If the universe (our experience, our lives, our physical reality) weren’t complex (unpredictable, undecidable) what would it be?
This is not rhetorical question.
It is not easy either.
Can you imagine an alternative?
It would be useful if we could so we can go look for evidence of the thing you imagine. Why would we do this? The growing research in “complexity” and “complex systems” make some assumptions based on irreducibility, computation equivalence and so forth that suggest less complex things are not capable of universal computation, and in some sense, the ability to evolve ever more interesting/complex things, like our universe.
Social Mode 
Well, I doubt you should limit your metaphysical questions at all but…
Complexity is subjective… not empirical or rational.
Fire was complex at one time…even magical so, with subjectivity firmly established it is clear that 100, 1000, or perhaps 1,000,000 years from now quantum mechanics and Ziggy Marley will seem simple and logical and even cute while the things those cyborgs are working on seem waaaaaay too complex.
But then again… fire is complex…
Actually we can find a course other than complexity. Isn’t that called boredom??!!
We in America live in a symbolic world for the most part… There are no life / death imminent issues. We have little hand-to-mouth existence and those that really do have it hand-to-mouth don’t live in the sphere of complexity that you appear to be referencing.
In the symbolic world when there is no life – death complexity we get to create complexity in order to escape from boredom or stimulus deprivation that seeps into our existence. Escape into complexity is one way we keep our senses sharp but it is also VERY reinforcing as are other methods of symbolically putting ourselves in harms way. The list is endless…we play violent professional sports, we drive 80 mph while on the phone, we climb mountains, we invest in stock markets, start wars that we later tire of, go to the moon, surf, ski and otherwise put ourselves in harms way to then find load up exhilaration and the reinforcement that comes from escape from those actions…. just to do them again.
Well, it is almost the 4th of July and I have to go get some fireworks to shoot off, some charcoal to ignite with gasoline and have a brew or two before I drive to the lake to go jet-skiing in the waves.
I leave the metaphysics alone usually due to the exact point you make. Most metaphysical questions arise due to lack of data that eventually will be found.
This question is yet unresolved, though I suspect it will be explained soon enough.
I don’t mean complexity and undecidable in the sense that one day we will have the technology to unravel it. There are simply phenomena that we will never be able to fully unravel – literal undecidable/unknowable problems. e.g. we cannot know how, when, if the universe will end until, well, it ends (if it ends!). There will be no way of knowing this. We would have to somehow “get in front of it” to be able to predict it (lack of prediction doesn’t imply no way of understanding). It’s the halting problem in some sense. There’s no way to know if a computer program will halt before it halts. if you don’t like that metaphor – there’s not enough time to collect and make sense of the data that would tell you if the universe if going to end before the universe ends.
There are “smaller” problems though that are complex enough to be out of our reach of total knowledge. I suspect behavior and derivatives of behavior (markets, organizations, politics) will remain mostly uncracked. and so on…
So my question really is… imagine if we could crack it all. Imagine we could know everything fully (which would imply the universe is simple enough for us to understand it all).
a) what would that be?
b) could something that simple produce something like “us”
c) would anything made up of that simple stuff ever need to understand all that simple stuff
my thoughts:
a) i think it would be a very static system that is nicely stable
b) no. and this is a weird thing. truly simple things cannot do interesting things like produce something like us. Most things we think are simple actually are not.
c) no. simple things would just keep going according to the plan.
I’ll hit MAson’s comment next….