One of the best parts of writing a blog is being able to answer questions like this. Whenever I felt like I understood new and important, I wrote a post about it. This makes it easy to track what I learned.

I think the single most important thing I discovered this decade (due to a random comment in the SSC subreddit!) was the predictive coding theory of the brain. I started groping towards it (without knowing what I was looking for) in Mysticism And Pattern-Matching, reported the exact moment when I found it in It’s Bayes All The Way Up, and finally got a decent understanding of it after reading Surfing Uncertainty. At the same time, thanks to some other helpful tips from other rationalists, I discovered Behavior: The Control Of Perception, and with some help from Vaniver and a few other people was able to realize how these two overarching theories were basically the same. Discovering this area of research may be the best thing that happened to me the second half of this decade (sorry, everyone I dated, you were pretty good too).

Psychedelics are clearly interesting, and everyone else had already covered all the interesting pro-psychedelic arguments, so I wrote about some of my misgivings in my 2016 Why Were Early Psychedelicists So Weird?. The next step was trying to fit in an understanding of HPPD, which started with near-total bafflement. Predictive processing proved helpful here too, and my biggest update of the decade on psychedelics came with Friston and Carhart-Harris’ Relaxed Beliefs Under Psychedelics And The Anarchic Brain, which I tried to process further here. This didn’t directly improve my understanding of HPPD specifically, but just by talking about it a lot I got a subtler picture where lots of people have odd visual artifacts and psychedelics can cause slightly more (very rarely, significantly more) visual artifacts. I started the decade thinking that “psychedelic insight” was probably fake, and ended it believing that it is probably real, but I still don’t feel like I have a good sense of the potential risks.

In mental health, the field I am supposed to be an expert on, I spent a long time throwing out all kinds of random ideas and seeing what stuck – Boorsboom et al’s idea of Mental Disorders As Networks, The Synapse Hypothesis of depression, etc. Although I still think we can learn something from models like those, right now my best model is the one in Symptom, Condition, Cause, which kind of sidesteps some of those problems. Again, learning about predictive processing helped here, and by the end of the decade I was able to say actually useful things that explained some features of psychiatric conditions, like in Treat The Prodrome. Friston On Computational Mood might also be in this category, I’m still waiting for more evidence one way or the other.

I also spent a lot of time thinking about SSRIs in particular, especially Irving Kirsch (and others’) claim that they barely outperform placebo. I wrote up some preliminary results in SSRIs: Much More Than You Wanted To Know, but got increasingly concerned that this didn’t really address the crux of the issue, especially after Cipriani et al (covertly) confirmed Kirsch’s results (see Cipriani On Antidepressants). My thoughts evolved a little further with SSRIs: An Update and some of my Survey Results On SSRIs. But my most recent update actually hasn’t got written up yet – see the PANDA trial results for a preview of what will basically be “SSRIs work very well on some form of mental distress which is kind of, but not exactly, depression and anxiety”.

One place I just completely failed was in understanding the psychometrics of autism, schizophrenia, transgender, and how they all related to each other and to the normal spectrum of variation. I kind of started this program with Why Are Transgender People Immune To Optical Illusions? (still a good question!), fumbled around by first-sort-of-condemning and then sort-of-accepting the diametrical model of autism and schizophrenia, and then admitting I just didn’t know what was going on in this area and not talking about it much more. I still sometimes have thoughts like “Is borderline the opposite of autism?” or “Are schizoid people unusually charismatic, unusually uncharismatic, or somehow both?”, and I still have no idea how to even begin answering them. Autism And Intelligence: Much More Than You Wanted To Know at least helped address a very tangentially related question and is probably the closest thing to a high point this decade gave me here.

The Nurture Assumption shaped my 2000s views of genetics and development. Ten years later, I’m still trying to process it, and in particular to square the many behavioral genetics studies showing nonshared environment doesn’t matter with the many other studies suggesting it does (see eg The Dark Side Of Divorce and Shared Environment Proves Too Much). I think I started to get more of handle on attachment theory and cPTSD as both being different aspects of the same basic predictive processing concept of “a global prior on the world being safe” – see Mental Mountains and Evolutionary Psychopathology for two different ways of approaching this concept. This made me conclude that I might have been wrong about preschool (though see also Preschool: Much More Than You Wanted To Know). Honestly I am still confused about this. The one really exciting major good update I made about genetics this decade was understanding and fully internalizing the omnigenic model.

One of the big motivating questions I keep coming back to again and again is – what the heck is “willpower”? I started the decade so confused about this that I voluntarily bought and read Baumeister and Tierney’s book Willpower and expected it to be helpful. I spent the first few years gradually internalizing the lesson (which I learned in the 2000s) that Humans Are Not Automatically Strategic (see also The Blue-Minimizing Robot as a memorial to the exact second I figured this out), and that hyperbolic discounting is a thing. Since then, progress has been disappointing – the only two insights I can be even a little happy about are understanding perceptual control theory and Stephen Guyenet’s detailed account of how motivation works in lampreys. If I ever become a lamprey I am finally going to be totally content with how well I understand my motivational structure, and it’s going to feel great.

Speaking of Guyenet, if nothing else this last decade has taught us that Gary Taubes did not solve all of nutrition in 2004, that Atkins/paleo/keto are good for some people and bad for others, and that diet is still hard. See the various Guyenet vs. Taubes and Taubes vs. Guyenet posts, and my 2015 The Physics Diet on where I was at that point. So what is going on with diet? Compressing an entire decade’s worth of research into two words, the key phrase seems to be “set point” (which, credit to Taubes, he was one of the first people to popularize). See eg Anorexia And Metabolic Set Point and Del Giudice On The Self-Starvation Cycle. But what is the set point and how does it get dysregulated? See my book review of The Hungry Brain for the best answer to that I have now (not so good). This whole mess helped me get a better understanding of Contrarians, Crackpots, and Consensus, and eventually ended up with me Learning To Love Scientific Consensus.

In terms of x-risk: I started out this decade concerned about The Great Filter. After thinking about it more, I advised readers Don’t Fear The Filter. I think that advice was later proven right in Sandler, Drexler, and Ord’s paper on the Fermi Paradox, to the point where now people protest to me that nobody ever really believed it was a problem. AI has been the opposite – I feel like the decade began with people pooh-poohing it, my AI Researchers On AI Risk was part of a large-scale effort to turn the tide, and now it’s more widely accepted as an important concern. At the same time, the triumphs of deep learning has made things look a little different – see How Does Recent AI Progress Affect The Bostromian Paradigm? and Reframing Superintelligence – and I’ll be reviewing Human Compatible soon. I also got some really great insights on what “human-level intelligence” means from the good people at AI Impacts, which I wrote up as first Where The Falling Einstein Meets The Rising Mouse and later Neurons And Intelligence: A Bird-Brained Perspective (see also Cortical Neuron Number Matches Intuitive Perceptions Of Moral Value Across Animals and all the retractions and meta-retractions thereof). Overall I think I’ve updated a little (though not completely) towards non-singleton scenarios and not-super-fast takeoffs, which combined with the increased amount of effort being put into this area is cause for a little more optimism than I had in 2010. I know some smart people disagree with me on this.

In the 2000s, people debated Kurzweil’s thesis that scientific progress was speeding up superexponentially. By the mid-2010s, the debate shifted to whether progress was actually slowing down. In Promising The Moon, I wrote about my skepticism that technological progress is declining. A group of people including Patrick Collison and Tyler Cowen have since worked to strengthen the case that it is; in 2018 I wrote Is Science Slowing Down?, and late last year I conceded the point. Paul Christiano helped me synthesize the Kurzweillian and anti-Kurzweillian perspectives into 1960: The Year The Singularity Was Cancelled.

In 2017, I synthesized some thoughts that had been bouncing around about rising prices into Considerations On Cost Disease, still one of this blog’s most popular posts. I felt like early responses were pretty weak, although they brought up a few interesting points on veterinary medicine, cosmetic medicine, and other outliers that I still need to transform into a blog post; Alon Levy’s work on infrastructure in particular has also been great. The first would-be-general-answer that made me sit up and take notice was Alex Tabarrok’s book (link goes to my review) The Prices Are Too Damn High – but I explain there why I don’t think it can be the full answer. The most recent thing I learned (tragically underhighlighted in my wage stagnation post) is that a lot of apparent wage stagnation is due to cost disease – consumer services ballooning in cost means the consumer inflation index rises faster than the business inflation index, productivity gets measured by business inflation, wages get measured by consumer inflation, and so it looks like productivity is outpacing wages. This is still only half of the apparent decoupling, but it’s still a big deal.

The highlight/lowlight of the decade in social science was surely the replication crisis. My first inkling that something like this might exist was in December 2009, from the Less Wrong post Parapsychology: The Control Group For Science. There were a couple of years where people were trying to figure out how bad the damage was; of these, my 90% Of All Claims About Problems With Medical Studies Are Wrong was more optimistic, and my slightly later The Control Group Is Out Of Control was more pessimistic (I still stand by both). As the decade continued, I think we got better about realizing that many to most older studies were wrong, in a way that didn’t make us feel like total Cartesian skeptics or like we were going to have to throw out evolution or aspirin or any of the things on really sound footing. After that it just became fun: my “acceptance” stage of grief produced some gems like 5-HTTLPR: A Pointed Review.

On SSC, I particularly examined some of the replication issues of growth mindset. I started in 2015 by pointing out that the studies seemed literally unbelievable, but so far nobody had tried attacking them. I claim to have been way ahead of the curve on this one – if you don’t believe me, just read the kind of pushback I got. But by 2017, that situation had changed – Buzzfeed posted an article that called the field into question, but still without clear negative evidence. Finally, over the past few years, the negative studies have come pouring in, accented by supposedly “positive” studies by Dweck & co showing effect sizes only a tiny fraction of what they had originally claimed. The latest research (can’t find it right now) is that praising students for effort rather than for ability has no effect on how hard-working or successful they are, debunking the original headline result that got most people interested in the field and nicely closing the circle.

In 2010 I worked with a medical school professor who studied the placebo effect and realized I didn’t understand it at all. Over the past few years I gradually became more convinced of the heterodox position of Gøtzsche and Hróbjartsson, who believe placebo effect doesn’t apply to anything except pain and a few other purely mental phenomena (The Placebo Singers, Powerless Placebos). I’ve since become less convinced that’s true (just today I treated a patient who I’m pretty sure has psychosomatic vomiting from what he falsely believes was a medication side effect, and if belief can cause vomiting, surely it can also treat it). As with so many other things, it was predictive processing to the rescue – see section IV part 7 of my Surfing Uncertainty review. I now think I have a pretty good understanding of how placebos can treat both purely mental conditions and conditions heavily regulated by the nervous system, while still mostly sticking to Gøtzsche and Hróbjartsson’s findings.

I started this decade confused about how to understand ethics given all the paradoxes of utilitarianism. I’m still 90% as confused now as I was then, but I still feel like I’ve made some progress. A lot of my early thinking involved folk decision theory and contractualism – how would you act if you expected everyone else to act the same way? I explored the edges of this idea in You Kant Dismiss Universalizability and Invisible Nation. I’m not how much it helped my search for metaethical grounding, but it helped me get a more robust understanding of liberalism and clarify my views on some practical questions, eg Be Nice, At Least Until You Can Coordinate Meanness and The Dark Rule Utilitarian Argument For Science Piracy. In general I think this has given me a more cautious theory of decision-making that’s occasionally (and terrifyingly) set me against other more anti-Outside-View rationalists. I think the most important shift in my understanding of ethics this decade was the one I wrote up in Axiology, Morality, Law (formerly titled “Contra Askell On Moral Offsets”), which isn’t related to grounding utilitarianism at all but sure helps make the problem less urgent

Despite my better judgment, I waded into politics a lot this decade. I Can Tolerate Anything Except The Outgroup produced this blog’s first “big break”, but it admitted it didn’t really understand the factors underlying “tribe”. Since then Albion’s Seed helped provide another piece of the puzzle, and a better understanding of class provided another. I went a little further discussing why tribes have ideologies associated with them in The Ideology Is Not The Movement, how that is like/unlike religion in Is Everything A Religion?, and hammered it home unsubtle-ly in Gay Rites Are Civil Rites.

I wrote the Non-Libertarian FAQ sometime around 2012 and last updated it in 2017. Sometime, possibly between those dates, I read David Friedman’s A Positive Account Of Property Rights, definitely among the most important essays I’ve ever read, and got gold-pilled (is that a term? It should be a term). I’ve since been trying to sort this out with things like A Left-Libertarian Manifesto, and trying to move them up a level as Archipelago. James Scott’s Seeing Like A State and David Friedman’s Legal Systems Very Different From Ours were also big influences here. Like all platitudes, “government is a hallucination in the mind of the governed” is easy to understand on a shallow level but fiendlishly complicated on a deep level, but I feel like all of these sources have given me a deep understanding of exactly how it’s true.

The rightists (especially Moldbug) get the other half of the credit for helping me understand Archipelago, and also deserve kudos for teaching me about cultural evolution. My first attempts to engage with this topic were nervous and halting – see eg The Argument From Cultural Evolution. I got a much better feel for this after reading The Secret Of Our Success, and was able to bring this train of thought back to its right-wing roots Addendum To Enormous Nutshell: Competing Selectors. I’m grateful to the many rightists who argued about some of these points with me until they finally stuck.

I had more trouble engaging with leftists. I started with Does Class Warfare Have A Free-Rider Problem, and it took me way too long to figure out that this was one of the major questions sociology was asking, and that “an answer” would look less like “your game theory analogy is missing this one variable” and more like a whole library full of books on what the heck society was. Later the same engagement produced Conflict Vs. Mistake, which I am informed is still unfair and partially inaccurate, but which (take my word for it) is a heck of a lot better than the stuff I was thinking before I wrote it. More recently I’ve been trying to figure out a sympathetic account of activism (as opposed to the unsympathetic account that it’s virtue signaling and/or people who are really bad at figuring out what things are vs. aren’t effective). You can sketch the outline at Respectability Cascades and Social Censorship: The First Offender Model, and I’ll sketch the whole thing out sometime when I have enough emotional energy to deal with the kind of people who will have opinions on it.

I also had to grapple with the sudden rise of social justice ideology. I’m proud of my work on gender differences – both what I learned, how I wrote it up, and the few bits of original research I did (eg Sexual Harassment Levels By Field). My knowledge and claims started off kind of weak (Gender Differences Are Mostly Not Due To Offensive Attitudes), but I eventually feel like I got a really great evidence-based basically-airtight theory of what is going on with gender imbalances in different fields, which I posted most of in Contra Grant On Exaggerated Differences (I’m still thankful for the commenter who solved that one remaining paradox about math majors). And despite all the mobs and vitriol I think sound science has basically triumphed here – I was delighted to recently see as mainstream a blog as Marginal Revolution recently publish, without any caveats or double-talk, a post called Sex Differences In Personality Are Large And Important and get basically no pushback. I was a lot more pessimistic around 2017 or so and described some thoughts on how to make a strategic retreat in Kolmogorov Complicity And The Parable Of Lightning, which I still think is relevant in some areas. But I actually start the new decade really optimistic – I haven’t written up an explanation of why, but careful readers of New Atheism: The Godlessness That Failed may be able to figure it out, especially if they apply some of the same metrics I used there to track how social justice terms have been doing recently.

Upstream of politics, I think I got a better understanding of…game theory? Complex system dynamics? The most important post here was Meditations On Moloch; the sequel/expansion, whose thesis I have yet to write up in clear prose, is The Goddess Of Everything Else. Reading Inadequate Equilibria was also helpful here.

My understanding of “enlightenment” went from total mystical confusion to feeling like I have a pretty good idea what claims are being made, and mostly believing them. This line of thinking started with the Mastering The Core Teachings Of The Buddha review, and then was genuinely helped by Vinay Gupta’s contributions summed up in Gupta On Enlightenment, despite the disaster in the comments of that post. From there I progressed to reading The Mind Illuminated, and Is Enlightenment Compatible With Sex Scandals led me to discover The PNSE Paper, which as much as anything else helped ground my thinking here (the comments there were pretty good too).

And thanks to all of you who took the survey, I went from skepticism of birth order effects to saying Fight Me, Psychologists: Birth Order Effects Exist And Are Very Strong. This was bolstered by Eli Tyre and Bucky’s posts on Less Wrong about birth order in mathematicians and physicists respectively. Last year I expanded on that with a post on how birth order responded to age gaps (somewhat updated and modified here, thanks Bucky). Once this year’s survey results are in I expect to have a lot more data on exactly what causes birth order effects and maybe how to deal with them. If you haven’t taken the SSC survey this year, consider this your reminder to do it here.

Not many of these were total 180 degree flips in my position (though birth order, preschool, psychedelic insight, and the rate of scientific progress are close). And not many of them completely resolved a big question that had been bothering me before (though the Fermi Paradox paper, omnigenic model, and animal neuron work did). A few of them confirmed things I had only suspected before (growth mindset, gender imbalances, diet). Many of them feel like what MIRI calls “deconfusion”, turning a space full of unknown unknowns to one where you feel like you have a decent map of where the major problems are and what it would feel like to solve them. The enlightenment research seems to fit here – I went from “I have no idea how to even think about this question or whether it’s all fake” to “I don’t know exactly what’s going on here, but I know what needs to be explained, and it looks like the explanation will have a shape that fits nicely into the rest of my ontology.”

There’s an argument that I should learn less each decade, since I’ll be picking higher and higher fruit. My own knowledge can advance either because civilization advances and I hear about it, or because I absorb/integrate older knowledge that I hadn’t noticed before. Civilization advances at a decade per decade (or maybe less; see the Cowen & Southwood paper above), but each year it becomes harder and harder to find relevant older knowledge that I haven’t integrated yet. I plausibly only have five more decades to live, and I don’t think I’d be happy only advancing five times this amount over the rest of my life, let alone less than that.

But I notice I only started SSC about halfway through the decade, and that my progress picked up a lot after that. I don’t think it’s just recall bias from being able to track myself better. I think being able to put ideas out there and have you guys comment on them and link me to important resources I might have missed has been great for me. I only started taking full advantage of that around 2015; this decade I have a head start. And maybe I’ll discover other useful tools that will speed things up further.

Thanks for sticking around with this blog, and have a happy third decade of the twenty-first century.