The paper argues against Timothy Williamson's anti-luminosity argument. It also offers an argument against luminosity from the possibility of defeat of introspective justification.

Tim defines a "luminous" condition as one that we are always in a position to know that we are in, whenever we are in it. To explain the idea of being in a position to know, Tim tells us that we are in a position to know a proposition when it states a fact that is open to our view, unhidden, and with no obstacle to our knowing it. He also tells us that if we are in a position to (...) know a proposition, and we do what we are in a position to do toward knowing whether or not it is true, then we know it to be true. So a luminous condition obtains only if it is all set to be known to obtain by the one in the condition. (shrink)

I know various contingent truths about my environment by perception. For example, by looking, I know that there is a computer before me; by hearing, I know that someone is talking in the corridor; by tasting, I know that the coffee has no sugar. I know these things because I have some built-in mechanisms specialized for detecting the state of my environment. One of these mechanisms, for instance, is presently transducing electromagnetic radiation (in a narrow band of wavelengths) coming from (...) the computer and the desk on which it sits. How that mechanism works is a complicated story—to put it mildly—and of course much remains unknown. But we can at least produce more-or- less plausible sketches of how the mechanism can start from retinal irradiation, and go on to deliver knowledge of my surroundings. Moreover, in the sort of world we inhabit, specialized detection mechanisms that are causally affected by the things they detect have no serious competition—seeing the computer by seeing an idea of the computer in the divine mind, for example, is not a feasible alternative. (shrink)

This essay is a long one. It is not meant to be read in a single sitting. Its structure is as follows. In section I, I explicate perceptual anti-individualism. Section II centers on the two aspects of the representational content of perceptual states. Sections III and IV concern the nature of the empirical psychology of vision, and its bearing on the individuation of perceptual states. Section V shows how what is known from empirical psychology undermines disjunctivism and hence certain further (...) views that entail it, including naive realism. In Section VI, I raise a further point against disjunctivism. Section VII indicates how general reflection on perceptual perspective and epistemic ability supports the constraints from empirical psychology. It also explains how reflection on veridicality conditions, psychological explanation, and cognitive ability conspire to force recognition of the two kinds of representation mentioned in the preceding paragraph. In the Appendix, I criticize attempts to support disjunctivism. (shrink)

By means of an example, shows the possibility of beliefs that are separately rational whilst together inconsistent.

The paper argues that, although a distinction between a priori and a posteriori knowledge (or justification) can be drawn, it is a superficial one, of little theoretical significance. The point is not that the distinction has borderline cases, for virtually all useful distinctions have such cases. Rather, it is argued by means of an example, the differences even between a clear case of a priori knowledge and a clear case of a posteriori knowledge may be superficial ones. In both cases, (...) experience plays a role that is more than purely enabling but less than strictly evidential. It is also argued that the cases at issue are not special, but typical of a wide range of others, including knowledge of axioms of set theory and of elementary logical truths. Attempts by Quine and others to make all knowledge a posteriori (‘empirical’) are repudiated. The paper ends with a call for a new framework to be developed for analysing the epistemology of cognitive uses of the imagination. (shrink)

After introducing semantic anti-realism and the paradox of knowability, the paper offers a reconstruction of the anti-realist argument from understanding. The proposed reconstruction validates an unrestricted principle to the effect that truth requires the existence of a certain kind of “demonstration”. The paper shows that that principle fails to imply the problematic instances of the original unrestricted feasible-knowability principle but that the overall view underlying the new principle still has unrestricted epistemic consequences. Appealing precisely to the paradox of knowability, the (...) paper also argues, against the BHK semantics, for the non- constructive character of the demonstrations envisaged by semantic anti-realism, and contends that, in such setting, one of the most natural arguments for a broadly intuitionist revision of classical logic loses all its force.Tras presentar el anti-realismo semántico y la paradoja de la cognoscibilidad, el artículo ofrece una reconstrucción del argumento anti-realista basado en la comprensión. La reconstrucción que se propone valida un principio irrestricto, del que se sigue que la verdad requiere la existencia de un determinado tipo de “demostración”. El artículo muestra que este principio no implica las instancias problemáticas del original principio irrestricto de la cognoscibilidad realizable, y que la concepción general que subyace al nuevo principio todavía tiene consecuencias epistémicas irrestrictas. Apelando precisamente a la paradoja de la cognoscibilidad, el artículo argumenta además, en contra de la semántica BHK, a favor del carácter no constructivo de las demostraciones que contempla el anti-realismo semántico, y defiende que, en ese marco, uno de los argumentos más naturales a favor de una revisión a grandes rasgos intuicionista de la lógica clásica pierde toda su fuerza. (shrink)

After introducing semantic anti-realism and the paradox of knowability, the paper offers a reconstruction of the anti-realist argument from the theory of understanding. The proposed reconstruction validates an unrestricted principle to the effect that truth requires the existence of a certain kind of “demonstration”. The paper shows that the principle fails to imply the problematic instances of the original unrestricted knowability principle but that the overall view still has unrestricted epistemic consequences. Appealing precisely to the paradox of knowability, the paper (...) also argues, against BHK semantics, for the non-constructive character of the demonstrations envisaged by anti-realists, and contends that, in such a setting, one of the most natural arguments in favour of a revision of classical logic loses all its force. (shrink)

Intellectualism is the doctrine that knowing how to do something consists in knowing that something is the case. Drawing on contemporary linguistic theories of indirect questions, Jason Stanley and Timothy Williamson have recently revived intellectualism, proposing to interpret a sentence of the form ‘s knows how to F’ as ascribing to s knowledge of a certain way w of Fing that she can F in w. In order to preserve knowledgehow’s connection to action and thus avoid an overgeneration problem, they (...) add that this knowledge must be had under a “practical” mode of presentation of w. I argue that (i) there can be non-knowledgeable true beliefs under a practical mode of presentation and that (ii) some such beliefs would nevertheless be sufficient to establish knowledge-how’s characteristic connection to action, and thus count as knowledge-how. If so, Stanley & Williamson’s account is faced with a serious undergeneration problem. Moreover, the structural features on which the argument relies make it likely to present a quite general challenge for intellectualist strategies. (shrink)

The paper discusses some ways in which the phenomenon of borderline cases may be thought to bear on the traditional philosophical idea that certain domains of facts are fully open to our view. The discussion focusses on a very influential argument (due to Tim Williamson) to the effect that, roughly, no such domains of luminous facts exist. Many commentators have felt that the vagueness unavoidably inherent in the description of the facts that are best candidates for being luminous plays an (...) illicit role in the argument. The paper investigates this issue by centring around the idea that vagueness brings with itself borderline cases, and that these in turn generate absence of a fact of the matter and hence epistemically benign lack of knowledge. It is argued that, given the possibility of absence of a fact of the matter, the idea of luminosity should be reformulated using the notion of determinacy, and that the resulting reformulation is not immediately subject to the original anti-luminosity argument. However, it is shown that the specific understanding of determinacy required by this strategy validates a new argument against the reformulated version of luminosity. Moreover, reflection on the connection between mistake and absence of a fact of the matter offers another argument against such version, with the surprising upshot that, granting the soundness of the original anti-luminosity argument, not even the determinacy of a certain fact would guarantee its knowability. (shrink)

The paper discusses some ways in which vagueness and its phenomena may be thought to impose certain limits on our knowledge and, more specifically, may be thought to bear on the traditional philosophical idea that certain domains of facts are luminous, i.e., roughly, fully open to our view. The discussion focuses on a very influential argument to the effect that almost no such interesting domains exist. Many commentators have felt that the vagueness unavoidably inherent in the description of the facts (...) that are best candidates for being luminous plays an illicit role in such argument. The paper centres around the idea that vagueness brings with itself the prima facie plausibility of soritical principles. Using the diagnostics of sharpenings, it is first pointed out that, despite certain considerations to the contrary, the margin‐for‐error principle required by the anti‐luminosity argument may well derive all of its plausibility from an underlying soritical principle. The notion of confidence that is relevant to the argument is then isolated and sharply distinguished from the notion of subjective probability. Against this background, it is argued that the reasoning about confidence involved in the argument in favour of the problematic margin‐for‐error principle is fallacious in the same way in which sorites reasoning is. This reveals the possibility of having reliable knowledge even at the penumbral limit with falsity, a possibility for which a concrete formal model is constructed. The model in turn permits a deeper appreciation of the role played in the dialectic by the distinction between confidence and subjective probability as well as by confidence requirements on knowledge. It is concluded that careful heeding of vagueness and its phenomena, far from forcing new and surprising limits on our knowledge, actually removes one of the main barriers – unreliability – often thought to stand in its way. (shrink)

The paper critically discusses two prominent arguments against closure principles for knowledge. The first one is the “argument from aggregation”, claiming that closure under conjunction has the consequence that, if one individually knows i premises, one also knows their i-fold conjunction—yet, every one of the premises might exhibit interesting positive epistemic properties while the i-fold conjunction might fail to do so. The second one is the “argument from concatenation”, claiming that closure under entailment has the consequence that, if one knows (...) a premise, one also knows each of its remote consequences one arrives at—yet, again, the premise might exhibit interesting positive epistemic properties while some of its remote consequences might fail to do so. The paper firstly observes that the ways in which these two arguments try to establish that the relevant closure principle has the relevant problematic consequence are strikingly similar. They both crucially involve showing that, given the features of the case, the relevant closure principle acts in effect as a soritical principle, which is in turn assumed to lead validly to the relevant problematic consequence. There are however nontransitive logics of vagueness where soritical principles do not have any problematic consequence. Assuming that one of these logics is the correct logic of vagueness, the paper secondly observes that both arguments describe situations where knowledge is arguably vague in the relevant respects, so that a tolerant logic should be used in reasoning about it, with the effect that the relevant soritical principle no longer validly leads to the relevant problematic consequence. This shows an interesting respect in which the gap between validity and good inference that arguably arises in a transitive framework can be bridged in a tolerant one, thereby approximating better certain features of our epistemic lives as finite subjects. Moreover, even for those who do not subscribe to tolerant logics, the paper’s two observations jointly indicate that, for all the arguments from aggregation and concatenation show, the status of the relevant closure principles should be no worse than that assigned by one’s favoured theory of vagueness to soritical principles, which only rarely is plain falsity and can indeed get arbitrarily close to full truth. (shrink)

Most of our knowledge is inexact, and known by us to be so. An example of such known inexactness will be described in some detail. The description seems to entail a contradiction. However, the paradoxical reasoning rests on an assumption. It will be suggested that the description is correct and this assumption false. Its failure will be explained by means of a picture of inexact knowledge in which the notion of a margin for error is central. This picture suggests diagnoses (...) of other paradoxical arguments: Surprise Examinations, backwards inductions about Iterated Prisoner's Dilemma, and the Heap. (shrink)

Since its appearance over a decade ago, Timothy Williamson's anti-luminosity argument has come under sustained attack. Defenders of the luminous overwhelmingly object to the argument's use of a certain margin-for-error premise. Williamson himself claims that the premise follows easily from a safety condition on knowledge together with his description of the thought experiment. But luminists argue that this is not so: the margin-for-error premise either requires an implausible interpretation of the safety requirement on knowledge, or it requires other equally implausible (...) assumptions. In this paper I bolster the margin-for-error premise against these attacks by recasting Williamson's own two-part defence, the first part intended to work on the assumption that there is no constitutive connection between the phenomenal and the doxastic, and the second intended to work without this assumption. Pace various luminists, I argue that the appeals to safety needed for Williamson's two-part defence are plausible. I also argue that all that is needed to generate the margin-for-error premise from these safety conditions is an empirical assumption about the kinds of creatures we are: that is, creatures whose beliefs are structured by certain dispositions. By recasting the anti-luminosity argument in this way, we can understand what is really at stake in the debate about luminosity: that is, whether we are luminous. (shrink)

In this paper, we present a number of problems for intellectualism about knowledge-how, and in particular for the version of the view developed by Stanley & Williamson 2001. Their argument draws on the alleged uniformity of 'know how'-and 'know wh'-ascriptions. We offer a series of considerations to the effect that this assimilation is problematic. Firstly, in contrast to 'know wh'-ascriptions, 'know how'-ascriptions with known negative answers are false. Secondly, knowledge-how obeys closure principles whose counterparts fail for knowledge-wh and knowledge-that. Thirdly, (...) as opposed to knowledge-wh and knowledge-that, knowledge-how is inferentially isolated from further knowledge-that. We close by providing some evidence against the further reduction of knowledge-wh to knowledge-that, which is presupposed by the intellectualist theory under discussion. (shrink)

En Knowledge and its Limits, Timothy Williamson argumenta a favor de la tesis fuerte de que el conocimiento es un estado mental, ofreciendo una caracterización del conocimiento según la cual es "la actitud factiva estativa más general". Dicha caracterización es central una vez que se considera que los estados perceptivos son también actitudes factivas estativas. Esta propuesta ha sido discutida ampliamente en la literatura. En este trabajo argumento en contra de a partir de una crítica novedosa que parte de las (...) herramientas mismas que Williamson usa a su favor. Para ello argumentaré, en distintas etapas, que los estados perceptivos no son actitudes factivas estativas. La crítica en cuestión no se limita a mostrar la falsedad de la caracterización del conocimiento en términos de actitudes factivas estativas, sino que también muestra la implausibilidad de. (shrink)

(NEG) is widely accepted both by internalist and by externalists. In fact, there have been very few opponents of (NEG). Timothy Williamson (e.g., 2000) rejects (NEG), for reasons that have by now received a great deal of scrutiny.2 John McDowell also rejects (NEG), but his reasons have not received the scrutiny they deserve. This is in large part because those reasons have not been well understood. We believe that McDowell’s challenge to (NEG) is important, worthy of fair assessment, and maybe (...) even correct. In this paper, we explain McDowell’s challenge to (NEG), and also explain how McDowell can address a seemingly fatal objection to his view. (shrink)

We often talk about knowledge being transmitted via testimony. This suggests a picture of testimony with striking similarities to memory. For instance, it is often assumed that neither is a generative source of knowledge: while the former transmits knowledge from one speaker to another, the latter preserves beliefs from one time to another. These considerations give rise to a stronger and a weaker thesis regarding the transmission of testimonial knowledge. The stronger thesis is that each speaker in a chain of (...) testimonial transmission must know that p in order to pass this knowledge to a hearer. The weaker thesis is that at least the first speaker must know that p in order for any hearer in the chain to come to know that p via testimony. I argue that both theses are false, and hence testimony, unlike memory, can be a generative source of knowledge. (shrink)

We often talk about knowledge being transmitted via testimony. This suggests a picture of testimony with striking similarities to memory. For instance, it is often assumed that neither is a generative source of knowledge: while the former transmits knowledge from one speaker to another, the latter preserves beliefs from one time to another. These considerations give rise to a stronger and a weaker thesis regarding the transmission of testimonial knowledge. The stronger thesis is that each speaker in a chain of (...) testimonial transmission must know that p in order to pass this knowledge to a hearer. The weaker thesis is that at least the first speaker must know that p in order for any hearer in the chain to come to know that p via testimony. I argue that both theses are false, and hence testimony, unlike memory, can be a generative source of knowledge. (shrink)

überall einen richtigen Gebrauch der reinen Vernunft giebt, in welchem Fall es auch einen Canon derselben geben muß, so wird dieser nicht den speculativen, sondernden pr.ntischen Vernunftgebrauch betreffen, den wir also iezt ...

Many philosophers believe that there is a fundamental distinction between knowing that something is the case and knowing how to do something. According to Gilbert Ryle, to whom the insight is credited, knowledge-how is an ability, which is in turn a complex of dispositions. Knowledge-that, on the other hand, is not an ability, or anything similar. Rather, knowledge-that is a relation between a thinker and a true proposition.

There is a constant temptation in philosophy to postulate a realm of phenomena in which nothing is hidden from us. Rene Descartes thought that one's own mind is such a realm. Ludwig Wittgenstein' enlarged the realm to everything that is of interest to philosophy. That they explained this special feature in very different ways hardly needs to be said; what is remarkable is their agreement on our possession of a cognitive home in which everything lies open to our view. Much (...) of our thinking – for example, in the physical sciences – must operate outside this home, in alien circumstances. The claim is that not all our thinking could be like that. (shrink)

This paper distinguishes and interrelates a number of respects in which persons have been thought to be in a specially favorable epistemic position vis-A-Vis their own mental states. The most important distinction is a six-Fold one between infallibility, Omniscience, Indubitability, Incorrigibility, Truth-Sufficiency, And self-Warrant. Each of these varieties can then be sub-Divided as the kind of modality, If any, Involved. It is also argued that discussions of self-Knowledge have been hampered by a failure to recognize these distinctions.

N. B. Prof Williamson is now based at the Faculty of Philosophy, University of Oxford.