From Subjective Idealism to SkepticismBerkeley & HumeGeorge Berkeley (pronounced /ˈbɑrkli/ ) (12 March 1685 –14 January 1753), also known as Bishop Berkeley (Bishop of Cloyne), was an Irish philosopher whose primary achievement was the advancement of a theory he called "immaterialism" (later referred to as "subjective idealism" by others). Berkeley lived in Ireland, worked for a short time in Bermuda and in Rhode Island then returned to England. He was concerned about a number of issues of his time which included literacy among native populations and the welfare of abandoned children. Interestingly, though his philosophical contributions are what he is most remembered for today, during his lifetime, his best selling work was on the medicinal qualities of pine tar!Berkeley Rejects Materialism:  Berkeley rejected Locke’s distinction between primary and secondary qualities of perception: For Berkeley, all perception is secondary. “But it is evident…, that extension, figure, and motion are only ideas existing in the mind and that an idea can be like nothing but another idea….” (p.189) Having rejected Locke’s distinction, Berkeley further argued we cannot claim to know a thing as an independently existing material object - this is the bizarre invention of philosophers – as far as we can know, things are only the ideas we have of them. For Berkeley - there were only minds and ideas in the mind. “…it is possible we might be affected with all the ideas we have now, though there were no bodies existing without, resembling them.” (p. 191)Berkeley’s Subjective Idealism: P1) Our objects of knowledge are limited to 3 kinds of ideas ideas from senses ideas from passions ideas from memory P2) There must be something distinct from these ideas & perceptions which is the perceiver’s mind (like Descartes’ “Cogito ergo sum”)  P3) There is no proof for ideas existing outside of the mind______________________________ C) Therefore a thing can exist only in the mind. –“Esse est percipi” -To be is to be perceived (p.188)Berkeley’s Subjective Idealism  “Esse est percipi” implies that existence is entirely composed of immaterial ideas We do have some knowledge which is not derived from sense data – Berkeley calls these things Notions - such as the notion of our own existence and the existence of God.  Berkeley is faced with the same problem Locke pointed out: that we can’t just wish things into or out of existence. If existence is just the universe of the ideas and notions in our minds, then why wouldn’t we control this universe through thought? Berkeley’s answer is because there is a greater mind which controls this universe of ideas. His "proof" for the existence of God is as follows:Berkeley’s Argument for the Existence of God:P1) Ideas that we are aware of do not depend on our wishesP2) if they P1 is true these ideas must have some kind of existence apart from our mindsP3) if we are not responsible for the ideas we perceive and cannot control all our ideas at will there must be some other mind that possesses, controls and maintains the ideasP4) this other mind must be independent from and greater than ours - "a universal mind" or GodP5) these ideas exist_____________________________________________C) God must existGod as the Universal Mind: The introduction of the existence of God - or the Universal Mind is crucial for Berkeley's thesis - It is God which orders our perceptions and grants us some sense of continuity - God allows for the things we perceive to exist distinct from us  Through his use of God, Berkeley avoids the problem of our just being able to "think" things into existence and the problem of the world disappearing if no human is perceiving it a any given time. We do not choose what to perceive - there is some other "will or spirit" which produces these sensations (p.192) This will or spirit is constantly perceiving the world so it is constant outside of human perception - it doesn't just go away if no one looks at it.Berkeley’s Reality: God’s universe – the real universe of all existing ideas is represented by set A.  Our universe is the subset intersection between our mind and God’s mind (A & B) “The ideas imprinted on the senses by the author of nature are called real things….” (p. 193) Nothing outside of God’s universe can be known to exist (B) except as ideas we have formed through our imagination and fantasy.Ronald Knox’s Limerick: There was a young man who said, "God Must think it exceedingly odd, If he finds that this tree Continues to be When there's no one about in the Quad." 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."What would Berkeley say about The Matrix? http://www.youtube.com/watch?v=UM5yepZ21pIA Quick Comparison: Berkeley = Locke – the independently existing material object + God Berkeley agrees with Locke about empirical data being the foundation of knowledge but rejects the material world as the cause of our sensations and perceptions. Hume = Berkeley – God Hume agrees with Locke about perception as the foundation of our ideas, and with Berkeley that we cannot justifiably make a distinction between primary and secondary qualities of perception but disagrees with Berkeley about God as the universal mind controlling those perceptions.David Hume Biographical Notes: Hume is known both as "The Congenial Skeptic" as well as "The Scottish Heretic" - He earned his living as a writer and an under-secretary to the British Embassy in Paris during the mid- to late-1700's. Because of his "heretical" views he was refused a professorship in the major universities. (7 May 1711 – 25 August 1776)Hume’s Skepticism Hume accepted Locke's Empirical Method but he rejected any knowledge claims outside of clear experiential basis. Hume argued that the realm of human knowledge was limited to impressions and ideas - all other was in the realm of those things unknowable - and, for us, as far as we can know, they simply don't exist. This implies that Berkeley’s “universal mind” or God could also be a subjective idea that we hold. Instead of our ideas depending on God, Hume argues that we cannot claim to know that it is impossible for God’s existence to