SLT Philosophy Lucy Marples 04.11.12 Perception What do we mean by perception? - A means of processing the world, using our 5 senses - Forming a mental picture of the world it s not simply a mish-mash of sensory data. We develop ideas and perceptions about what we are perceiving. Why is it so important? Epistemology (the theory of knowledge) asks where does our knowledge come from? - Two views on this are psychological nativism and empiricism - Psychological nativism holds that the mind produces ideas that are not derived from external sources/ the outside world. Plato was a proponent. - Empiricism holds that all knowledge comes from the senses, and we are born knowing nothing. A newborn is a blank slate ( tabula rasa ). Proponents: Hobbes, Locke, Hume. - This somewhat resembles the nature vs nurture debate - Positions at both ends are a bit absurd, but either way perception still seems highly important in the question of how we gain knowledge. Therefore, it makes sense to get clear on what we think is happening when we perceive something. If we suppose that some empiricist claims are true, what is the relationship between things in the world, and the images we have of them in our heads? FIRST THEORY OF PERCEVPTION: Naive/ common sense/ direct realism: - We perceive the world as it is
- The image in our heads matches reality - This is initially all very sensible sounding PROBLEMS FOR DIRECT REALISM: 1. Relativity of perception: different people and species have different perspectives. We might see the same object as being a different colour/shape. We have different sensory equipment (e.g. flies have different eyes to us, some of us are colour-blind). If what we perceive matches the world, and if we perceive the same things differently, how can this be? Are some of us wrong? 2. Hallucinations/dreams how can the world be exactly as we perceive it, if sometimes we perceive what is not there? 3. Sometimes we know we are not perceiving what is really there, and yet we still perceive it (McGurk effect) QUESTIONS FOR DISCUSSION 1. Do we have good reason to think that our perceptions show us exactly how the world is?
2. If yes: what about illusions, hallucinations, and differences in each other s perceptions? 3. If no: then can we really know anything about the world? SECOND THEORY OF PERCEPTION: representative realism - We don t perceive the real world, exactly as it is. - So what are we perceiving? Something else. What we are perceiving is separate and distinct from the real world. It is a representation of the real world. What reasons have we for believing in representational realism? - If we change the sensory data, we change the perception, without changing the real world.
- Scientific accounts of perception fit with this, e.g. astronomy we are actually seeing stars as they were millions of years ago, due to the time light takes to travel - It does seem that there are two different types of things: the object we are perceiving, and the perception of the object. Indirect realism tries to make sense of this difference - How would this theory account for the problems facing direct realism? PROBLEMS FOR INDIRECT REALISM: - If we are only ever perceiving representations, does this mean that we aren t ever able to directly perceive the real world? Are we stuck behind a veil of perception? Can we know anything about the external world? Do we even have any reason to think there is anything in the external world? (See Bishop Berkeley s Idealism) - Locke's view was that material objects have primary qualities like size, shape, and motion through space, but not secondary qualities like colour, smell, taste, and felt temperature; but does this mean that some perceptions are more real than others? Are we happy with this? What about e.g. the illusions at the end of the presentation aren t some of our colour perceptions more real than others? - What are the representations? Are they physical or mental, minddependent or mind independent? Do they only exist when they are being perceived? E.g. if a tree falls... - Berkley s objection to Locke: if primary qualities are more real, try and talk about them without talking about secondary qualities: how can I ever describe the primary qualities of an object, without talking about its secondary qualities. - Have we just moved the problem? i.e. if representations are mindindependent, how do we know we are perceiving them correctly. If they are mind-dependent, aren t we still at risk of being stuck behind a veil of perception?
QUESTION FOR DISCUSSION Are some perceptions more real than others? What is the difference? Does representative realism help us with the following illusions?