Defenders of the Knowledge Argument contend that physicalism is false because knowing all the physical truths is not sufficient to know all the truths about the world. In particular, proponents of the Knowledge Argument claim that physicalism is false because the truths about the character of conscious experience are not knowable from the complete set of physical truths. This dissertation is a defense of the Knowledge Argument. Chapter one characterizes what physicalism is and provides support for the claim that if knowing all the physical truths is not sufficient to know all the truths about the world, then physicalism is false. In chapter two, I defend the claim that knowing all the physical truths is not sufficient for knowing all the truths about the world. In addition to mounting a prima facie case for the knowledge intuition, I present and defend an epistemology grounded in direct acquaintance to provide a more substantive argument to accept it. Chapters three through five address the physicalist objections to the Knowledge Argument. The first set of objections advocates that knowing all the physical truths is, in fact, sufficient for knowing all the truths about the world. The next set of objections admits that there is some sense in which knowing all the physical truths is not sufficient for knowing all the truths about the world. However, these objections maintain that the kind of knowledge that is absent from the complete set of physical truths is know-how or knowledge by acquaintance, and not factual or propositional knowledge. The final set of objections maintain that the kind of propositional knowledge that is left out of the complete set of physical truths is compatible with physicalism. My response to these objections is part of advancing my prima facie case for the Knowledge Argument. The final chapter addresses a structural question that pertains to the Knowledge Argument. Some philosophers have maintained that the structure of the Knowledge Argument invites a kind of self-refutation of any systematic account of reality. The concern is that the Knowledge Argument proves too much, and that the dualist who uses the argument to refute physicalism risks the argument defeating his own position. I will argue that the Knowledge Argument does not refute dualism.

A number of recent objections to physicalism are based on the apparent gap between physical knowledge and phenomenal knowledge. In response, some physicalists accept the epistemic gap, but deny the inference from the epistemic gap to a metaphysical gap. One popular strategy is to argue that there is something unique about our phenomenal concepts, the concepts that we use to think about our phenomenal states in terms of their subjective character, that explains the apparent gap. I develop a version of this strategy.Specifically, I argue that phenomenal-physical identities are necessarily true. These identities only seem contingent due to peculiarities of our phenomenal concepts. Phenomenal concepts have a unique connection to their referents; they are "self-presenting" concepts, which include their referents as components of the concepts themselves. Regardless of how we conceptualize the world, a phenomenal concept will always refer to the phenomenal state. But this is not true of non-phenomenal concepts, even concepts like `H2O' that seem to get at the essence of their referents. There is always an element of contingency in the connection between a non-phenomenal concept and its referent.When we consider an identity between a phenomenal concept and a non-phenomenal concept, like `pain = the firing of p-neurons', the more intimate connection between the phenomenal concept and its referent generates the intuition that the two concepts could come apart. This is true in a sense. If we were to adopt conceptualize things differently, the physical concept might not refer to the same state. For example, if we were to adopt a different theory of neuroscience, we might not conceptualize the firing of p-neurons as `the firing of p-neurons'. Phenomenal concepts, on the other hand, will always pick out the same referents, regardless of how we represent the world. For this reason, the concepts `pain' and `the firing of p-neurons' do come apart, but not in a sense that makes trouble for physicalism. What is possible is not a world in which pain isn't identical to the firing of p-neurons, but only a world in which pain isn't conceptualized as the firing of p-neurons.

This paper explores and evaluates the famous Mary case put forward by Frank Jackson in support of what he calls the knowledge argument against physicalism. After laying out Jackson’s position, I set out to determine whether certain previous physicalist attempts at undermining it have been successful. Finding that they have not, I use their shortcomings to inform the construction of a new position, one which I argue renders the Mary case at odds with itself and frees physicalism from the knowledge argument’s grasp.

Frank Jackson’s knowledge argument is a very influential piece of reasoning that seeks to show that colour experiences constitute an insoluble problem for science. This argument is based on a thought experiment concerning Mary. She is a vision scientist who has complete scientific knowledge of colours and colour vision but has never had colour experiences. According to Jackson, upon seeing coloured objects, Mary acquires new knowledge that escapes her complete scientific knowledge. He concludes that there are facts concerning colour experiences that scientific knowledge can neither describe nor explain. Specifically, these facts involve the occurrence of certain non-physical properties of experiences that he calls qualia. The present research considers whether a plausible formulation of the hypothesis that science can accommodate colour experiences is threatened by a version of the knowledge argument. The specific formulation of this problem has two motivations. Firstly, before investigating whether the knowledge argument raises a problem for the claim that science can account for colour experiences, we need a plausible formulation of this claim. I argue that the idea that science can accommodate colour experiences can be formulated as the modest reductionism hypothesis. Roughly speaking, this is the hypothesis that a science that can be explanatory interfaced with current physics of ordinary matter can account for conscious experiences. Secondly, an unintelligible premise figures in Jackson’s version the knowledge argument. Namely, it is assumed that Mary possesses a complete (future or possible) scientific knowledge. Nevertheless, the type of strategy involved in Jackson’s argument can be used to target modest reductionism. By considering contemporary psychophysics and neuroscience, I characterise Mary’s scientific knowledge. First, this characterisation is intelligible. In fact, it is elaborated on the basis of descriptions and explanations of colour experiences involved in current physics and neuroscience. Second, a supporter of modest reductionism can assume that the scientific knowledge ascribed to Mary might account for colour experiences. The main conclusion of the present research is that our version of the knowledge argument fails to threaten the modest reductionism hypothesis. In fact, I endorse what can be called the “two ways of thinking” reply to the knowledge argument. According to this response, the knowledge argument shows that there are different ways of thinking about colour experiences. One way of thinking is provided by scientific knowledge. The other way of thinking is provided by our ordinary conception of colour experiences. However, the existence of these two ways of thinking does not imply the existence of facts and properties that escape scientific knowledge. It might be the case that the ordinary way of thinking about colour experience concerns facts and properties described and explained by science. The principal conclusion of the research results from two investigations. The first line of research aims to reveal and evaluate the implicit assumptions that figure in the knowledge argument. The main body of the research is dedicated to this task. The principal result of this investigation is that the knowledge argument must rely on an account of introspective knowledge of colour experiences. I argue that an inferential model of introspection provides such account. On this model, Mary’s capacity to hold beliefs about her colour experiences when she sees coloured objects requires her mastery of colour concepts. The second main investigation seeks to justify the two ways of thinking strategy. As many opponents and supporters have recently started to realise, this strategy might be charged with being ad hoc. I offer a distinctive justification of this reply to the knowledge argument. Assuming the account of introspection mentioned above, the existence of visual recognitional colour concepts might justify this strategy. A person possesses these concepts when she is able to determine the colours of objects simply by having visual experiences.

Réduit à sa plus simple expression, ce travail de recherche met face à face deux acteurs s’affrontant dans un duel philosophique : le physicalisme et l’argument de la connaissance de Franck Jackson. La question clé autour de laquelle s’agencera notre discussion ici est (1) Est-il vrai que « Tout est physique » ? Le coeur de la thèse que nous défendons peut être résumé ainsi : (T) Le clivage post-platonicien (tacite) entre les formes objectivées et les formes subjectivées de la pensée, provoque des fossés explicatifs (explicites), qui sont franchis (très souvent) via des sauts conceptuels (mystérieux), intercalés entre les étapes d’une argumentation. Il sera argumenté ici que la distribution actuelle des débats sur l’axe états physiques (objectifs) / états qualitatifs (subjectifs) subit une pression souterraine post-platonicienne. Conséquemment, une bonne partie de l’énergie des penseurs actuels est dépensée à la recherche du « bon saut » ou « crochet » conceptuel permettant d’attacher les rives du mental à celui du physique. Nous soutiendrons que le coeur du problème ne consiste pas à résoudre le différend entre les physicalistes et les avocats des qualia, mais plutôt à trouver la réponse à la question : pourquoi en sommes-nous arrivés là, i.e., à ce clivage sur l’axe phénoménal/physique ? / “Everything is physical” physicalists claim. “Everything except qualia” reply the defenders of the Knowledge Argument. This thesis argues that both parties to this debate are committed to a traditional picture according to which one can tacitly adopt the standpoint of an off-stage narrator, capable of distinguishing ab initio between the different items in this conceptual scenario. The main claim here is that every time we artificially introduce a sharp conceptual distinction separating these two items or levels (mental and physical), we must automatically make a sophisticated conceptual leap in order to link the first-person qualitative perspective with the external physical world. Thus the physicalism/qualia dispute is only a by-product of an extended theoretical conception of the mind/world link which entails two distinct kinds of problems: (i) structural problems (to define and determine conceptually dual items like thought/matter, reason/senses, subject/object, etc.). Such problems require us to question “how are these items supposed to work together?” and this leads us to the second group of problems: (ii) mediation problems. The first group of problems inevitably leads to explanatory gaps; the second ends up needing to appeal to conceptual leaps in order to ensure the necessary link between two separate items. This exerts a powerful influence over the cast of our thoughts: seen from this angle, all philosophical enterprise comes down to the question of where to place the three following parameters: the world as it is, the conceptual picture which aims to represent the world as it is and the theorist-painter gifted with the ability to capture the world picture as it is. We also face the problem of finding the right mediators to assure coherence among the members of this trio, and the problem of setting the valid criteria guaranteeing the theorist-painter that what is captured on his conceptual canvas does indeed correspond to the world as it is, i.e. that he is not laboring under the delusions of an evil genie. In this thesis I argue against this way of putting things.

Diese Arbeit bewertet verschiedene Argumente, die nicht nur leugnen, dass Gehirnzustände und bewusste Zustände ein und dasselbe sind, sondern auch behaupten, dass eine solche Identität unverständlich bleibt. Ich argumentiere, dass keiner der Ansätze einen Physikalismus unterminieren, da sie für ihre stillschweigenden Annahmen über die Verbindung zwischen Arten der Präsentation und ihrer Erklärung keine direkte oder unabhängige Begründung liefern. Meiner Ansicht nach sollte die Intelligibilität psychologischer Identität nicht ausschließlich auf einer Meinungsanalyse basieren. Der Haupteinwand sollt dann sein, warum man annehmen sollte, dass eine vollständig intelligible Erklärung auf Beschreibungen der kausalen Rollen als Modi von Präsentationen beruhen sollte. Ich schlage dazu vor, den Blick auf “psychologische Konzepte” zu werfen. Psychologische Konzepte sind Konzepte, die eine Beschreibung von funktionalen Rollen benutzen aber von Erfahrungsqualitäten handeln. Ich schlage vor, diese in Qualitätsraum-Modellen zu analysieren um aufzuklären, warum von phänomenalen Konzepten erwartet wird, dass diese sich durch Beschreibungen der kausalen bzw. funktionalen Rollen auf etwas beziehen sollten. Der Qualitätsraum soll hier verstanden werden als multidimensionaler Raum, der aus mehreren Achsen relativer Ähnlichkeit und Unterschieden in den Anordnungsstrukturen verschiedener Modalitäten bewusster Erfahrung besteht. In meinem Vorschlag ist es möglich, dass einige Achsen des Qualitätsraumes selbst aus ihrem eigenen Qualitätsraum bestehen, so dass wir in die Beschreibungen der funktionalen Rollen “hinein zoomen” und “heraus zoomen” können und damit klarer sehen, wie die Erklärung eines bestimmten Bewusstseinsaspekts gestaltet ist, wenn man ihn in Begriffen psychologischer Konzepte betrachtet. / This thesis evaluates several powerful arguments that not only deny that brain states and conscious states are one and the same thing, but also claim that such an identity is unintelligible. I argue that these accounts do not undermine physicalism because they don’t provide any direct or independent justification for their tacit assumptions about a link between modes of presentation and explanation. In my view intelligibility of psychophysical identity should not be based exclusively on the analysis of meaning. The main concern then should be why expect that fully intelligible explanation must be based on the descriptions of the causal roles as modes of presentation. To this effect I propose that we examine "psychological concepts". The psychological concepts are concepts that use descriptions of the functional roles but are about qualities of our experiences. I propose to analyze them in quality space models in order to unveil why phenomenal concepts are expected to refer via descriptions of the causal or functional roles. The quality space should be understood here as a multidimensional space consisting of several axes of relative similarity and differences among the structures of ordering in different modalities of conscious experience. On my proposal it is possible that some axes in the quality space consist of their own quality spaces so we could “zoom in” and “zoom out” into the descriptions of the functional roles and see more clearly what the explanation of certain aspects of consciousness looks like when thought of in terms of psychological concepts.