A "meta-argument" against all future arguments for God's existence ?

[Belacqua]

This is very interesting. I've largely forgotten what Aristotle had to say about it but was it 'the form of living matter'? Ie under that conception there can never be matter without form, so soul is the special case that is the form of living matter? As opposed to an unnamed case of 'form' for any inanimate matter, including dead matter? If so I did wonder at the time while reading that how you'd get from that to a migrating soul, so interesting to see you explicitly state that Aristotle think didn't that was possible and Paul did.

No doubt I'm overstating the case if I say that this is THE Christian view of the soul. Naturally there are a lot of Christians and they don't agree on everything. Still, this is the classical theological view, and I think it makes sense to focus on this one if people are trying to define the word. I don't know why people just want to define it any way they want without at least checking what it has traditionally meant. 

As I understand hylomorphism (which is not that well), it applies to everything. The typical example is a bronze statue, where the material is bronze and the form is Zeus or whoever. Form only deserves the word "soul" when it's applied to a living body. There are plant-souls, animal-souls, and human-souls. But not rock souls. Rocks have form and matter but aren't alive, so we don't call their form a soul. 

The form gets applied to a living thing just in the way you'd expect -- we get born, we grow up, etc. Aristotle didn't know about DNA but it makes sense to say that form is transmitted largely by DNA. Since it's not something that can separated from its matter, Aristotle didn't think you could just lift off the form and give it to new matter -- any more than you could take your bronze statue of Zeus and magically transform its form into wood. How, for Christians, the soul gets translated into a spirit-body is one of those things that natural theology can't explain -- it's faith. 

My dad as a Christian doesn't think the soul is consciousness per se either, though it's hard to pin down exactly what he does think, though I don't think it's the Aristotlian conception, or at least not attributed to him if it is that or something like that. He also distinguishes a spirit as something different from a soul, and equally essential to life, but to me they're both just different ways of adding nothing to the equation, seemingly largely borne out of the view of living matter being fundamentally different from non-living matter - when to me there's no fundamental difference, just ultimately chemistry and physics at play in either case - but where that sort of 'life force' idea is most clearly exemplified by Aristotle's concept of a soul. I guess all those ideas stemmed from that concept, but I didn't know/infer that until I started reading Aristotle.

None of the Christians I know worry about theology at all. It's about behavior and group identity, being moral, etc. So I feel a little rude trying to pin them down on a definition of the soul. I suspect your dad is in the majority here, and I can respect that. 

He's correct, I think, to distinguish spirit, soul, consciousness, and other things, as different. We fuzzy up our thinking if we start to say they're just all the same thing. Why use two different words if soul and consciousness are the same thing?

Don't get me wrong, I think there is a nice simplicity about Aristotle's view of a soul, a useful special-case designation of the same matter/form distinction he makes for everything else... it just fits nicely within that existing system of thought without really changing anything... and to the extent that I'm willing to entertain Aristotle's perspective on the world, ie for the sake of argument, then I'm willing to accept that rather mundane concept of a soul, but that's still a far cry I think from the migrating soul that you say Paul envisaged.

I see Aristotle's definition as a non-supernatural idea that we should be able to agree on. Even if it's not that useful to how we think anymore, it's not a way-out kind of concept. Even mundane, as you say.

You're right, though, that to get from Aristotle to a full Christian view, where the soul is translatable and immortal, requires a bunch of additional belief. But what's at issue then is not what the soul is (it's still just the form) but what it's capable of, or what God does with it. That's certainly far from proven. 

(I joke that the form/matter distinction is most useful these days as a formula for making modern art. Choose the least appropriate material for a certain form -- say, a hacksaw made of glass or a bed made of ground beef -- and you'll be guaranteed a spot in your local art exhibition.)