A long time favourite thrown up by the theists is Anselm's Ontological argument. Anselm lived between 1033 and 1109 so as usual, were dealing with the logic of a theologian who lived in century far different from our own. What's the point of making that observation? Well, the sort of argument and evidence he deploys is situated in a context where it probably made a lot more sense. Despite this they are drawn wholesale into a new cultural milieu with the expectation that they still hold a profound measure of validity.
Basic summary:
1- we can conceive of a greatest possible being (defined as omniscient, omnipotent, and morally perfect)
2- existence in reality is greater than existence in the mind
3- the greatest possible being must then exist otherwise it wouldn't be the greatest possible being
4- therefore, God exists
While Anselm admitted that we cannot know everything about God, he believed we can know enough to know that He is the greatest possible being and once we recognise this it would impossible to deny that being exists. Sounds rather like his position was, "until you believe in the God I believe in, you will continue to deny His existence." Presumably Anselm's belief in God prompted his formulation of the argument, and so it isn't the product of any actual attempt to prove God's existence per se; more accurately it could be described as a validation of existing convictions. Our old friend circular reasoning.
Returning to the claim that we can have sufficient knowledge of God to know He is the greatest possible being: this assertion ignores the possibility that what we know could lead to the opposite conclusion (i.e. God is flawed). Famously, a monk by the name of Gaunilo challenged Anselm in his own time by using the same structure to demonstrate the reality of non-existent things (his example was the 'perfect island'). While this deployment of Anselm's logic is supposedly mistaken as the object in question must be one with qualities that have an "intrinsic maximum".
But does the greatest possible being possess only attributes with an "intrinsic maximum"? For example, who defines the limits of 'moral perfection'? This is a good point to segue into the problem or evil which I'll visit in the next post, but for the moment it suffices to say that one man's omnipotence is another man's limitation:
To quote that profound modern day philosopher, Homer Simpson:
"Could Jesus microwave a burrito so hot that he himself could not eat it?"
This is only part one of my continuing observation on the inherent flaws of the ontological argument. And even at this nascent stage the self-contradiction is eveident: if you already believe then this might look like convincing proof, but if you believe you don't need proof.
A being that exists may be better than one who doesn't; however, an argument that offers actual proof is infinetly greater than one that just claims to.