JoeTheJuggler
Penultimate Amazing
- Joined
- Jun 7, 2006
- Messages
- 27,766
Define God. A formal, logical definition is a list of all characteristics that will include the objects you intend in the class "God" and exclude those you don't intend.Do you think the notion of God is logically contradictory?
I've yet to run into a well-formed definition of God that wasn't logically contradictory and/or abundantly, overwhelmingly contradictory with the empirical world.
Nope. Not at all. I understand fully the difference between possible and actual. The problem with Premise 1 is that it assume existence.Joe's main problem here is he's talking about modal logic without understanding the difference between actual worlds and possible worlds. In modal logic, there is a possible world where green unicorns live on Mars. That does not mean there are actually green unicorns on Mars. Just that it's a possibility. Under modal logic, anything that is not a logical contradication exists in a possible world. If the epistemic value of the proposition is between 0 and 1 (as in the case of the green unicorns), there's a possible world where that proposition is true (if the value is 1, then the proposition is true in all worlds).
When the weatherman says there is a 50% chance of rain tomorrow, this assumes the existence of rain. If he said there was a 50% chance of a ping-pong ball shower, it would assume the existence of ping-pong ball showers.
If you claimed there was a 1 in 5000 chance of there being unicorns on Mars, you're absolutely 100% without a doubt assuming the existence of unicorns. If unicorns did not exist, then the probability of them being anywhere is zero. Placing a value on that probability makes an assumption about their existence. If you use that assumption to "prove" their existence, the reasoning is circular. If you start with that as a premise--or a postulate or a given or a stipulated fact--and arrived at the conclusion that unicorns probably exist, your reasoning is circular.
Yes, fine. That's not the problem. The problem is that the conclusion in assumed in the premises (or postulates or givens or stipulated facts). If God is probable, then God is probable is a pointless, circular argument.So when someone makes the claim that God possibly exists, under modal logic, that claim would read there is a possible world where God exists. Once the possibility is established, you can then move on to Bayesian probability to argue how likely it is that something in a possible world exists in an actual world.
It's still circular. You can't predicate existence (that is, make "exists" part of the definition of something) and then use that to conclude that it exists without being circular. It's also an example of a validating argument. I can stipulate "necessary" into ANY concept and then "prove" it exists.As a side note, the ontological argument has a new formulation incorporating modal logic (this is very slick). Under this argument, God is defined as a necessary being (that is to say God has the property that it's non-existence is a logical contradiction).
