Introduction to Philosophy Instructor: Jason Sheley
Quiz: True or False? (if false, explain why) 1. Descartes investigates whether there is a God because he needs to rule out a source for his doubts concerning what he knows. 2. Descartes believes that we know the Sun best of all by means of the senses. 3. Part of Descartes' proof of God's existence is that there must be at least as much reality in the cause of his idea, as there is in what the idea represents. 4. Descartes thinks it is possible he could come to the conclusion that he is in fact God, and thus the source of his idea of God. 5. Descartes concludes that the idea he has of God is innate (something he was born with). 6. Descartes thinks the source of his errors is his limited intellect.
Today s warm-up: How does Descartes prove God s existence in Meditation 3? (See if you can reconstruct the argument without looking at your notes...)
Meditation 5
Now that Descartes has arrived at the CDP Rule, he next investigates what he knows in a clear and distinct way. The first candidate is mathematical truths.
Next, Descartes considers God again. And at this point, he gives yet another proof for God s existence. Let s look at the text on this one...
Since in all other matters I have become accustomed to distinguishing existence from essence, I easily convince myself that it can even be separated from God s essence, and hence that God can be thought of as not existing...
But nevertheless, it is obvious to anyone who pays close attention that existence can no more be separated from God s essence than its having three angles equal to two right angles can be separated from the essence of a triangle, or than that the idea of a valley can be separated from the idea of a mountain. Thus it is no less contradictory to think of God (that is, a supremely perfect being) lacking existence (that is, lacking some perfection) than it is to think of a mountain without a valley.
Is this proof of God s existence any better than the one we encountered in Meditation 3? (Hint: notice what Descartes says about trying to think of God without existing...)
For I am indeed of such a nature that, while I perceive something very clearly and distinctly, I cannot help believing it to be true. Nevertheless, my nature is also such that I cannot focus my mental gaze always on the same thing, so as to perceive it clearly.... thus, other arguments can be brought forward that would easily make me change ompare Plato my opinion, were I ignorant of God. And thus I would never have true and certain knowledge about anything, but merely fickle and changeable opinions.
Descartes says that his knowledge of God s existence enables him to put trust in anything that he can clearly and distinctly perceive as true. And this will allow him to do a great many things.
One question remains at the end of Meditation 5: has Descartes managed to get himself out of the circle? God Exists Anything he CDP is true Descartes CDP that God Exists
Traditional Arguments Concerning the Existence of God
Ontological Arguments http://plato.stanford.edu/entries/ontological-arguments/
Anselm of Canterbury I conceive of a being than which no greater can be conceived. If a being than which no greater can be conceived does not exist, then I can conceive of a being greater than a being than which no greater can be conceived namely, a being than which no greater can be conceived that exists. I cannot conceive of a being greater than a being than which no greater can be conceived. Hence, a being than which no greater can be conceived exists.
Guanillo's Reply 1. The Lost Island is that than which no greater can be conceived. 2. It is greater to exist in reality than merely as an idea. 3. If the Lost Island does not exist, one can conceive of an even greater island, that is one that does exist. 4. Therefore, the Lost Island exists in reality. http://en.wikipedia.org/wiki/gaunilo_of_marmoutiers
From the Stanford Encyclopedia God is a being which has every perfection. (This is true as a matter of definition.) Existence is a perfection. Hence God exists. It is possible that that God exists. God is not a contingent being, i.e., either it is not possible that God exists, or it is necessary that God exists. Hence, it is necessary that God exists. Hence, God exists.
Alternative schemes
Maimonides There is no oneness at all except in believing that there is one simple essence in which there is no complexity or multiplicity of notions, but one notion only; so that from whatever angle you regard it and from whatever point of view you consider it, you will find that it is one, not divided in any way and by any cause into two notions
Maimonides thought, therefore, that we can say THAT God exists. We cannot, however, say what God is like. We can only say what God is NOT like.
Epicurus Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?
First of all, people should believe that god is blessed and indestructible (p. 28) but god is not as the many make it out to be (which is based on false presuppositions)
Overall conclusion: So death, the most frightening of bad things, is nothing to us; since when we exist death is not yet present, and when death is present, we do not exist. Therefore, it is relevant neither to the living nor to the dead, since it does not affect the former, and the latter do not exist. (p. 29)
Compare with Plato (Phaedo): But the wise man neither rejects life nor fears death. For living does not offend him, nor does he believe not living to be something bad. And just as he does not unconditionally choose the largest amount of food but the most pleasant, so he savors not the longest time but the most pleasant. (Letter to Menoeceus, p. 29)
For there is nothing fearful in life for one who has grasped that there is nothing fearful in the absence of life... (p.29)
George Berkeley
To exist is to be perceived
Argument A 1) Bodies are collections of ideas. 2) If bodies are collections of ideas, then we can know the existence of bodies. C) Therefore, we can know the existence of bodies.
Argument B We know the existence of bodies. If we know the existence of bodies, then bodies are collections of ideas. Therefore, bodies are collections of ideas.
Argument B might appeal to Berkeley, since he seeks to defend common sense. Argument A, on the other hand, is a refutation of skepticism.
1 sensible things cannot exist otherwise but in a mind or spirit. 2 the existence of sensible things does not depend on me. C) therefore, sensible things must exist in some other mind.
How does Berkeley's proof of God's existence go?
The 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." "Dear Sir: Your astonishment's odd: I am always about in the Quad. And that's why the tree Continues to be, Since observed by, Yours faithfully, God."