Jonathan Westphal

Das „Problem der Induktion", dessen Formulierung man gewöhnlich David Hume zuschreibt, hat Leibniz schon am Anfang des 18. Jahrhunderts formuliert und gelöst. Die Methode von Leibniz war sowohl „Hume-isch" als auch rationalistisch. Sie begreift in sich eine Herabsetzung des Empirischen und auch den Gebrauch der „Geheimkräfte", die Hume ausschalten wollte. Ohne solche „Geheimkräfte" gibt es keine Harmonie im klassischen Sinn von Leibniz . Für Leibniz ist eine Hypothese vorzuziehen, die eine Harmonie behauptet oder die maximale Verschiedenheit der Phänomene mit der minimalen Kompliziertheit der zugrundeliegenden Regel zusammenfaßt. Hier sind Beispiele von Gesetzen mit „produktiven Mechanismen" oder „Geheimkräften" gegeben, die der Leibnizschen Erklärung in der Physik und der Mathematik entsprechen. Die Schwerkraft entspricht diesen Gesichtspunkten nicht und ist daher unvernünftig im Leibnizschen Sinne; deshalb werden Induktionen über Schwerkraftsysteme als empirische Regeln betrachtet. Die Leibnizsche Theorie zeigt auch, wie man die wohlbekannten Beispiele von Hume erkennen und vorhersagen kann, nämlich aufgrund des richtigen wissenschaftlichen Verständnisses der Natur der Nahrung und des Feuers. Kants Prinzip der zeitlichen Reihenfolge wird zu seinen Ungunsten mit dem sechsten Grundsatz der Leibnizschen Abhandlung über die Metaphysik verglichen. Wir haben nach Leibniz doch einen vernünftigen Zugang zu der Wirklichkeit, die hinter den Empfindungen liegt, und die Verneinung dessen war es, was das empiristische Problem der Induktion erzeugt hat. Das Problem der Induktion ist ein reductio ad absurdum des Empirismus

In Remarks on Colour Wittgenstein discusses a number of puzzling propositions about brown, e.g. that it cannot be pure and that there cannot be a brown light. He does not actually answer the questions he asks, and the status of his projected ?logic of colour concepts? remains unclear. I offer a real definition of brown from which the puzzle propositions follow logically. It is based on two experiments from Helmholtz. Brown is shown to be logically complex in the sense that the concept of brown can be ?unpacked? or resolved into simpler concepts. If my solutions to Wittgenstein's puzzles are the right ones, then science does bear upon the ?logic of colour concepts?, and the contrast between logic and science which Wittgenstein sets up is a false one. At best it will appear as the contrast between the demands of logic and the demands of a particular kind of scientific theory and a particular mode of scientific theorizing. The solutions to the puzzles about brown are distinguished from psychological explanations, and the paper ends by suggesting what it was in his own doctrine that prevented Wittgenstein from answering the questions he had set himself

We wish to defend Jonathan Westphal's view that colour is complex against a recent ‘phenomenological’ criticism of Eric Rubenstein. There is often thought to be a conflict between two kinds of determinants of colour, physical and phenomenal. On the one hand there are the complex physical facts about colour, such as the determination of a surface colour by an absorption spectrum. There is also, however, the fact that the apparently simple phenomenological quality of what is seen is a function of the physiological and psychological state of the viewing subject. Should the physical trump the phenomenal, or is it the other way round? Much of the phenomenal variation of colour, however, is explained by physical facts. There is a physics and a psychophysics of colour. Colours appear, to the colour scientists at least, to be in some sense objective, a sense not explained by the view that they are purely phenomenal. Taking physics and psychophysics into account will mean rejecting the claim that the content of what our concepts of colours are concepts of is exhausted by the purely phenomenal, or that we can determine these concepts simply by gazing at a colour. Taking account of physics will lead, as Westphal argued, instead to a view about white and the other colour terms like Putnam's account of gold. Necessary truths about colours cannot be explained without reference to the logic of the compossibility of what is given in reflection and absorption spectra, the analogue of H2O.

Parts I and II of 'Conflicting Appearances, Necessity and the Irreducibility of Propositions about Colours' review the argument from 'conflicting appearances' for the view that nothing has any one colour. I take further a well-known criticism of the argument made by Austin and Burnyeat. In Part III I undertake the task of positive construction, offering a theory of what it is that all things coloured a particular colour have in common. I end, in Part IV, by arguing that the resulting 'colour phenomenalism', rather than physicalism, is required to give a satisfactory account of the necessity of Wittgenstein's 'puzzle propositions' about colour

Many philosophers have believed that colours and the other qualia ofexperience are simples and that colour terms are unanalysable. Colour termsare unanalysable because colours are simples, colours are known to be simple because colour terms are unanalysable. I shall try to show that things are not as simple as this. Nothing in the paper will depend on the general Wittgensteinian thesis of the relativity of simplicity. The thought I shallpursue is the more specific one that the philosophers who have believed in the simplicity of colours have been the victims of certain false images of what the relevant kind of simplicity is like, and that when these images are destroyed the belief is clearly false. Most importantly they have confused logical simplicity with visual uniformity, the kind of simplicity which could intelligibly be attributed to coloured patches or expanses of colour andthe kind of simplicity which can be attributed to colours. So the paper is concerned with the destruction of spatial and material images which distort our understanding of concepts which are neither spatial nor material ones.The wider epistemological implications of the non-existence of simple ideas of colours will not be discussed

This chapter focuses on the incompatibility of afterimage colors. Several quasilogical, semantic, and metaphysical questions having to do with incompatibility come up in color theory, and the problem is so complicated and fragile that it is argued here that, despite some marvelous work on the topic, the problem remains to be sorted out. Every naive subject who encounters afterimages without prejudice has agreed that they have color; this is mentioned here because it is the initial and also the commonsense view. However, accepting that a physical account of color incompatibility is right for physical colors makes an account for the incompatibility of afterimage colors improbable. One can provide a physiological account based on opponent processes, but this will deliver only a contingent truth or a necessity relative only to a particular retinal structure and postretinal neural coding.

Dans la première méditation, Descartes a conclu, en regard des songes, « qu'il n'y a point d'indices concluants, ni de marques assez certaines par où l'on puisse distinguer nettement la veille d'avec la sommeil [...] » . À la fin de la sixième méditation, il a conclu qu'il y a de tels indices, mais qu'on a besoin de la garantie de Dieu pour savoir si ces indices sont réellement des indices de la veille. Cottingham a proposé une objection générale contre tels indices de la veille: On peut rêver cet indice. Selon les raisonnements de Cottingham, il s'agit de l'existence de l'indice. Or, chez Leibniz et Descartes il ne s'agit pas de cela, mais il est question de savoir si l'indice est vraiment un indice de la veille. La prétention que l'indice puisse être présent en songe fait une pétition de principe. Notre examen des indices que Leibniz et Berkeley ont proposés révèle cette pétition