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gwern comments on My Wild and Reckless Youth - Less Wrong
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Problem: "retrospective predictions" is undefined here. Search does not locate this term anywhere on the LessWrong website, the LessWrong wiki or on Wikipedia, but it seems to be the crux of this piece that we have to make retrospective predictions. Also, it's not clear what you mean by it because it sounds oxymoronic - you can't predict something that already happened. My best guess about what you mean by "retrospective predictions" is: Say someone has a theory that humans are hairless because they evolved from aquatic monkeys. That person should "predict" that there's past evidence of aquatic monkeys existing at the right place/time/circumstance/whatever and then go do some research to find out.
Retrospective prediction is an expansion of http://en.wikipedia.org/wiki/retrodiction
Oh, thank you, Gwern! Ok, so retrodiction is more like this: There are facts that we currently know and phenomena that have already happened so you should consider whether your theory would have predicted them. It's not "did something related precede this" but "If we had known this theory before realizing certain facts or making certain observations, would the theory have predicted or explained these?"
Hmm for examples... if there were an all-knowing, all-powerful, all-loving God, what would I predict? If life on earth evolved, what would I predict?
What would God do? Make something awesome or lounge around feeling enlightened. I'm personifying here, and I know it... I have no idea what a God would do but I suspect that it would not be "Make a bunch of creatures knowing that a bunch of them will experience horrible suffering. Demand that they have faith but confuse them with a bunch of different religions to choose from. Create each of them knowing exactly how they'll reason and what they'll experience and what that combination will result in and demand certain beliefs that won't make sense to some of them."
Whereas with evolution, I'd predict that various life forms would evolve, some would succeed, some would not, life would be more like a chaotic experiment than a harmonious symphony, the smartest life forms would be dreadfully confused for quite some time before having it together...
And this sounds like earth.
I would expect most life to just end up as planets full of green goo (ie. like grey goo but natural). But I'd expect that in a tiny minority of cases things like Fisherian Runaway, complex signalling and just plain luck happen to throw some individual toward the 'general intelligence' path (and a bunch of other deal breaking to not happen on the way). I'd expect any intelligent agents to observe that they are on a planet, in a galaxy in an Everett Branch where life had evolved much like you said.
Hmm. I notice that I was not as specific as you are. I didn't say anything about what "most" life forms would be like or whether there would be lots of smart life forms. I haven't really done a thorough retrodiction on evolution, to tell the truth. But I am really liking this new imagination trick of "try to predict the past if the theory was true" (which is subtly different from my other tricks like "is there anything in the past that supports / refutes this?") and it's pleasant atheism-promoting effect on the remnants of my dead agnosticism phase. I'm glad I asked this question and that Gwern helped.
Thinking it out, I do not agree with your green goo hypothesis. I think that as long as there were mutations in the green goo's pattern (and stability in this pattern would be the exception not the rule due to the complexity of making a self-replicating, self-incarnating pattern, and due to environmental differences more complex and diverse than the green goo's pattern would be able to expect) and as long as there was always room for improvement (for something this complex that evolved randomly, perfection in the pattern would be the exception not the rule) it would have to change and mutate and new variations would inevitably emerge.
What would it take to have that kind of stability in life forms? Other than a perfectly stable planet? The life game is very, very complex.
I think, perhaps, a drastic reduction in the number of physical laws (when you have all kinds of neat toys to play with from electricity to friction, room for improvement is immense), as well as the number of substances available (otherwise the goo will only expand and encounter new things which promote adaptations), it MIGHT result in a simple life form becoming "perfect" for it's environment and then stabilizing it's genes as a way of optimizing perfection.
I think diversity and increasing improvement is more likely to result from evolution than perfect, stable green goo.
We may also have meant different things by "if life on earth evolved". I read it as "conditional on self replicating things we could call 'life' emerged on earth, how would I expect things to proceed" where it could also have meant "conditional on intelligent life like we know it having been evolved, how would I expect that process to have gone".
What I was intending to convey was not so much that one stable form of goo would remain permanently but rather that there is a significant component of the great filter in the stages between life emerging and general-intelligence evolving as well as the component before life emerges at all. I expect that most planets where life evolves at all to not evolve general intelligence or even other lifeforms as interesting as what we consider lesser animals. I expect it to get stuck in local minima rather frequently.
I disagree. The incentivising force for continued adaptation is changes in your environment (including your fellow other species). Static goo - or uniformly adapting goo - cannot be optimal for all of a planet at once, leaving room to be outcompeted by diversifying dark-green goo, which may eventually evolve into goo-man (I mean, hu-man):
A planet filled with homogeneous green goo would still be subject to offering advantages based on adaptation on two major axes:
1) Planets universally offer different conditions for habitats, pole temperature versus equatorial temperature, seismic activities on active planets, surface versus underground habitats. The green goo would eventually split off into various types, each best suited to the environment. There is no such thing as an "optimal green goo for every environment", optimal refers to a specific set of conditions. Some tasks are hard for single-celled organisms to fulfill, which is probably why the uniform green goo that life developed as on earth diversified while spreading, and that bacteria, while ubiquitous, still aren't considered the dominant life form.
2) As a hypothetical, even a planet transformed into a uniform green goo blob in space would be an environment in itself, allowing for niches for different forms of life (as long as there's still some entropy to waste i.e. a mechanism for mutation). For a crude comparison, think of lava as goo on a different time scale.
Lastly, if you allow certain variations in your green goo, you could well argue that earth as it is now is an amalgam of various sorts of green goo - us. Especially from the vantage point of our basic goo unit - the gene. See the goo now?
(To me, the curious thing isn't the eventual appearance of memetic-temetic based adaptability (intelligence), but of subjective experience to go with it. Good fiction novel on that: Peter Watts’ Blindsight.)
One might compare this to ecosystems of reproducing known-number iterated prisoner's dilemma robots - the analogous idea is that these ecosystems will usually end up as "tit for tat goo."
Tit for tat is reliable. Like algae in the sea of early earth, tit for tat can serve as a "background" for our ecosystem - cooperation is harvesting energy from the sun, defection is being a predator, but if everyone tries to be a predator everyone dies. So algae reproduces. But also like a sea full of algae, there are predatory / parasitic strategies that work really well once the plants are common, like defecting at the end, or eating plants. If a tit for tat robot has the first mutant baby that defects at the end, that baby will only play against tit for tat robots, so it will defect successfully and have more babies than usual, eventually leading to a whole new strain. The zooplankton of the ecosystem. But then if that becomes common, it may be worth it to produce a parasite to the parasite - defecting twice from the end. The bigger the possible rewards, the more layers of strategies will be viable. Tit for tat goo is unstable - plants quickly grow herbivores, and herbivores can sometimes grow predators.
And that's just iterated prisoner's dilemma. Add in more dimensions, multiple equilibria... things could get pretty complicated.
Yes, that's pretty much what retrodiction is. It's not as good as prediction since you can come up with theories over-fitted to exactly the past (a big problem with financial retrodiction: people routinely find some complex strategy or apparent arbitrage when running over the last 30 years of market data, which disappears the moment they tried to use it), but if predictions are unavailable, at least retrodiction keeps you concretely grounded.
I'm not sure I would use God as an example. Theists like Plantinga have done a good job showing that they can come up with a version of God + concepts like 'free will' which is logically consistent with any observation, so neither retrodiction nor prediction matters for their God.
I love it. Retrodiction is awesome.
I think I broke the free will God argument. The idea that evil is evidence that God gives us free will is contradicted by the existence of evil. What do you think?
In general, if someone thinks they've said something that is both new and valuable about the theodicy: they haven't.
Looking at your link, I have no idea what you're trying to say.
Well, I reworded my point as "The idea that evil is evidence that God gives us free will is contradicted by the existence of evil" but if you don't think it's going to be interesting, don't bother.