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Funded by: John Templeton Foundation
Main contact: Dr Stephen Leuenberger, Prof. Fiona Macpherson
Start date: 2016
End date: 2017
Principal Investigators: Fiona MacPherson and Stephan Leuenberger
Postdoctoral Researcher: Umut Baysan
A common-sense view is that when we perceive physical objects—tables and chairs—we simply become aware of those things and their properties. We become aware of a table and its squareness, a chair and its brownness. However, illusions and hallucinations have led some philosophers to doubt this. In illusion you misperceive an object. For example, you might perceive a table but experience it to be round when it is actually square. Or you might experience a chair as being red when it is really brown. In hallucination it seems to you as if you are perceiving an object, but you are not. For example, you might hallucinate that there is a table in front of you, when there is not.
Some philosophers think that in illusion and hallucination you are aware of objects and properties—but those objects and properties are not the ones that surround you in the physical world. Instead, you are aware of mental objects and properties called “sense-data” that exist only in the mind. Moreover, many philosophers who endorse sense-data believe that even when we are veridically perceiving we are aware of sense-data. In illusions and hallucinations sense-data (usually) mislead us about the world. But in veridical perception they accurately tell us about the physical objects—tables and chairs—around us in the world. But we are aware of those physical objects only indirectly, in virtue of being directly aware of sense-data.
Sense-data theory is rejected by many philosophers because it posits mental entities—entities that are usually taken to be non-physical. Such a view contradicts physicalism, understood as the view that everything about the mind can be explained in terms of broadly physical entities. However, we believe that this is not sufficient motivation to abandon sense-data theory. One reason is that it is not evident that physicalism is true. We shouldn’t reject sense-data theory if it turns out to be a good theory of perceptual experience, given that good theories of it are hard to find, but consider questioning physicalism instead. Moreover, it has not been demonstrated that sense-data theory is incompatible with physicalism. That an entity is mental does not alone entail that it is not also physical. If the mind is dependent on the brain, and the brain is physical, then might not sense-data be physical too? One main aim of this project is to understand the metaphysical commitments of sense-data theory utilising recent developments in metaphysics about what dependence and fundamentality are.
We will also investigate whether sense-data theory gives a good account of all illusions and hallucinations. One reason to think that it does not is the alleged existence of illusions where subjects experience objects with contradictory properties (such as moving yet not changing position). If sense-data are as they appear to be, then such illusions or hallucinations imply the existence of impossible objects. But surely impossible objects cannot exist—that’s why they are impossible! We take this to be a serious challenge to sense-data theory. Our explorations will lead us to examine the ways properties such as space, time and motion are represented in our experience, drawing on the latest scientific results about illusions and hallucinations, and on philosophical reflection on the structure of experience. We will study the sense-data theory focusing on (1) whether it is phenomenologically adequate and (2) what exactly the metaphysical commitments of the theory are. We will do this by investigating the nature of experience with respect to perception of space, time and motion, and by exploiting recent advancements in metaphysics.
Activities and Timetable
The project will run from 1 July 2016 for one year. Core project members will meet fortnightly, together with selected faculty and graduate students at Glasgow’s Centre for the Study of Perceptual Experience (CSPE). We will discuss our developing work and the extant literature. Affiliates will join when available. Umut Baysan will organise a workshop on sense-data in April 2017. Members of the project will make short visits to the labs of our affiliates, from whom we have invitations, and to the New Directions Project at Cambridge, and affiliates will make short visits to Glasgow.
Image Credit: Between a Thing and a Thought, Susan Aldworth, collagraph print, 2000. Image courtesy of the artist and GV Art Gallery, London