Posted 30 November 2012 - 05:51 PM
@Gilbo : Yeah I did do that change, because "know" is such a ridiculous word - it technically means being absolutely certain that something is true, but not only is that impossible it's not even how we use the word in everyday life. We say "I know I left my keys in the car" and turn out to be wrong all the time, and we can accept the evidence that we were wrong - which we wouldn't if we really were absolutely certain and accepted no possibility of being wrong at all.
I refuse to give "know" up to the solipsists because in practice it means "confident enough for all purposes" and that's a fine use for it. But in the context of theism/atheism debates it always leads to stupid semantic arguments and mind-reading so I tend to avoid it in those specific cases.
@Tirian : I said I'd prefer to talk about it in the miscellaneous section but I'm too lazy to start a new thread there, and I appreciate your graciousness, so...
Note I'm talking about why I believe what I believe, I'm not expecting this to convince anyone. If there were a clinching scientific argument against God's existence that could convince everyone this forum wouldn't exist.
Your question is a difficult one to answer because there are many concepts tied to "God" and I don't disbelieve them all for the same reasons or to the same extent, but the basics is really that I think every complex thing is made up of simpler things, and everything has a mechanism. I can't really conceive of this not being the case. There must be something down at the bottom so simple that it doesn't have a mechanism it just is, and physics hasn't gotten there yet but as far as I can tell they're getting pretty close; either way at our scales it might as well be sub-components all the way down.
Now when I think about a God, for one thing I don't know how an interventionist God would work. For example, making a woman pregnant. That sounds fine said like that, but we know women don't just "become pregnant" - there is a mechanism involved, an ovum and a spermatozoon meet and fertilize, the resulting egg implants and so on. What is it God actually does in that mechanism ? Maybe he makes a spermatozoon appear in the womb, or a fertilized egg, or makes a sperm nucleus appear inside the ovum... okay. But we also know something about how molecules and atoms work, and they don't appear out of thin air - how does God make them appear ? Actually that's wrong, they do appear out of thin air, but that again is a specific mechanism that has specific effects - and we know the probability of even a whole nucleus being spontaneously generated from quantum foam is vanishingly unlikely, so much it wouldn't happen in trillions of years - maybe God manipulated the probabilities ? And how did he do that ?
Basically God as a concept is effects-driven, not mechanism-driven. To illustrate the difference, compare a magic carpet to real flying objects. The magic carpet is defined by what it does, which is fly, and it does that perfectly, with maybe one or two plot-convenient restrictions. It will fly anywhere, anyhow, at any speed, exactly how you need it to fly. Can it fly faster than the speed of light ? Can it fly in space ? Can it fly with a hole in it, and how big a hole ? If you ask those questions you're getting into nitpicky science-fiction territory* and you're revealing the dirty little secret that "flying" is actually a complicated function. Now consider our real-life flying devices. None of them "just fly"; they all fly for a reason, they have a mechanism that causes them to fly, and that mechanism causes them to fly in certain ways. Helicopters, airplanes, gliders and rockets all fly very differently because they have different mechanisms. On the one hand with them we can easily answer all of the questions that were inane nitpicking for the magic carpet, because we know why they fly means we also know under what conditions they can or cannot fly. On the other hand it also makes them less powerful in many ways than the magic carpet - they need fuel, they aren't infinitely manoeuvrable, they don't work everywhere, they need to be certain shapes and sizes...
When people talk about God they talk about him as something purely effects-driven. God does this, God does that. How does God do those things ? He just does. What are his limitations ? None, except insofar as opinions differ. Where does God come from ? Nowhere by definition. What is God made of ? I'm not sure that's even a meaningful question. What are God's characteristics ? Here's a list - and they're all extremely high-order, deceptively-simple-but-actually-incredibly-complex characteristics, and here's a list of theological essays explaining how the apparent contradictions between them can be resolved.
Same thing with disembodied minds - how does that mind see ? How does that mind hear ? Does that mind perceive a difference between itself and the world around it ? (that's a perception that can be turned on and off in actual brains). Does it dream ? Does it have a subconscious ? Does it have separable functions ? (embodied minds do) Everything we know of that processes information has an information-processing system - how do you even theoretically process information without one ?
This kind of description that's focused on effects and complex functions while ignoring mechanisms is very characteristic of concepts humans invent, and extremely different from everything humans have discovered about the world. Of course I could always posit there is a mechanism to all those things, we just don't know it. I can even imagine such mechanisms - like, we could be like the Game of Life and God is the programmer and can make a glider appear where he wants with a few clicks... but at that point I'm assuming things I know nothing of, with huge implications on the nature of the Universe, to explain the existence of something I don't know exists in the first place.
So that would be a basic reason I don't believe in the supernatural, God included. The direct reason I don't believe God exists is the lack of convincing evidence (and I know many people do see evidence for the existence of God or the supernatural, I just haven't found it convincing) as well various contradictions or incoherencies that many concepts of God have, but this stuff is the reason I believe God doesn't exist. It's just inconsistent with the world as I see it.
*Speaking in schematic terms of course - in practice plenty of science-fiction treats its technology like magic and plenty of fantasy treats its magic like a science, and the author always explains thing only up to a certain level of detail. David Eddings still summarized the dichotomy well though - paraphrasing : "A science-fiction author will spend ten pages explaining how a watch works, a fantasy author will tell you what time it is and get on with the story".