assertion by an act of demonstration, and a grounding account of assertion therefore suits constructive type theory. Because the act of demonstration in which such a proof object is constructed results in knowledge that A is true, the constructivist account of assertion has to ward off some of the criticism directed against knowledge accounts of assertion. It is especially the internal relation between a judgement being grounded and its being known that makes it possible to do so. The grounding account of assertion can be considered as a justification account of assertion, but it also differs from justification accounts recently proposed, namely in the treatment of selfless assertions, that is, assertions which are grounded, but are not accompanied by belief.

The Knowledge Account of Assertion (KAA) has received added support recently from data on prompting assertion (Turri 2010) and from a refinement suggesting that assertions ought to express knowledge (Turri 2011). This paper adds another argument from parenthetical positioning, and then argues that KAA’s unified explanation of some of the earliest data adduced in its favor recommends KAA over its rivals.

Many philosophers favour the simple knowledge account of assertion, which says you may assert something only if you know it. The simple account is true but importantly incomplete. I defend a more informative thesis, namely, that you may assert something only if your assertion expresses knowledge. I call this 'the express knowledge account of assertion', which I argue better handles a wider range of cases while at the same time explaining the simple knowledge account's appeal. §1 introduces some new data that a knowledge account of assertion well explains. §2 explains the simple knowledge account's advantage over two of its main competitors. §3 presents a problem for the simple account and offers a solution, which is to adopt the express knowledge account. §4 encapsulates the case for the express knowledge account, and offers a unifying vision for the epistemology of belief and assertion. §5 answers an objection. §6 briefly sums up. Even those who ultimately reject my conclusion can still benefit from the new data presented in §1, and learn an important lesson from the problem discussed in §3, which demonstrates a general constraint on an acceptable account of the norm of assertion.

A common view in the recent philosophical literature is that knowledge is the norm governing proper assertion. Thus, according to Keith DeRose, “…one is positioned well-enough to assert that P iff one knows that P” (DeRose 2002, p. 180). Let us call the thesis expressed here the Knowledge Norm of Assertion, or the KNA, and formulate it as follows.

According to the increasingly popular knowledge account, assertion is governed by the rule that speech acts of that kind require knowledge of their content. Timothy Williamson has argued that this knowledge rule is the constitutive rule of assertion. It is argued here that it is not the constitutive rule of assertion in any sense of the term, as it governs only some assertions rather than all of them. A (qualified) knowledge rule can in fact be derived from the traditional analysis of assertion according to which assertion is the linguistic expression of belief. Because it is more informative, this analysis provides a better point of departure for defending the knowledge account than Williamson’s view according to which the knowledge rule is part of the analysis of assertion.

Keith DeRose has recently argued that the contextual variability of appropriate assertion, together with the knowledge account of assertion, yields a direct argument that ’knows’ is semantically contextsensitive. The argument fails because of an equivocation on the notion of warranted assertability. Once the equivocation is removed, it can be seen that the invariantist can retain the knowledge account of assertion and explain the contextual variability of appropriate assertion by appealing to Williamson’s suggestion that practical and conversational considerations can influence the extent to which adherence to the constitutive norm of assertion matters.

I am currently examining the suggestion that assertion and practical reasoning are subject to specifically epistemic norms, and the consequences of this suggestion for the correct account of knowledge. One currently popular view is that knowledge is the epistemic norm of both assertion and practical reasoning (see DeRose, Hawthorne, Stanley and Williamson). If assertion and practical reasoning are governed by the knowledge norm, then one criterion for an account of knowledge is that it should respect the ties between knowledge, assertion and practical reasoning. In this way, the knowledge norm is at the heart of contemporary debate about the correct account of knowledge, e.g. the debate between contextualism and invariantism (see Hawthorne.

The knowledge account of assertion (KAA) is the view that assertion is governed by the norm that the speaker should know what s/he asserts. It is not the purpose of this article to examine all the criticisms nor to try to give a full defence of KAA, but only to defend it against the charge of being normatively incorrect. It has been objected that assertion is governed by other norms than knowledge, or by no norm at all. It seems to me, however, that a number of these criticisms are based on a number of misunderstandings of the notion of a norm and of the way it can regulated a given practice. Once we spell out in what sense knowledge can play a normative role in this context, the KAA appears much more plausible.

What is the normative role of knowledge? I argue that knowledge plays an important role as a norm of assertion and action, which is explained and unified by its more fundamental role as a norm of belief. Moreover, I propose a distinctive account of what this normative role consists in. I argue that knowledge is the aim of belief, which sets a normative standard of correctness and a corresponding normative standard of justification. According to my proposal, it is correct to believe, assert and act on a proposition if and only if one is in a position to know it, but one has justification to believe, assert and act on a proposition if and only if one has justification to believe that one is in a position to know it.