1. GEORGE BERKELEY (1685-1753)

2. Protestant Irish; Bishop of Cloyne A key figure in British empiricism Developed a form of subjective idealism

3. Three basic positions in metaphysics: Materialism: Only matter is ultimately real. Idealism: Only mind is ultimately real. Dualism: Ultimate reality is both mental and material.

4. Two forms of idealism: Absolute idealism: ultimate reality is the Absolute, a sort of universal mind. Subjective idealism: ultimate reality consists of a multiplicity of minds (e.g. mine, yours, God's). This is Berkeley's view.

5. Berkeley's critique of matter (conceived of as something that exists independently of the mind): 1) The ordinary qualities of things can exist only in the mind—so if matter existed it would not have the qualities ordinarily attributed to it. 2) Matter is inconceivable (the 'Master Argument').

6. Berkeley's reasons for thinking that the ordinary qualities of things exist only in the mind include: Many qualities, such as heat and cold, often take a clearly experiential form (e.g. pain or pleasure); such sensations could only exist within a mind or minds. Perception depends on the observer: e.g. how hot an object feels to the hand depends not only on the state of the object but also on the state of the hand. Crucially, this applies as much to primary qualities as it does to secondary ones (e.g. things look smaller when further away).

7. The Master Argument: 1) Matter, by definition, exists independently of any mind. 2) But if we were able to conceive such a thing, we would be conceiving something existing unconceived. 3) The above is a contradiction (a 'manifest repugnancy') and so the concept of matter should be rejected as incoherent.

8. Response to the Master Argument: There is a difference between: (A) 'We conceive of x and we do not conceive of x' and: (B) 'We conceive that [x exists though we do not conceive of x]'. (A) is a contradiction but (B) is not.

9. What about unperceived objects? There was a young man who said "God Must find it exceedingly odd To think that the tree Should continue to be When there's no one about in the quad."

10. The reply: "Dear Sir: Your astonishment's odd; I am always about in the quad. And that's why the tree Will continue to be Since observed by Yours faithfully, God."

11. Berkeley really has two answers to the 'problem of unperceived objects': 1) The metaphysical answer—since God perceives everything, there are in reality no unperceived objects. 2) The analytical answer—unperceived objects exist as (in the phrase of J.S. Mill) 'permanent possibilities of sensation' (the phenomenalist view).

12. Berkeley's ontology (theory of what there is): Ideas (things perceived or thought of). Spirits (the beings that perceive or think of them). Note: spirits are also endowed with volition (will): they can cause ideas to exist.

13. www.philosophyadvice.net Click on 'A' level philosophy files to find: Berkeley (these slides) Perception (a guide)