My absolute favourite philosophical argument ever comes from Anselm of Canterbury. Way back in the 11th Century Anselm argued in
Monologion and
Proslogion for the existence of God using
a priori reasoning alone. I took a small extract from one of my 3rd year essays and edited out the complex bits and the less interesting technical logic-y bits in it. Here is Anselms argument and the most famous objection to the argument from Gaunilo:
Anselm’s argument is best understood when set out in logical form as so:
P1 God is ‘that than which nothing greater can be thought’.
P2 Something that exists in reality is greater (
Cēterīs paribus) than something that exists in the understanding alone.
P3 If God exists in the understanding alone then we can imagine something greater than God.
P4 God must necessarily exist in reality because otherwise he would not be ‘that than which nothing greater can thought’.
C God exists in reality.
If we accept premises 1-4 so far, then, it appears we must concede that God exists as Anselm’s conclusion follows validly from its premises’. However numerous criticisms have been aimed at Anselm’s argument by attacking the premise’s, perhaps the most famous objection coming from Gaunilo.
Gaunilo worried that Anselm was, as the objection is often put, ‘defining something into existence’ which seems suspicious, as, if Anselm’s argument is correct then we may be able to use this line of reasoning to define other things into existence. Gaunilo attempted to show exactly this. He wrote to Anselm asking him to imagine a perfect island one which is ‘that than which nothing greater can be thought’. To be the perfect Island, according to Gaunilo, the island would have to be more excellent than all other islands, and in order to achieve this it would have to exist in reality rather than just in the mind alone, as an imaginary island would not be the most excellent island. Gaunilo hoped his perfect island example would force Anselm to retract or change his argument.
Unfortunately for Gaunilo, perfect islands do not have the same defining characteristics as God. Things that make an island great may be palm trees or white sand, but palm trees and white sand are certainly not the kind of features Anselm claims God has. With the example of the perfect island there will always be something else we can add to it to make it more perfect. For example, we can continue adding another grain of sand for an infinite amount of time, thus making Gaunilo’s island incoherent. This is exactly what C.D Broad claims.
Broad argued that for something to be the greatest possible being (or in Gaunilo’s case island) there has to be an upper limit, or maximum value to the features ascribed to the being (or island). If this is not the case then it is meaningless to talk of such a being. In Anselm’s case God does have maximal limits, for example if he is omnipotent then it is impossible for him to know any more than knowing all and knowing all true propositions. However in Gaunilo’s case the perfect island does not have intrinsic maximal limits, we can always add one more lake, coconut, grain of sand etc… Because islands don’t have an intrinsic maximal limits Gaunilo’s criticism of Anselm’s ontological argument could be seen as invalid and not as damaging to Anselm’s argument as they initially appear.
I could chat on for hours about the hundreds of rebuttals and objections one can make against Anselm but I can't be bothered right now, plus it would probably be boring for anyone who isn't me. I think one of the main reasons why I love this argument so much is it's simplicity. When I first heard it I was convinced by it. Perhaps this is why I love it so much, no other arguments I have come across in philosophy have actaully made me change my views so radically, even if Anselms argument only convinced me for about a minute.
