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At some point, one does get down to first principles. Remember Newton's answer to "Why gravity"? It was "I make no hypothesis." If you ask "why" enough times, you eventually run out of answers. The modern explanation of "Why gravity?" is curved space-time, but "why curved space-time" is as good a question as "why gravity." At some point, you run out of justifications, and the only answer you can give becomes "Here is a model that makes accurate predictions."
(Does that make any sense?)
The point isn't to give a reason for everything. The point is to be able to make a model. It's not about "Why do things fall down?" "Gravity.", but "Why do things fall down?" "They have a force exerted on them by every object proportional to the product of their masses and inversely proportional to the square of their distance.". The second one actually lets you make predictions. General Relativity (the exact formulae, not just the general idea of curved spacetime) makes the model a little more accurate. It's not an answer to "Why gravity?" It's just a slightly better answer to the original question.
It does, because you are asking a different 'why' than scientists do; the scientist's question is 'why do I need to postulate this?' And when he/she asks 'why does this phenomenon happen?' he/she is asking 'What model can I use to explain this phenomenon?'
So, the question 'why gravity?' can be answered in the first way, saying that it models falling and revolving objects rather well, or in the second way in which case the answer is, as you say, curved spacetime. But the second question, it can only be answered in the first way, as of now; I'm tempted to say that those concepts which we can only answer in the first way are postulates, but I'm sure non-trivial brainstorming (which I don't feel like doing right now) will show that to be bullshit.
Edit: I think the why you speak of is a weirder version of the second, kinda influenced by words like 'fundamental.'
I have yet to read most of your post-2004 writings (making a living always seems to interfere), but I am guessing that your personal Mysterious Phenomenon was consciousness.
Anon, I started posting more often after Robin specifically asked me if I could do so. Do I get to know what, in your view, I'm doing wrong (or what Robin Hanson is doing right)?
Eliezer, you offer a lot of value and shouldn't post less (in other words, I disagree with anon). Personally I wish you'd communicate a little more directly though. This is probably one of your most egregious, melodramatically obtuse posts.
Perhaps this explains Hofstadter's puzzled reply to the Singularity, as for example at his 2006 Singularity Summit lecture. Although his thinking into the meaning of thought are surely insightful, it seems tinged at the end with a sense of that intelligence and the Singularity are Mysterious Phenomenon in the sense described above.
(However, it can sometimes hard to distinguish whether a speakeris saying "X is a Mysterious Phenomenon (in the sense above)," "X is something that I don't understand for now," and "I understand X, and so am filled with a sense of wonder.")
Or perhaps he wanted to leave his audience with a certain effect, like wonder, hope, and dreaminess? That's how I see the future sometimes, when I have no idea what tech will boom and bust.
Once I tried to temporarily 'forget' everything I knew about Newtonian mechanics etc. and see if I could just derive Newton's laws of motion just by observing things.
I realized that it was very, very, very hard. Aristotle's laws of motion make perfect sense - if you don't know Newtonian mechanics. Something as simple as 'objects in motion tend to stay in motion unless acted on by some external force' has very little bearing to intuitive reality. Even the concept of a 'force' is highly abstract and nontrivial if you think about it. This is perhaps even apparent in the language people use to describe force, even today. It is common to hear phrases like 'with the force of a thousand suns' or 'this motor has more force than that one'. People often confuse force with work and/or power (and don't get me started on how often power and work are confused). The fact that Newton and others were able to separate these things into their components and actually quantify them still amazes me. Energy/work is force times distance. Power is work over time. You can push against a solid wall with a lot of force but you are doing no work.
It's not that these concepts would have been mysterious. It's that people simply wouldn't have thought about them, at least not in a fundamental way.
Once upon a time, in my wild and reckless youth, when I knew not the Way of Bayes, I gave a Mysterious Answer to a mysterious-seeming question. Many failures occurred in sequence, but one mistake stands out as most critical: My younger self did not realize that solving a mystery should make it feel less confusing. I was trying to explain a Mysterious Phenomenon—which to me meant providing a cause for it, fitting it into an integrated model of reality. Why should this make the phenomenon less Mysterious, when that is its nature? I was trying to explain the Mysterious Phenomenon, not render it (by some impossible alchemy) into a mundane phenomenon, a phenomenon that wouldn't even call out for an unusual explanation in the first place.
As a Traditional Rationalist, I knew the historical tales of astrologers and astronomy, of alchemists and chemistry, of vitalists and biology. But the Mysterious Phenomenon was not like this. It was something new, something stranger, something more difficult, something that ordinary science had failed to explain for centuries—
- as if stars and matter and life had not been mysteries for hundreds of years and thousands of years, from the dawn of human thought right up until science finally solved them—
We learn about astronomy and chemistry and biology in school, and it seems to us that these matters have always been the proper realm of science, that they have never been mysterious. When science dares to challenge a new Great Puzzle, the children of that generation are skeptical, for they have never seen science explain something that feels mysterious to them. Science is only good for explaining scientific subjects, like stars and matter and life.
I thought the lesson of history was that astrologers and alchemists and vitalists had an innate character flaw, a tendency toward mysterianism, which led them to come up with mysterious explanations for non-mysterious subjects. But surely, if a phenomenon really was very weird, a weird explanation might be in order?
It was only afterward, when I began to see the mundane structure inside the mystery, that I realized whose shoes I was standing in. Only then did I realize how reasonable vitalism had seemed at the time, how surprising and embarrassing had been the universe's reply of, "Life is mundane, and does not need a weird explanation."
We read history but we don't live it, we don't experience it. If only I had personally postulated astrological mysteries and then discovered Newtonian mechanics, postulated alchemical mysteries and then discovered chemistry, postulated vitalistic mysteries and then discovered biology. I would have thought of my Mysterious Answer and said to myself: No way am I falling for that again.