Here's a link to Randal's blog: http://randalrauser.com/2017/10/claim-believing-god-exists-necessity-defining-god-existence/
Read it, then read it again. I admit I have some problems with Randal's reductio (I don't think it works), but it got me thinking, and I think we're at least closer to a point of understanding, which has to be a good thing.
Randal puts forward a view of a "theistic belief set" (TBS) that needs to be countered:
- God exists
- God's existence is necessary
Now here is where I thought I saw a problem - in order to argue with these points, Randal seems to be suggesting that anyone (atheist or other-theist) who counters either one of these is somehow missing his TBS - Randal's TBS is constructed to be immune from criticism (bear with me here - this is me trying to puzzle this stuff out).
So if I as a philosophical greenhorn say that Randal doesn't in fact know that his God exists, he can point to section 2, and say that God's existence is necessary. If I say that God's existence isn't necessary, he can simply contend that I don't understand philosophy and make some strange remarks about my mountain bike.
This seems very odd - how can intelligent people end up so divided? Well, I'm not a philosopher, and I use "necessary" in an everyday sense - it's certainly possible that I'm missing a technical/jargon usage, and maybe Randal isn't saying what I think he's saying. Let's look at that - perhaps by laying out my naive understanding of the terminology, it may help clear my befuddled head. Fortunately Randal has done a lot of the work for us here.
We'll start with a BRUTE FACT. To me (and no doubt Randal or someone will correct me if I'm wrong), this means something that can be stated as "it just is" and nobody in their right mind would contradict it. The world exists. Brute fact. There we go. It's just there, no argument. Fine. I'm happy with this (I understand hard-core philosophers can have hours of fun on this point, but we'll leave them to it for now).
Then there are CONTINGENT facts. This seems to entail a form of existence that depends on other things existing first. This blog post exists, contingent on me having written it, and the internet existing on which to host it. It's a brute fact (because here it is!), but is contingent on the existence of other things. So contingent and brute are not exclusive categories.
Now here is my new understanding (and, yes, maybe I'm still getting this wrong): NECESSARY existence may be a form of existence that is REQUIRED or INEVITABLE in order to explain the existence of CONTINGENT things. In other words, NECESSARY existence stands in a prior relationship to things that exist contingently upon it.
This does make Randal's appeal to the necessary existence of integers (in the twitter thread) seem rather odd. I would say he's right in that we can't avoid the existence of integers, but it's not that they exist "necessarily" in the way we have just explored above. They seem to have a different form of existence in whatever way Platonic things can be said to exist. My head now hurts, so let's pretend for the moment that this is not relevant.
The astute reader will have noticed that my structure above means that the Internet's existence is NECESSARY if we've assumed my blog post is a brute fact. So here is a problem for me - I don't understand how Randal can simply assert in his TBS that God's existence is NECESSARY without telling me what it is NECESSARY in relation to. And suppose he states that it's necessary in relation to the Universe, well, now I can accept the relationship in Randal's supposed TBS, while not accepting that it describes an actual state of affairs.
There are ways of getting universes without Gods, so while he may very well believe that God's existence is "necessary" (in relation to this universe), this doesn't pose even a slight challenge to me or Sean Carroll or anyone for that matter. All it tells me is what is going on in Randal's head, and while Randal's head is maybe not the worst example of the genre, this doesn't exactly bring a lot to the party in helping me address the question of whether God actually exists or not.
So let's get back to my mountain bike. Randal thinks that he has served me with a reductio ad absurdum, but I don't think this works. Yes, I can assert my mountain bike exists, AND I can accept that its existence is CONTINGENT on a number of things. Those things are NECESSARY for its existence, which is also a BRUTE FACT, and if it wasn't such a long ride from Ireland to Canada, I could pitch up at Rauser Cathedral and nail it to the door.
But I can't nail God to the door of Randal's cathedral. God is not a BRUTE FACT - God needs arguments to support his existence, and Randal's simple assertion of NECESSARY existence doesn't get us there. It looks like "defining God into existence". But, if we follow the logic above, Randal is actually making a much much weaker claim.
What then Randal's "theism simpliciter" in this sense? It's just a belief - a belief that God stands in a NECESSARY relationship to a CONTINGENT universe that we all accept exists as a BRUTE FACT. Maybe this has helped clear the air - Randal is not saying that God must exist - just stating his belief as to the nature of God's existence in relation to the here-and-now. Note that NECESSARY doesn't even have to be ABSOLUTE - after all, the NECESSARY internet is itself a CONTINGENT thing. Maybe the NECESSARY God is CONTINGENT on an even deeper metaphysical reality...
Maybe we've been arguing over words. Maybe I've been guilty of assuming that Randal is making a much bigger claim than the relatively modest one that he really makes. The bottom line is that even if God's existence stands in a NECESSARY relationship to the CONTINGENT existence of our universe in the Theistic belief structure, this doesn't mean that God is "necessary" (colloquially) to explain the universe - God still might not exist at all, *even if* theists believe that he is NECESSARY.
So, of course, I can therefore accept the above theistic belief statement represents Randal's position, and still maintain that a/ that relationship has not been demonstrated, and b/ I still don't think God actually exists in reality.
So now what?
[Written with a couple of wines on board, 30/10/2017. Edited slightly; 31/10/2017]