[HN Gopher] Against Bayesianism - David Deutsch
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Against Bayesianism - David Deutsch
Author : jger15
Score : 55 points
Date : 2022-04-25 01:07 UTC (1 days ago)
(HTM) web link (josephnoelwalker.com)
(TXT) w3m dump (josephnoelwalker.com)
| JoshCole wrote:
| He doesn't actually argue against the Bayesian view of
| statistics:
|
| > The word 'Bayesianism' is used for a variety of things, a whole
| spectrum of things at one end of which I have no quarrel with
| whatsoever and at the other end of which I think is just plain
| inductivism. So at the good end, Bayesianism is just a word for
| using conditional probabilities correctly. So if you find that
| your milkman was born in the same small village as you, and you
| are wondering what kind of a coincidence that is, and so on,
| you've got to look at the conditional probabilities, rather than
| the absolute probabilities. So there isn't just one chance in so
| many million, but there's a smaller chance.
|
| His problem seems to be the extension of it to epistemology:
|
| > At the other end of the spectrum, a thing which is called
| Bayesianism is what I prefer to call 'Bayesian epistemology',
| because it's the epistemology that's wrong, not Bayes' theorem.
| Bayes' theorem is true enough. But Bayesian epistemology is just
| the name of a mistake. It's a species of inductivism and
| currently the most popular species. But the idea of Bayesian
| epistemology is that, first of all, it completely swallows the
| justified true belief theory of knowledge.
|
| His problem with inductivism is that when you follow it you don't
| try to make theories more believable by getting rid of ones that
| don't fit, but by confirming instances in which your theory does
| fit:
|
| > It's inductivism with a particular measure of how strongly you
| believe a theory and with a particular kind of framework for how
| you justify theories: you justify theories by finding confirming
| instances. So that is a mistake because if theories had
| probabilities - which they don't - then the probability of a
| theory ('probability' or 'credence', in this philosophy they're
| identical, they're synonymous)... if you find a confirming
| instance, the reason your credence goes up is because some of the
| theories that you that were previously consistent with the
| evidence are now ruled out.
|
| > And so there's a deductive part of the theory whose credence
| goes up. But the instances never imply the theory. So you want to
| ask: "The part of the theory that's not implied logically by the
| evidence - why does our credence for that go up?" Well,
| unfortunately it goes down. And that's the thing that Popper and
| Miller proved in the 1980s. A colleague and I have been trying to
| write a paper about this for several years to explain why this is
| so in more understandable terms.
|
| He cites this paper as an example of a proof, but claims it isn't
| very approachable (which is why he is working on one with more
| understandable terms).
|
| https://sci-hub.3800808.com/10.1038/302687a0
| SubiculumCode wrote:
| I don't usually make this kind of comment, but the comment to
| which I am responding should be occupying the top spot on this
| forum, not the trash flamewar comment that currently occupies
| the top spot. If your moderation system can't differentiate
| actual expertise from flamewar trolling, then is it fair to say
| that the moderation system is not working?
|
| edit: now its working :)
| andybak wrote:
| :-)
|
| There's a reason HN asks people not to make meta-comments on
| voting patterns etc. They are usually out of date by the time
| most people see them.
| pmoriarty wrote:
| The HN Guidelines[1] say:
|
| _" Please don't comment about the voting on comments. It
| never does any good, and it makes boring reading."_
|
| [1] - https://news.ycombinator.com/newsguidelines.html
| qsort wrote:
| > His problem seems to be the extension of it to epistemology
|
| Isn't that a bit of a strawman? Bayesian epistemology as stated
| would require someone to believe something like "drawing
| without replacement from this urn, I got 100 white balls and 1
| black ball, therefore there is a nonzero probability that this
| urn contains only white balls", which is not a belief I can
| imagine anybody to seriously hold.
| pmoriarty wrote:
| See _" The gambler's fallacy is not a fallacy"_[1] (which was
| recently discussed[2] on HN).
|
| [1] - https://www.kevindorst.com/stranger_apologies/the-
| gamblers-f...
|
| [2] - https://news.ycombinator.com/item?id=30973324
| rictic wrote:
| What's surprising about that belief?
| MatteoFrigo wrote:
| Here is my understanding of what Deutsch and the paper by
| Popper/Miller are trying to say.
|
| There are three concepts involved: an evidence "e", for
| example "I extracted 1 black ball"; a hypothesis "h", for
| example "the urn does not contain only white balls"; a theory
| "h <- e" that, by means of logic or otherwise, deduces the
| hypothesis from the evidence. Your (qsort) theory is that if
| you see a black ball then the hypothesis is correct.
|
| Everybody, including you, me, and Deutsch, agree that if the
| probability of the evidence goes up, then the probability of
| the hypothesis goes up as well.
|
| What Deutsch and Popper/Miller are also saying, however, is
| that if the probability of the evidence goes up then the
| probability of the _theory_ goes _down_ (proof in the paper).
|
| I need to study the paper more carefully, because I am not
| 100% sure that it is strictly correct (there are many factors
| that would transform a < into <= if they were 1, and I
| suspect that some are), but I believe the weaker statement
| that if the evidence goes up the probability of the theory
| does not go up at all.
|
| In any case, this conclusion is consistent with what all
| scientists have believed forever: the only way to increase
| confidence in a theory is to try to break it. Or at least
| they believed this until fact checkers and censorship came
| along and threw the baby away with the bathwater.
| mgh2 wrote:
| pmoriarty wrote:
| He only started talking about Bayesianism about 29 minutes in
| to the podcast.
|
| Don't blame him for that... the interviewer asked him all sorts
| of tangential questions before finally asking him about
| Bayesianism directly.
|
| But even some of the earlier things he talks about
| (particularly Popper's objections to inductivism) are actually
| relevant to his critique of "Bayesian epistemology", which he
| claims is "a species of inductivism" (which, to his mind,
| Popper demolished).
| mnl wrote:
| So that's the best appraisal you can give of David Deutsch:
| "Just an old man seeking attention"?
|
| Well, leaving aside the usual embarrassment I feel when it
| comes to the impromptu nonsense a fair share of HN commentators
| think it's worthwhile to contribute here when there's a piece
| of news involving physics or physicists, that's an ageist take
| without any content whatsoever.
|
| There's more old people who know what they're talking about
| than young people. That's just the obvious consequence of
| having been around reading and thinking about stuff more time.
| You'll notice it eventually because as the song goes, time
| waits for no one.
| mgh2 wrote:
| Fair enough, my initial comment was "just a man", reversed.
|
| Give it a try, perhaps you are more patient. Today's
| oversaturated information makes listeners harsh critics.
| mnl wrote:
| Yep, we're getting too impatient and that's not helpful
| when it comes to think deeply about what we've been taught.
| Yet that's the most important part of any job IMO. I'll
| check it out, maybe you're right and he's rambling. That
| would be surprising to me, which is the reason I replied to
| your post.
| throwanem wrote:
| I don't think he's rambling. He isn't sure what
| familiarity his audience will have with the intellectual
| underpinnings of his argument, so he recaps those before
| embarking on the argument proper, in order to make sure
| the audience can follow.
|
| Granted, he does tell a couple of anecdotes in the
| process, but maybe that's his style. I think it's fair to
| consider impatience implicated here - for what it's
| worth, when I find myself feeling that way about coverage
| of stuff I already know but not everyone is guaranteed
| to, I usually just skip ahead or scroll ahead, checking
| in here and there, until I hit something on point or that
| I _don 't_ already know. (Usually the second one!)
|
| Impatience is an emotion, and while we can't help much
| what we feel or how we feel it, we _can_ most of the time
| treat what we feel as _input_. Think of it, if you want,
| like a Datadog alert. How do we handle those? By
| investigating to understand the root cause and taking
| whatever action that requires in the context, if any. If
| we let them drive our behavior directly without taking
| the time for considered action, we easily risk causing
| more problems than we 're likely to solve.
|
| Granted, I don't entirely love this metaphor, which is no
| less flawed than any. Maybe too some dork on Twitter will
| use this as an example of the mechanistic techbro
| attitude endemic to the diseased discourse of Hacker News
| comments, or something; it does lend itself somewhat to
| such misrepresentation.
|
| But despite that lossiness I think it's not wholly
| without use, because it _does_ point at least vaguely
| toward a way in which we can manage and make valuable use
| of even the most unpleasant among our emotions, and one
| that 's served me well over the years since I stumbled
| upon the concept in some writing or other, I've long
| since forgotten where.
|
| (I don't think Deutsch was rambling, but _I_ certainly
| am, in an effort to distract myself from a quite
| unpleasant facial pain I can 't do anything meaningful
| about until Thursday. Please excuse me.)
| melony wrote:
| Deutsch is one of the fathers of quantum computing. It is
| like telling Claude Shannon to get off your lawn because he
| didn't directly invent 5G.
| andybak wrote:
| That's not the comment I was expecting to see at the top.
|
| I haven't read TFA yet but I popped in to say how much respect
| I've got for David Deutsch and what an influence he has been on
| my intellectual development.
| YeGoblynQueenne wrote:
| I read the transcript and he doesn't seem to be rambling any
| more than anyone else speaking off the top of their head,
| rather than writing a carefully edited essay.
|
| Also what mnl said. I hope their comment helps you see your
| comment in the context of how it would appear to people who
| read HN with a hostile attitude and look for reasons to reject
| it (not mnl obviously).
| oh_sigh wrote:
| I'm 25 seconds in and I couldn't agree more. When will he get
| to the point? It feels like an eternity.
| SubiculumCode wrote:
| /s for ya
| PheonixPharts wrote:
| This is an awful take, and I hope other readers ignore it, and
| give the podcast a listen/read.
|
| It's a long podcast, and if you skim the transcript you can see
| that the discussion doesn't start until much later.
|
| I'm a pretty strong Bayesian, and have heard more than my fair
| share of vague, hand wavy, and stubborn frequentist arguments
| against Bayesian statistics. When I see an "Against
| Bayesianism" rant, I'm already biased against it from seeing so
| many awful arguments thrown out there, mostly to troll
| Bayesians.
|
| This is absolutely _not_ one of those. This is a very
| thoughtful and clearly articulated discussion of the
| applications of, what Deutsch easily agrees, is a correct
| statistical methodology to larger epistemological questions.
|
| It is long, so I only had a chance to skim this but it is
| incredibly obvious that David Deutsch is not "seeking
| attention", but has very legitimate concerns with the mindless
| application of Bayesian reasoning to larger epistemological
| problems in science. I'll certainly be revisiting this later
| for a closer listen.
| Veedrac wrote:
| > This is a very thoughtful and clearly articulated
|
| Can you point to a part that you think fits that description?
| Because it read as complete nonsense to me.
| floxy wrote:
| >I'm already biased against it from seeing so many awful
| arguments thrown out there
|
| So you are telling me your priors are based on frequency of
| occurrence? ;-)
| [deleted]
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