Compare the strengths and weaknesses of direct and representative realism
Direct realism is the position that we directly perceive reality. This means that how we see, hear, taste, feel and smell the world is exactly how it is in the opinion of a direct realist. For example, if we see the grass as green, then this must mean that the grass has to be green. However there are problems with this claim. For example, if we put our thumb next to the moon, and close one eye, our thumb appears to be bigger than the moon. We know this is not the case because of the distance of the two objects. This is where representative realism comes into play.
Representative realism is when we perceive and object through our sense data; we see, hear, smell, feel or taste an object and interpret this through our sense data to create a perception of the world of physical objects. For example, when we see a stick in water, it appears bent. This is an illusion and we understand this because we analyse it with our sense data. This gives representative realism an advantage over direct realism, as direct realists would say that the stick must be bent.
What can also help separate these two positions is Locke's idea of primary and secondary qualities. Locke suggested that there was a difference between our perception and reality, and he states that our ideas of objects are through our understanding of these qualities. Primary qualities, according to Locke, are qualities that are inherent to an object; for example a primary quality could be the shape, size or state of an object. The primary qualities we perceive resemble the primary qualities of the physical object, and are therefore independent from our perception. Secondary qualities however are qualities that can exist separately from the physical object and are dependent on our perception. These are things such as colour, distance, feel, smell, taste and sound of the object. These secondary qualities of the object do not resemble the object in any sense, for example 'redness' is a frequency of colour perceived through our sense data, and therefore not an inherent quality of the physical object itself. This would mean that the stronger argument would be representative