Famously, the Church–Fitch paradox of knowability is a deductive argument from the thesis that all truths are knowable to the conclusion that all truths are known. In this argument, knowability is analyzed in terms of having the possibility to know. Several philosophers have objected to this analysis, because it turns knowability into a nonfactive notion. In addition, they claim that, if the knowability thesis is reformulated with the help of factive concepts of knowability, then (...) omniscience can be avoided. In this article we will look closer at two proposals along these lines :557–568, 1985; Fuhrmann in Synthese 191:1627–1648, 2014a), because there are formal models available for each. It will be argued that, even though the problem of omniscience can be averted, the problem of possible or potential omniscience cannot: there is an accessible state at which all truths are known. Furthermore, it will be argued that possible or potential omniscience is a price that is too high to pay. Others who have proposed to solve the paradox with the help of a factive concept of knowability should take note :53–73, 2010; Spencer in Mind 126:466–497, 2017). (shrink)

This paper shows that the knowability paradox isn’t a paradox because the derivation of the paradox is faulty. This is explained by showing that the K operator employed in generating the paradox is used equivocally and when the equivocation is eliminated the derivation fails.

Antirealists who hold the knowability thesis, namely that all truths are knowable, have been put on the defensive by the Church-Fitch paradox of knowability. Rejecting the non-factivity of the concept of knowability used in that paradox, Edgington has adopted a factive notion of knowability, according to which only actual truths are knowable. She has used this new notion to reformulate the knowability thesis. The result has been argued to be immune against the Church-Fitch paradox, (...) but it has encountered several other triviality objections. Schlöder in a forthcoming paper defends the general approach taken by Edgington, but amends it to save it in turn from the triviality objections. In this paper I will argue, first, that Schlöder's justification for the factivity of his version of the concept of knowability is vulnerable to criticism, but I will also offer an improved justification that is in the same spirit as his. To the extent that some philosophers are right about our intuitive concept of knowability being a factive one, it is important to explore factive concepts of knowability that are made formally precise. I will subsequently argue that Schlöder's version of the knowability thesis overgenerates knowledge or, in other words, it leads to attributions of knowledge where there is ignorance. This fits a general pattern for the research programme initiated by Edgington. This paper also contains preliminary investigations into the internal and logical structure of lines of inquiries, which raise interesting research questions. (shrink)

It has been argued that epistemic contextualism faces the so-called factivity problem and hence cannot be stated properly. The basic idea behind this charge is that contextualists supposedly have to say, on the one hand, that knowledge ascribing sentences like “S knows that S has hands” are true when used in ordinary contexts while, on the other hand, they are not true by the standard of their own context. In my paper, I want to show that the argument to the (...) factivity problem fails because it rests on the mistaken premise that contextualists are committed to the truth of particular ordinary knowledge attributions. (shrink)

Fitch’s Paradox shows that if every truth is knowable, then every truth is known. Standard diagnoses identify the factivity/negative infallibility of the knowledge operator and Moorean contradictions as the root source of the result. This paper generalises Fitch’s result to show that such diagnoses are mistaken. In place of factivity/negative infallibility, the weaker assumption of any ‘level-bridging principle’ suffices. A consequence is that the result holds for some logics in which the “Moorean contradiction” commonly thought to underlie the result is (...) in fact consistent. This generalised result improves on the current understanding of Fitch’s result and widens the range of modalities of philosophical interest to which the result might be fruitfully applied. Along the way, we also consider a semantic explanation for Fitch’s result which answers a challenge raised by Kvanvig. (shrink)

This paper addresses the question whether future contingents are knowable, that is, whether one can know that things will go a certain way even though it is possible that things will not go that way. First I will consider a long-established view that implies a negative answer, and draw attention to some endemic problems that affect its credibility. Then I will sketch an alternative line of thought that prompts a positive answer: future contingents are knowable, although our epistemic access of (...) them is limited in some important respects. (shrink)

Suppose for reductio that I know a proposition of the form <p and I don’t know p>. Then by the factivity of knowledge and the distribution of knowledge over conjunction, I both know and do not know p ; which is impossible. Propositions of the form <p and I don’t know p> are therefore unknowable. Their particular kind of unknowability has been widely discussed and applied to such issues as the realism debate. It hasn’t been much applied to theories of (...) the nature of knowledge. That is what I’m going to do here. (shrink)

In this paper I consider two paradoxes that arise in connection with the concept of demonstrability, or absolute provability. I assume—for the sake of the argument—that there is an intuitive notion of demonstrability, which should not be conflated with the concept of formal deducibility in a (formal) system or the relativized concept of provability from certain axioms. Demonstrability is an epistemic concept: the rough idea is that a sentence is demonstrable if it is provable from knowable basic (“self-evident”) premises by (...) means of simple logical steps. A statement that is demonstrable is also knowable and a statement that is actually demonstrated is known to be true. By casting doubt upon apparently central principles governing the concept of demonstrability, the paradoxes of demonstrability presented here tend to undermine the concept itself—or at least our understanding of it. As long as we cannot find a diagnosis and a cure for the paradoxes, it seems that the coherence of the concepts of demonstrability and demonstrable knowledge are put in question. There are of course ways of putting the paradoxes in quarantine, for example by imposing a hierarchy of languages a` la Tarski, or a ramified hierarchy of propositions and propositional functions a` la Russell. These measures, however, helpful as they may be in avoiding contradictions, do not seem to solve the underlying conceptual problems. Although structurally similar to the semantic paradoxes, the paradoxes discussed in this paper involve epistemic notions: “demonstrability”, “knowability”, “knowledge”... These notions are “factive” (e.g., if A is demonstrable, then A is true), but similar paradoxes arise in connection with “nonfactive” notions like “believes”, “says”, “asserts”.3 There is no consensus in the literature concerning the analysis of the notions involved—often referred to as “propositional attitudes”—or concerning the treatment of the paradoxes they give rise to. (shrink)

Factive mental states, such as knowing or being aware, can only link an agent to the truth; by contrast, nonfactive states, such as believing or thinking, can link an agent to either truths or falsehoods. Researchers of mental state attribution often draw a sharp line between the capacity to attribute accurate states of mind and the capacity to attribute inaccurate or “reality-incongruent” states of mind, such as false belief. This article argues that the contrast that really matters for mental (...) state attribution does not divide accurate from inaccurate states, but factive from nonfactive ones. (shrink)

Frege begins his discussion of factives in ‘On Sense and Reference’ with an example of a purported contrafactive, that is, a verb that entails, or presupposes, the falsity of the complement sentence. But the verb he cites, ‘wähnen’, is now obsolete, and native speakers are sceptical about whether it really was a contrafactive. Despite the profusion of factive verbs, there are no clear examples of contrafactive propositional attitude verbs in English, French or German. This paper attempts to give an (...) explanation of this, and to use this to shed light on the behaviour of factives more generally. The suggestion is that factive propositional attitude verbs take facts, not propositions, as the referents of their complement sentences; and that as there are no contra-facts, there can be no contra-factives. This claim is also used to help explain Timothy Williamson's observation that there is no stative propositional attitude factive that requires only belief. Various conclusions are drawn within a broadly ‘knowledge first’ approach. (shrink)

In “The Myth of Factive Verbs” (Hazlett 2010), I had four closely related goals. The first (pp. 497-99, p. 522) was to criticize appeals to ordinary language in epistemology. The second (p. 499) was to criticize the argument that truth is a necessary condition on knowledge because “knows” is factive. The third (pp. 507-19) – which was the intended means of achieving the first two – was to defend a semantics for “knows” on which <S knows p> can (...) be true even if p isn’t true. The fourth (Ibid.) – which seemed necessary for the success of the third – was to defend a pragmatic account of the fact that utterances of <S knows p> typically imply p, on which the implication in those cases is down to conversational implicature. In this paper I’ll go after these goals again, with an emphasis on the second. Our topic will be whether the factivity of “knows” (whatever this amounts to) supports the truth condition on knowledge. A new goal will be to defend my argument against some criticisms from John Turri (2011) and Savas Tsohatzidis (forthcoming). We’ll first look at the truth condition (§1) and factive presupposition (§§2 – 3), before turning to replies to Turri and Tsohatzidis (§§4 – 7). (shrink)

We present a formal semantics for epistemic logic, capturing the notion of knowability relative to information (KRI). Like Dretske, we move from the platitude that what an agent can know depends on her (empirical) information. We treat operators of the form K_AB (‘B is knowable on the basis of information A’) as variably strict quantifiers over worlds with a topic- or aboutness- preservation constraint. Variable strictness models the non-monotonicity of knowledge acquisition while allowing knowledge to be intrinsically stable. Aboutness-preservation (...) models the topic-sensitivity of information, allowing us to invalidate controversial forms of epistemic closure while validating less controversial ones. Thus, unlike the standard modal framework for epistemic logic, KRI accommodates plausible approaches to the Kripke-Harman dogmatism paradox, which bear on non-monotonicity, or on topic-sensitivity. KRI also strikes a better balance between agent idealization and a non-trivial logic of knowledge ascriptions. (shrink)

In epistemology and philosophy of science, there has been substantial debate about truth’s relation to understanding. “Non-factivists” hold that radical departures from the truth are not always barriers to understanding; “quasi-factivists” demur. The most discussed example concerns scientists’ use of idealizations in certain derivations of the ideal gas law from statistical mechanics. Yet, these discussions have suffered from confusions about the relevant science, as well as conceptual confusions. Addressing this example, we shall argue that the ideal gas law is best (...) interpreted as favoring non-factivism about understanding, but only after delving a bit deeper into the statistical mechanics that has informed these arguments and stating more precisely what non-factivism entails. Along the way, we indicate where earlier discussions have gone astray, and highlight how a naturalistic approach furnishes more nuanced normative theses about the interaction of rationality, understanding, and epistemic value. (shrink)

This is a comment on Moti Mizrahi's paper ' You Can't Handle the Truth: Knowledge = Epistemic Certainty'. Mizrahi claims that the factivity of knowledge entails that knowledge requires epistemic certainty. But the argument that Mizrahi presents does not proceed from factivity to certainty. Instead, it proceeds from a premise about the relationship between grounds and knowledge to the conclusion about certainty.

This is a reply to Howard Sankey’s comment (“Factivity or Grounds? Comment on Mizrahi”) on my paper, “You Can’t Handle the Truth: Knowledge = Epistemic Certainty,” in which I present an argument from the factivity of knowledge for the conclusion that knowledge is epistemic certainty. While Sankey is right that factivity does not entail epistemic certainty, the factivity of knowledge does entail that knowledge is epistemic certainty.

This paper draws out and connects two neglected issues in Kant’s conception of a priori knowledge. Both concern topics that have been important to contemporary epistemology and to formal epistemology in particular: knowability and luminosity. Does Kant commit to some form of knowability principle according to which certain necessary truths are in principle knowable to beings like us? Does Kant commit to some form of luminosity principle according to which, if a subject knows a priori, then they can (...) know that they know a priori? I defend affirmative answers to both of these questions, and by considering the special kind of modality involved in Kant’s conceptions of possible experience and the essential completability of metaphysics, I argue that his combination of knowability and luminosity principles leads Kant into difficulty. (shrink)

How radical is the idea that reasons are factive? Some philosophers consider it a dramatic departure from orthodoxy, with surprising implications about the bearing of the external world on what credences it’s reasonable to have, what beliefs are epistemically appropriate, and what actions are rational. I deny these implications. In the cases where external matters imply differences in factive states, there will inevitably be important weaker factive states in common. For example, someone who knows it is raining (...) has many factive states in common with someone who has a Gettiered belief that it is raining, or one who falsely but justifiably believes that it is raining. The factive reasons denied to subjects in Gettier cases or skeptical scenarios are in an important sense redundant; appropriate belief or action supervenes on internal states, even if reasons must be factive (and even if appropriate belief and action supervenes on reasons). The degree to which the strategy is applicable depends substantively on epistemic assumptions about basic or foundational knowledge. I argue that even given a significantly externalist approach to the latter internalist intuitions about rational credence, belief, and action can be vindicated. (shrink)

In the recent literature, several authors have argued that the capacity to track factive mental states plays a central role in explaining our ability to understand and predict people’s behavior (Nagel 2013; Nagel 2017; Phillips & Norby 2019; Phillips et al. 2020; Westra & Nagel 2021). The topic of this chapter is whether this capacity also enters into an explanation of our ability to track skilled and intentional actions.

Fitch's knowability paradox shows that for each unknown truth there is also an unknowable truth, a result which has been thought both odd in itself and at odds with views which impose epistemic constraints on truth and/or meaningfulness. Here a solution is considered which has received little attention in the debate but which carries prima facie plausibility. The decidability solution is to accept that Fitch sentences are unknowably true but deny the significance of this on the grounds that Fitch (...) sentences are nevertheless decidable. The decidability solution is particularly attractive for those whose primary concern is an epistemic constraint on meaningfulness (‘verificationists’). For those whose main concern is truth (‘anti-realists’), the situation is more complex: Melia takes the solution to exonerate anti-realism completely; Williamson sees it as completely irrelevant. The truth lies between these two extremes: there is one broad anti-realist commitment to which the solution does not apply, but there is also one, the “fundamental tenet” of anti-realism according to Dummett, to which it does. (shrink)

Suppose that A explains B. Do A and B need to be true? Provided that we have metaphysical explanation in mind, orthodoxy answers “yes:” metaphysical explanation is factive. This article introduces and defends a non-factive notion of metaphysical explanation. I argue that we need a non-factive notion of explanation in order to make sense of explanationist arguments where we motivate a view by claiming that it offers better explanations than its competitors. After presenting and rejecting some initially (...) plausible rivals, I account for non-factive metaphysical explanation by drawing on existing applications of structural equation models to metaphysical grounding. (shrink)

Anti-realism is plagued by Fitch’s paradox: the remarkable result that if one accepts that all truths are knowable, minimal assumptions about the nature of knowledge entail that every truth is known. Dorothy Edgington suggests to address this problem by understanding p is knowable to be a counterfactual claim, but her proposal must contend with a forceful objection by Timothy Williamson. I revisit Edgington’s basic idea and find that Williamson’s objection is obviated by a refined understanding of counterfactual knowability that (...) is grounded in possible courses of inquiry. I arrive at a precise definition of knowability that is not just a technical avoidance of paradox, but is metaphysically sound and does justice to the anti-realist idea. (shrink)

It’s a cornerstone of epistemology that knowledge requires truth – that is, that knowledge is factive. Allan Hazlett boldly challenges orthodoxy by arguing thatthe ordinary concept of knowledge is not factive. On this basis Hazlett further argues that epistemologists shouldn’t concern themselves with the ordinary concept of knowledge, or knowledge ascriptions and related linguistic phenomena. I argue that either Hazlett is wrong about the ordinary concept of knowledge, or he’s right in a way that leaves epistemologists to carry (...) on exactly as they have, paying attention to much the same things they always did. (shrink)

According to factive accounts of the norm of belief and decision-making, you should not believe or base decisions on a falsehood. Even when the evidence misleadingly suggests that a false proposition is true, you should not believe it or base decisions on it. Critics claim that factive accounts are counterintuitive and badly mischaracterize our ordinary practice of evaluating beliefs and decisions. This paper reports four experiments that rigorously test the critic’s accusations and the viability of factive accounts. (...) The results undermine the accusations and provide the best evidence yet of factive norms of belief and decision-making. The results also help discriminate between two leading candidates for a factive norm: truth and knowledge. Knowledge is the superior candidate. (shrink)

kk states that knowing entails knowing that one knows, and K¬K states that not knowing entails knowing that one does not know. In light of the arguments against kk and K¬K⁠, one might consider modally qualified variants of those principles. According to weak kk, knowing entails the possibility of knowing that one knows. And according to weakK¬K⁠, not knowing entails the possibility of knowing that one does not know. This paper shows that weak kk and weakK¬K are much stronger than (...) they initially appear. Jointly, they entail kk and K¬K⁠. And they are susceptible to variants of the standard arguments against kk and K¬K⁠. This has interesting implications for the debate on positive introspection and for deeper issues concerning the structure and limits of knowability. (shrink)

Perceptions guide our actions and provide us with evidence of the world around us. Illusions and hallucinations can mislead us: they may prompt as to act in ways that do not mesh with the world around us and they may lead us to form false beliefs about that world. The capacity view provides an account of evidence that does justice to these two facts. It shows in virtue of what illusions and hallucinations mislead us and prompt us to act. Moreover, (...) it shows in virtue of what we are in a better epistemic position when we perceive than when we hallucination. In this paper, I develop the capacity view, that is, the view that perceptual experience has epistemic force in virtue of the epistemic and metaphysical primacy of the perceptual capacities employed in perception. By grounding the epistemic force of experience in facts about the metaphysical structure of experience, the capacity view is not only an externalist view, but moreover a naturalistic view of the epistemology of perceptual experience. So it is an externalist and naturalistic alternative to reliabilism. I discuss the repercussions of this view for the justification of beliefs and the epistemic transparency of mental states, as well as, familiar problem cases. (shrink)

A novel solution to the knowability paradox is proposed based on Kant’s transcendental epistemology. The ‘paradox’ refers to a simple argument from the moderate claim that all truths are knowable to the extreme claim that all truths are known. It is significant because anti-realists have wanted to maintain knowability but reject omniscience. The core of the proposed solution is to concede realism about epistemic statements while maintaining anti-realism about non-epistemic statements. Transcendental epistemology supports such a view by providing (...) for a sharp distinction between how we come to understand and apply epistemic versus non-epistemic concepts, the former through our capacity for a special kind of reflective self-knowledge Kant calls ‘transcendental apperception’. The proposal is a version of restriction strategy: it solves the paradox by restricting the anti-realist’s knowability principle. Restriction strategies have been a common response to the paradox but previous versions face serious difficulties: either they result in a knowability principle too weak to do the work anti-realists want it to, or they succumb to modified forms of the paradox, or they are ad hoc. It is argued that restricting knowability to non-epistemic statements by conceding realism about epistemic statements avoids all versions of the paradox, leaves enough for the anti-realist attack on classical logic, and, with the help of transcendental epistemology, is principled in a way that remains compatible with a thoroughly anti-realist outlook. (shrink)

The thesis that knowledge is a factive mental state plays a central role in knowledge-first epistemology, but accepting this thesis requires also accepting an unusually severe version of externalism about the mind. On this strong attitude externalism, whether S is in the mental state of knowledge can and often will rapidly change in virtue of changes in external states of reality with which S has no causal contact. It is commonly thought that this externalism requirement originates in the factivity (...) of knowledge. However, despite a number of recent defenses of non-factive accounts of knowledge, epistemology has yet to consider whether a non-factive approach might produce a version of the mental state thesis that can avoid strong externalism. Here I do just that, exploring how three different proposals for weakening factivity might be adapted to theories of knowledge as a non-factive mental state. Contrary to what we might expect, however, none of these proposals are compatible with anything close to attitude internalism about knowledge—or even a substantially weaker externalism. All told, the widespread view that wraps up the severe externalism required for knowledge to be a mental state in factivity is mistaken. Knowledge’s external-world connection runs far deeper than the factivity constraint. (shrink)

The main question addressed in this paper is whether some false sentences can constitute evidence for the truth of other propositions. In this paper it is argued that there are good reasons to suspect that at least some false propositions can constitute evidence for the truth of certain other contingent propositions. The paper also introduces a novel condition concerning propositions that constitute evidence that explains a ubiquitous evidential practice and it contains a defense of a particular condition concerning the possession (...) of evidence. The core position adopted here then is that false propositions that are approximately true reports of measurements can constitute evidence for the truth of other propositions. So, it will be argued that evidence is only quasi-factive in this very specific sense. (shrink)

In this paper we argue that standard, indexical contextualism about "knows" is unable to account for the factivity of this epistemic expression.

This paper defends and develops the capacity view against insightful critiques from Matt McGrath, Adam Pautz, and Ram Neta. In response to Matt McGrath, I show why capacities are essential and cannot simply be replaced with representational content. I argue moreover, that the asymmetry between the employment of perceptual capacities in the good and the bad case is sufficient to account for the epistemic force of perceptual states yielded by the employment of such capacities. In response to Adam Pautz, I (...) show why a perceiver’s belief is better justified than the belief of someone who suffers a subjectively indistinguishable hallucination. I show, moreover, why the capacity view is compatible with standard Bayesian principles and how it accounts for degrees of justification. In response to Ram Neta, I discuss the relationship between evidence and rational confidence, as well as the notion of evidence in light of an externalism about perceptual content. (shrink)

Fitch's Paradox and the Paradox of the Knower both make use of the Factivity Principle. The latter also makes use of a second principle, namely the Knowledge-of-Factivity Principle. Both the principle of factivity and the knowledge thereof have been the subject of various discussions, often in conjunction with a third principle known as Closure. In this paper, we examine the well-known Surprise Examination paradox considering both the principles on which this paradox rests and some formal characterisations of the surprise notion, (...) crucial in this paradox. Standard formalizations of the Surprise Examination paradox in modal logic do not seem, at first glance, to depend on either factivity or knowledge-of-factivity, but we will argue that both factivity and knowledge-of-factivity play a key implicit role in the paradox. Namely, they are implicitly, perhaps unintentionally, used in order to simplify the definition of surprise. We analyze modal logical formalizations of three versions of the paradox concluding that the Surprise Examination paradox is the result of two flaws: the assumption of knowledge-of-factivity, and the over-simplification of the definition of "surprise" accordingly. By fixing these two flaws, the Surprise Examination paradox vanishes. (shrink)

It is often claimed that anti-realism is a form of transcendental idealism or that Kant is an anti-realist. It is also often claimed that anti-realists are committed to some form of knowability principle and that such principles have problematic consequences. It is therefore natural to ask whether Kant is so committed, and if he is, whether this leads him into difficulties. I argue that a standard reading of Kant does indeed have him committed to the claim that all empirical (...) truths are knowable and that this claim entails that there is no empirical truth that is never known. I extend the result to a priori truths and draw some general philosophical lessons from this extension. However, I then propose a re-examination of Kant’s notion of experience according to which he carefully eschews any commitment to empirical knowability. Finally I respond to a remaining problem that stems from a weaker, justified believability principle. (shrink)

In recent discussions in this journal, Moti Mizrahi defends the claim that knowledge equals epistemic certainty. Howard Sankey finds Mizrahi’s argument to be problematic, since, as he reads it, this would entail that justification must guarantee truth. In this article, I suggest that an account of the normativity of justification is able to bridge the gap between Mizrahi’s proposal and Sankey’s objections.

The concept of knowledge can be modelled in epistemic modal logic and, if modelled by using a standard modal operator, it is subject to the problem of logical omniscience. The classical solution to this problem is to distinguish between implicit and explicit knowledge and to construe the knowledge operator as capturing the concept of implicit knowledge. In addition, since a proposition is said to be implicitly known just in case it is derivable from the set of propositions that are explicitly (...) known by using a certain set of logical rules, the concept of implicit knowledge is definable on the basis of the concept of explicit knowledge. In any case, both implicit and explicit knowledge are typically characterized as factive, i.e. such that it is always the case that what is known is also true. The aim of the present paper is twofold: first, we will develop a dynamic system of explicit intersubjective knowledge that allows us to introduce the operator of implicit knowledge by definition; secondly, we will show that it is not possible to hold together the following two theses: (1) the concept of implicit knowledge is definable along the lines indicated above and (2) the concept of implicit knowledge is factive. (shrink)

Why should we avoid incoherence? An influential view tells us that incoherent combinations of attitudes are such that it is impossible for all of those attitudes to be simultaneously vindicated by the evidence. But it is not clear whether this view successfully explains what is wrong with certain akratic doxastic states. In this paper I flesh out an alternative response to that question, one according to which the problem with incoherent combinations of attitudes is that it is impossible for all (...) of those attitudes to be simultaneously knowledgeable. This alternative response explains what is wrong with akratic combinations of attitudes using commonly accepted epistemological theses. The paper still shows how this proposal is able to explain the badness of incoherent combinations involving the absence of attitudes, suspended judgment and credence. These explanations deploy the notions of knowledge and being in a position to know, instead of the notion of responding properly to the evidence. Finally, I suggest that this picture can be generalized to the realm of practical rationality as well. (shrink)

I evaluate non-factive or truth-insensitive accounts of the ordinary concepts used to evaluate beliefs, evidence, assertions, and decisions. Recent findings show that these accounts are mistaken. I propose three hypotheses regarding how philosophers defending these accounts got things so wrong. I also consider one potential consequence for the discipline.

This paper is a response to Baumann's comments on "Can Knowledge Really be Non-fative?" In this paper Baumann's suggestions for how those who deny the factivty of knowledge might deal with the argument from inconsistency and explosion are addressed.

This paper contains a critical examination of the prospects for analyses of knowledge that weaken the factivity condition such that knowledge implies approximate truth.

It is widely thought that knowledge is factive – only truths can be known. However, this view has been recently challenged. One challenge appeals to approximate truths. Wesley Buckwalter and John Turri argue that false-but-approximately-true propositions can be known. They provide experimental findings to show that their view enjoys intuitive support. In addition, they argue that we should reject the factive account of knowledge to avoid widespread skepticism. A second challenge, advanced by Nenad Popovic, appeals to multidimensional geometry (...) to build a case where it seems intuitive that a person knows p even though p is false. In addition, Popovic argues that we should reject the factive account of knowledge because most of us would not become widespread skeptics if we discovered that ordinary objects in our world are actually four-dimensional. In this paper, we defend the factive account of knowledge against these arguments by challenging the intuitive appeal of the cases and arguing that there is no real threat of widespread skepticism for the factive account of knowledge. (shrink)

The topic of this article is the closure of a priori knowability under a priori knowable material implication: if a material conditional is a priori knowable and if the antecedent is a priori knowable, then the consequent is a priori knowable as well. This principle is arguably correct under certain conditions, but there is at least one counterexample when completely unrestricted. To deal with this, Anderson proposes to restrict the closure principle to necessary truths and Horsten suggests to restrict (...) it to formulas that belong to less expressive languages. In this article it is argued that Horsten’s restriction strategy fails, because one can deduce that knowable ignorance entails necessary ignorance from the closure principle and some modest background assumptions, even if the expressive resources do not go beyond those needed to formulate the closure principle itself. It is also argued that it is hard to find a justification for Anderson’s restricted closure principle, because one cannot deduce it even if one assumes very strong modal and epistemic background principles. In addition, there is an independently plausible alternative closure principle that avoids all the problems without the need for restriction. (shrink)

In this paper I give a novel argument for the view that epistemic normative reasons (or evidence) need not be facts. I first argue that the nature of normative reasons is uniform, such that our positions about the factivity of reasons should agree across normative realms –– whether epistemic, moral, practical, or otherwise. With that in mind, I proceed in a somewhat indirect way. I argue that if practical motivating reasons are not factive, then practical normative reasons are not (...) factive. If it is possible to act rationally in the light of a falsehood, as I will say, then some good reasons must be falsehoods. The implication of this argument is perhaps surprising: for one to firmly establish the view that epistemic normative reasons are factive, one must discredit the view that practical motivating reasons are not factive. (shrink)

History and Philosophy of Logic, Volume 33, Issue 1, Page 101-104, February 2012.

A dynamic epistemic logic is presented in which the single agent can reason about his knowledge stages before and after announcements. The logic is generated by reinterpreting multi agent private announcements in a single agent environment. It is shown that a knowability principle is valid for such logic: any initially true ϕ can be known after a certain number of announcements.

There are three main accounts of scientific progress: 1) the epistemic account, according to which an episode in science constitutes progress when there is an increase in knowledge; 2) the semantic account, according to which progress is made when the number of truths increases; 3) the problem-solving account, according to which progress is made when the number of problems that we are able to solve increases. Each of these accounts has received several criticisms in the last decades. Nevertheless, some authors (...) think that the epistemic account is to be preferred if one takes a realist stance. Recently, Dellsén proposed the noetic account, according to which an episode in science constitutes progress when scientists achieve increased understanding of a phenomenon. Dellsén claims that the noetic account is a more adequate realist account of scientific progress than the epistemic account. This paper aims precisely at assessing whether the noetic account is a more adequate realist account of progress than the epistemic account. (shrink)

Widespread amongst scholars is the legend according to which Locke shows a strong aversion to abstract ideas, similar to that of Berkley in the Treatise. This legend is endorsed by influential commentators on Locke. He does not even propose the reduction of ideas to mental pictures (a reduction which in Berkeley and Hume will form the base of the negation of the existence of abstract ideas in the mind). Locke is not in the least afraid of abstract ideas; his constant (...) concern, which is evident in his treatment of the complex question of the relation between real and nominal essence, is to refute the position of the Scholastics, according to which a universal concept in the mind (post rem) reflects the universal present in all things as substantial form (the universal in re), without assuming positions which are purely conventionalist and nominalist with regard to knowledge, such as those of Mersenne, Gassendi, Hobbes and sceptical and anti-Cartesian free-thinkers. To show this, I offer an analysis of the relation Locke makes between real and nominal essence, with regard to the relations which link term to idea and idea to things. The nature of the relation between signifier and signified is variable, though, in the relation between ideas and things with respect to the various kinds of complex ideas which the human mind may frame. The greatest difference is to be found between complex ideas of mixed mode and complex ideas of substance. (shrink)

Philosophers are divided over moral internalism, the claim that moral judgement entails some motivation to comply with that judgement. Against moral internalism, externalists defend the conceptual coherence of scenarios in which an individual makes genuine moral judgements but is entirely unmoved by them. This is amoralist skepticism and these scenarios can be called amoralist scenarios. While the coherence of amoralist scenarios is disputed, philosophers seem to agree that the coherence of amoralist scenarios is not affected by whether the amoralist is (...) described as having moral knowledge or mere belief. But recent experimental research challenges this assumption. When evaluating amoralist scenarios, people’s intuitions lean towards externalism when the amoralist is described as knowing that X is morally wrong, whereas people’s intuitions lean towards internalism when the amoralist is described as believing that X is morally wrong. Call this the factivity effect. In this paper, I argue that the factivity effect is unlikely to be explained as an experimental artifact and that as a consequence, the traditional dispute over moral internalism and amoralist skepticism may need a major overhaul. The results of three studies testing the factivity effect provide support for this thesis. Implications of these results for the traditional debate over moral internalism are discussed. (shrink)