Yet another productive conversation. It's always nice when these things don't devolve into shit-flinging (pretty much all the Cult of Gnu knows how to do), and discussing things with an actual deist is rare.
The discussion mostly centered around the division of faith and reason. It was granted that natural knowledge of God is possible, but argued by Walter that to make that next step - accepting revelation - is something other than reason. 'Faith, rather than reason'. Nothing too new on that front.
I defended two main claims in the discussion. First, it's entirely acceptable for a person to be agnostic about claims that they are unwilling and/or incapable of verifying for themselves. I think that position sounds reflexively reasonable to most people - except if it's consistently applied, it means it's acceptable to be agnostic about large swaths of scientific claims. Is relativity theory true? Most people would probably say 'yes', and most of those people probably haven't the foggiest idea of how they'd even begin to verify this for themselves - and no, getting a quote from a seemingly super-smart scientist doesn't help, or even finding a poll of scientists in the relevant field answering this question, doesn't help. That gets us as far as testimony, often second or third hand testimony, about facts and details that most of us are simply out of our league when it comes to investigating.
Note that I'm not saying that it's mandatory to be skeptical about these claims: I simply think it's a live, reasonable option. As I said in the thread, I don't think the usual moves here work. 'The smart scientists say..!' Great. How do I know they're really good at physics - the topic I know nothing about - again? Yet more second- and third-hand testimony? 'All scientists say'? First, this is often an asspull claim, and asking for the data to back it up is enough to shut down the conversation. But even with it - even with direct, widespread testimony - I'm still stuck in the position of trusting a bunch of people who I don't know about a field I am unfamiliar with, trusting their expertise which I am very incapable of gauging, about a topic I barely know how to begin investigating even if I wanted to. Saying it's mandatory that I believe the answers to difficult scientific questions strikes me as bizarre, and I think says a lot less about the desire to be reasonable than the desire to fit in with a certain subculture. Again, it's not that I'm arguing we SHOULD all be agnostic - I'm just going to hold up agnosticism, in that situation, as a live option.
On the flipside? I also believe it's reasonable to accept revelation provisionally based on one's own investigations into the relevant data. Again, in this conversation I didn't argue that one MUST accept revelation - I just held this conclusion, after such an investigation, to be in principle possible to arrive at. The key here is that this isn't about a special brand of religious faith - instead, from the perspective I argued for (and particular for the deist), it's just a surprisingly banal brand of reasoning that most people are otherwise happy to employ in their day to day lives, not only about scientific claims but historical claims as well. The Deist already accepts that God exists. Alleged testimony from God can be researched, examined, investigated. Proved definitely? Not empirically, no - but we can't prove very much at all empirically. We can do a reasonable job of weeding out charlatans, we can see if the claims square with the knowledge we arrive at via philosophy or metaphysics or even intuition, and we can provisionally accept the revelatory claims. Granted, this isn't necessarily perfect. But so what?
I think, after a pretty long discussion (sometimes animated too), my arguments stood up. The deist already accepts God's existence, and I think modest deism is vastly easier to defend than positive atheism. The idea that God would communicate with man is certainly not ruled out (some deists seem to actually think otherwise, and in the process load up deism with a dogma that is very difficult to defend), so a claim that a man communicated with God is not ruled out of court immediately. From there on, it's a pretty run of the mill display of reasoning to accept revelatory ('God-given') claims in principle. No appeals to mystical experience needed, though of course those aren't ruled out. No appeals to an unfamiliar or necessarily special form of faith. It may be more dispassionate than people are used to, but there's nothing obviously wrong with the approach, especially if deism is granted at the outset.
This actually puts me in a different corner than the philosophers I most admire, like Ed Feser or the ID gang or otherwise. While I love and accept various metaphysical arguments, I think getting to a bare and basic theism is far easier than most people (even most theists!) are willing to admit - and that the move from a bare deism/theism to religious belief is pretty small, all through pretty banal, common sense reasoning. On the flipside, I find it funny that people - including a lot of people who would normally claim to adhere to the claim of "It is wrong, always and everywhere, to believe something on insufficient evidence" (putting aside its other failings for a moment), will piss themselves when you go ahead and admit you won't believe some things you neither personally have nor understand the evidence for. I think van Inwagen said that Clifford's Principle is selectively deployed - it's brought out against religion, but almost never for (say) political beliefs. I think he didn't go far enough with his observation.