Philosophy 575 Prof. Clare Batty

The Argument from Illusion

1. The Argument from Illusion

1. If there sensibly appears to a subject to be something which possesses a particular sensible quality then there is something of which the subject is aware which does possess that quality. (Phenomenal Principle) 2(i) In illusion, there sensibly appears to a subject to be something which possesses a particular sensible quality when there is no suitable worldly object that possesses that quality. 2(h) In hallucination, there sensibly appears to a subject to be something which possesses a particular sensible quality when there is no suitable worldly object at all. C(i) In illusion, the something of which the subject is aware is not an everyday worldly object. It is a sense-datum. C(h) In hallucination, the something of which the subject is aware is not an everyday worldly object. C(1) In hallucination and illusion, subjects are aware of sense data 2. Phenomenologically indiscriminable perceptions, hallucinations and illusions have an underlying mental state in common. (Common Factor Principle) C(2) In veridical perception, subjects are aware of sense data.

Sense-data are the mental particulars of which we are aware in any perceptual experience. Think of a sense-datum as a ‘mental image’—although keep in mind that sense-datum theorists think that sense- data are the immediate objects of experience for all of the sensory modalities. So, ‘image’ is not the happiest way to put it. I look at a ripe tomato in normal conditions. The thing of which I am directly aware is not the tomato but a sense-datum. That sense-datum is red, round, etc. It has the sensible qualities that I (naively) attribute to the tomato.

2. Sense Data and the Two Hats

The phenomenological hat: You cannot do justice to what it is like to have an experience unless that experience actually involves an awareness of objects that bear the properties that characterize what it is like for the subject to have that experience. Is this right?

The epistemological hat: Now, what do/can we say about sense data theory if we don our epistemological hats?

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