8 ms·
Are our brains Bayesian? (2016)
- User23 8y agoDo our brains use a reasoning process invented by our brains?
- taneq 8y agoWell, when (and if, I guess) we do finally properly understand how our brains work, then we'll know (somewhat tautologically) that they do use a reasoning process discovered by our brains.
- double0jimb0 8y agoWho’s asking?
- seppin 8y agoIs god in the image of a man? Probably not.
- virgilp 8y agoYou're downvoted, but I think you were just pointing out the reverse causality in the parent post, right? I.e. even if our brains are Bayesian, it's not that "they use a process discovered by them", it's just that they managed to decode what is the process that they were already using. Which doesn't seem ridiculous at all.
- User23 8y agoIt's not even a matter of causality, it's just a category error. Are there cranial phenomena that are analogous to Bayesian statistics? I don't see why not. But that doesn't mean that is how the brain operates. It's a matter of membership not isomorphism.
- kristoff_it 8y agoCould our brains have come up with a way of describing a process that was already there before?
- zby 8y agoDiscovered not invented.
- User23 8y agoDoes it exist somewhere in a platonic realm of forms?
- jamesrcole 8y agoIf our brains are Bayesian, evolution is what invented it.
- User23 8y agoWhen I studied biology it was drilled into us that evolution doesn't have agency. Has that changed?
- stan_rogers 8y agoNot as such, no, but if a heritable trait increases the likelihood of survival to reproduction, there is little other than unnecessary pedantry in the way of saying in a lay forum that evolution "invented" it.
- jamesrcole 8y agoI don't mean "invented" in the sense of conscious design process with foresight or intentions. I just mean the way the blind evolutionary process creates any "design".
- coldtea 8y agoYou don't need to have "agency" to invent. LSD and sticky notes were invented by accident -- as were tons of other things. Sure, one could add several pedantic reservations here, if they wanted to be thick on purpose, but the meaning of the parent's statement is clear. This series of passive aggressive counter-questions seems to violate the principle of charity.
- mygo 8y agoInvented? How do you know it didn’t exist before?
- gregw2 8y agoAre our brains Bayesian? 1990s Internet debater #1: "The plural of anecdote is not data" 2010s Internet debater #2: "True, but it does make a good bayesian prior"
- deleted 8y ago[deleted]
- mlechha 8y agoWhenever this comes up, I think about the conjunction fallacy https://en.m.wikipedia.org/wiki/Conjunction_fallacy https://en.m.wikipedia.org/wiki/Conjunction_fallacy. The observation that human subjects seem to assign higher probability to joint events than a single event. Which is weird because the probability of two events at the same time (conjunction) is always less than or equal to the probability of a single event on its own. How does the Bayesian brain hypothesis deal with this fallacy? It seems to me that nothing based on classical probability can explain this fallacy. So either the observation that humans can assign higher probability to joint events is wrong or human decision making isn't exactly probabilistic (in the classical sense, can't rule out exotic probabilistic approaches). EDIT: As several folks have commented that the conjunction fallacy can be explained away by different arguments based on interpretation and semantic issues. Indeed, the original Linda problem was susceptible to these issues. However, since then several researchers have tried to study this effect more carefully and it seems to still persist. An example that I'm aware of is the following https://link.springer.com/article/10.3758/BF03195280 https://link.springer.com/article/10.3758/BF03195280 where the authors used unambiguous language and a betting paradigm, but still found the effect. Again, this is most likely not fool proof. Regardless, I do not think the fallacy can be trivially explained away as an effect of ambiguous language.
- Scea91 8y agoRegarding the Conjunction fallacy my theory is that many people who are not used to math problems implicitly modify the question based on the context. Instead of choosing from options: 1) Linda is A 2) Linda is A and B they might actually understand the first statement in the context of the second statement as: 1) Linda is A and not B
- bsza 8y agoFWIW, there was a similar experiment in the form of a dice game [1], and the phenomenon was still present. [1] https://www.lesswrong.com/posts/QAK43nNCTQQycAcYe/conjunction-fallacy https://www.lesswrong.com/posts/QAK43nNCTQQycAcYe/conjunctio...
- jonathanstrange 8y ago
- sunstone 8y agoYes of course it is. Experience allows you to make decisions without having a statistically valid sample all the time.
- gooseus 8y agoI'm currently reading The Book of Why by Judea Pearl and I think that he makes that claim that our brains are Bayesian and then some. Haven't finished yet, he gets into artificial intelligence in the next few chapters, but he seems to make the claim that our brains work by doing a number of computations involved in causal inference beyond just Bayesian inference, such as subconsciously constructing causal diagrams and using them for causal inference including asking questions about counterfactual scenarios. Would be interested to hear if anyone else who has read this book can help elaborate on this some.
- eli_gottlieb 8y agoJudea Pearl continues to insist on causal diagrams, but the rest of us have moved on to probabilistic programs ;-).
- throwaway487548 8y agoThis is actually an idiotic question. The molecular biology does not employ a concept of a number (or any concepts whatsoever in principle), since this requires an intelligent observer (to form the abstract notion of a number) which is not available at that level. The "concrete", real-world biological systems, including our brains, however employs frequencies and "weights", which corresponds to wideness of a pathway, which does not require any numbers or counting. Mother Nature Does Not Count (and it does not compute any probabilities, of course). Higher level intellect does. Math and logic are superimposed on the Universe and Nature. It is naive to assume that the Universe and Nature is based on math and logic, as ancient Greek views suppose. Yes, there is basis behind Modus Ponens - in a certain conditions having Hs and Os inevitably leads to H2Os because universe has its laws, and because it has its laws it produces certain regularities and certain patterns which could be matched and even generalized by an intelligent observer, but it is not the other way around.
- cannabis_sam 8y ago>Math and logic are superimposed on the Universe and Nature. It is naive to assume that the Universe and Nature is based on math and logic, as ancient Greek views suppose. I think it’s more naive to think that the question has been settled.. https://en.m.wikipedia.org/wiki/Mathematical_universe_hypothesis https://en.m.wikipedia.org/wiki/Mathematical_universe_hypoth...
- throwaway487548 8y agoIt depends on who is asking. If it is a "good" philosopher, who is in on the quest to unveil the nature and laws of what is, then it is settled. If, however, you are fond of joggling with abstractions and of studying of philosophers themselves and various philosophical systems (instead of what is) then, of course, you could put together yet another pile of abstractions and even systematically compare it with another pile of abstractions, and so on. Lots of people do. Universe is one (at least we and everything else is bound by this one single unfolding process we call Universe) while abstractions are infinite, and most of them are disconnected from what is - they generalize nothing but other disconnected abstractions.
- jedberg 8y agoI've been studying how the brain works since college, which is now 20+ years. One thing a professor said back then really sticks out -- "we always assume that the brain works the same way as the most advanced computing of the time". In the 50s we assumed the brain worked like a telephone switching system. In the 80s we assumed the brain worked like a bunch of transistors. In the 90s we finally switched it up, and developed computing paradigms based on human biology, and came up with applying neural nets to brain science. Then someone had the idea to create a Bayesian NN. Each iteration we get closer to explaining how the brain works, but showing that each iteration is closer to workable based on our knowledge of the biology of the brain. But we still have no idea how we get from brain biology to rational (and irrational) thought. I'd be excited if we solved this within my lifetime.
- TaupeRanger 8y agoI don't think it will be, unfortunately. I think it's important to distinguish between explaining "how the brain works" and "understanding the brain, the mind, and their relationship". There are hundreds of studies every year elucidating correlations between certain kinds of brain activity and certain states of conscious experience. There are also many valiant attempts at modeling various aspects of human cognition and brain function. Unfortunately, none of this research says anything at all about the nature of the actual feelings and experiences we have. People are taught in school that a sufficient response to the question "how do we hear things?" is to talk about sound waves, the shape of the outer ear, the tympanic membrane, malleus, incus, stapes, cochlea, etc. At some point you arrive at: "and then the brain processes the signal in the auditory cortex and stuff." We have become accustomed to this sort of answer, but it really doesn't even begin to answer the real (and interesting) question: why does all that processing result in the felt experience of hearing, rather than the nervous system just bubbling up and causing a behavior with no feelings? Why does it "feel" that way and not some other way? Is there a different kind of hearing that "feels" fundamentally different from our experience? My point is that, we are closer to explaining some functional aspects of the brain, but when it comes to explaining the nature and character of our qualitative experience, we are at the same place as the ancient Eastern philosophers - we've really gotten nowhere.
- wnoise 8y agoSee also the book _Surfing Uncertainty_ (https://www.amazon.com/Surfing-Uncertainty-Prediction-Action-Embodied/dp/0190217014/ https://www.amazon.com/Surfing-Uncertainty-Prediction-Action...) which convincingly details many brain subsystems as approximating Bayesian updates.
- analog31 8y agoMy understanding of Bayesian thinking is that we form new beliefs that are a function of our prior beliefs plus new evidence. That's my interpretation of the article. Another way of thinking is to form new beliefs that are a function of prior evidence plus new evidence, e.g., by setting all old beliefs aside and starting afresh with the complete body of available evidence. It's not clear to me that these two methods produce the same results, though I can't think of a counterexample. But to the extent that our brains probably remember both beliefs and evidence, we are not probably not fully Bayesian.