Phenomenalism versus physicalism in colour and space perception
Since Locke introduced the distinction between primary and secondary qualities, the controversy on the ontological status of colours has never abated. Many philosophers (Frank Jackson, Mark Johnston, D.M. Armstrong, Christopher Peacocke, ...) still debate whether colours are mental or physical, pure sensations or concepts, qualities or dispositions. However, the traditional philosophical debate is dissatisfactory because in most cases an empirical background is missing.
In recent years, especially after the publication of Hardin's Color for Philosophers, the use of empirical data has become more important, as in the work of Jonathan Westphal, Austen Clark, Don Dedrick, David Hilbert, Evan Thompson. Their philosophical position is based on empirical results from various disciplines, and their work is a philosophical elaboration of ideas that are latent in colour science. Many of these ideas are not tenable, as has been convincingly demonstrated in the work of Saunders and van Brakel. Saunders and van Brakel deny the existence of basic colour terms, criticise the idea of a unique phenomenal colour space, and undermine the theory of opponent processes. These 'theories' are remnants of ideas that were universally accepted at the end of the nineteenth century (e.g., in the work of Hering, Ostwald, Munsell, etc.).
In the proposed project, I intend to analyse how traditional ideas on colour both in philosophy and in colour science, are remnants of obsolete scientific theories. Subsequently, I want to assess the ontological status of colours in the light of modern scientific data. This will result in a new (and more scattered) conception of colour and colour perception. Both the historical and the modern empirical part will throw a new light on the gap between a phenomenal and a physical characterisation of colours. This inquiry is interesting for philosophy of science, because by means of a single subject (colour), paradigms and explanatory models in different sciences can be compared. There is a notable incommensurability between the phenomenal and the physical point of view. Moreover, the fact that colours can be experiences or physical objects (or brain states) seems to contradict a strong scientific reductionism.
Looking at the development of colour science, one readily sees that there has never really been a good concept of colour. The controversy between Goethe and Newton's followers is well-known (and adequately described by Dennis Sepper). Since the beginning of the nineteenth century there has been a growing interest in colour perception. Young, Grassmann, Maxwell, von Helmholtz, Mach, Ostwald, and later Schr�dinger have come up with interesting results. Most of these scientists combined research in physics, chemistry or logic, with research in psychology or physiology, which resulted in a rather physicalistic conception of colour. In the last decades of the nineteenth century, there was a growing interest in psychology too, with work of, among others, Hering and Ebbinghaus. Introspection, or the phenomenal point of view, became more important. Because of the invention of spectrometers, and the economical needs for standardisation of colours, there has been a real boom in colour science in the first half of the twentieth century. When fixing the CIE-conventions (standard observer, standard daylight,...) in the twenties and thirties, physicists and psychologists were constantly in conflict. In brief, the development of colour science was marked by a continued tension between the phenomenal/psychological perspective and a physical conception of colours. The complete division of the various scientific disciplines, in which colours are studied, can be regarded as a means of 'taming' the tension..
This historical background will allow a better assessment of the present situation in colour science and philosophy of colour. Some widespread ideas can easily be traced back historically, but are based on almost no empirical evidence. A clear example is the case of the phenomenal colour space. The idea is present in the work of Goethe, Ostwald, and Munsell. Many researchers in colour science have in vain tried to provide a best fit of the phenomenal colour space. As follows from my recent research, the only reliable colour spaces are physical spaces, characterised by physical parameters. Attempts to find a physical colour space that is isomorphic with the phenomenal colour space are misguided. The ubiquity of the phenomenal colour space can only be explained historically. Though the core of my critique on the idea of a phenomenal colour space has appeared in a few publications, the empirical and historical analysis can be improved, and some philosophical consequences still need to be worked out. Colour experiences, and the relations between them, must be identified in new ways, and identification by means of their location in the phenomenal colour space is no longer possible. This has implications for the inverse spectrum thought-experiment, as the solution of invoking the asymmetry of the phenomenal colour space is no longer tenable.
Another example of a theory with little empirical support, is the theory of opponent process based on ideas of Hering (and Goethe), and revitalised by Hurvich, Jameson, and De Valois. From a physical/physiological point of view, one can say that visual information is processed by means of opponent cells in the retina, which react to local colour variations. From the phenomenal point of view, one has 'pure colours' (e.g. red), and 'impossible combinations of colours' (e.g. greenish-red). The two are combined in Hurvich' theory. However, this is only a hypothetical scheme. It is not clear at all how to implement it physiologically. The physical/physiological and the phenomenal sides are less easily combined than is generally accepted. A careful scrutiny is necessary to obtain a more adequate view on colour. Disentangling the theory of opponent processes will put pressure on the idea of pure colours. This will lead to further support of van Brakel and Saunders' anti-essentialist thesis on colour categorisation.
After the historical and critical part, there will be a more constructive part, in which I want to sketch a modern view on colour in an interdisciplinary context. Science on colours has fallen apart into various distinct research disciplines like physics, psychology, anthropology, linguistics, physiology, neurology, chemistry, computer science, history of science, ... There is, surprisingly, little interaction between the various disciplines, so that there is scarcely any critical reflection of current ideas on colour and colour perception. This is an interesting situation for philosophers, because it leaves much room for the construction of a modern picture on colour.
On analogy with the case of colour perception, I will investigate the nature of space perception. A similar tension between the phenomenal and the physical perspective is at work. The problems related to the phenomenal colour space appear in a similar form in space perception (Derksen, Heelan, Shepard). This will lead to an analysis of the nature of internal representations.
In addition to this work that concentrates on non-reductionism concerning internal representations, I want to elaborate some themes related to Quine's philosophy, which was the subject of my Ph.D. thesis, in the context of congresses or invitations. These themes concern rationality, non-reductionism and history of naturalism.