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Relatedly, David Deutsch's "Simple refutation of the ‘Bayesian’ philosophy of science" > By ‘Bayesian’ philosophy of science I mean the position that (1) the o

by dotsam 2y ago

Relatedly, David Deutsch's "Simple refutation of the ‘Bayesian’ philosophy of science" > By ‘Bayesian’ philosophy of science I mean the position that (1) the objective of science is, or should be, to increase our ‘credence’ for true theories, and that (2) the credences held by a rational thinker obey the probability calculus. However, if T is an explanatory theory (e.g. ‘the sun is powered by nuclear fusion’), then its negation ~T (‘the sun is not powered by nuclear fusion’) is not an explanation at all. Therefore, suppose (implausibly, for the sake of argument) that one could quantify ‘the property that science strives to maximise’. If T had an amount q of that, then ~T would have none at all, not 1-q as the probability calculus would require if q were a probability. > Also, the conjunction (T₁ & T₂) of two mutually inconsistent explanatory theories T₁ and T₂ (such as quantum theory and relativity) is provably false, and therefore has zero probability. Yet it embodies some understanding of the world and is definitely better than nothing. > Furthermore if we expect, with Popper, that all our best theories of fundamental physics are going to be superseded eventually, and we therefore believe their negations, it is still those false theories, not their true negations, that constitute all our deepest knowledge of physics. > What science really seeks to ‘maximise’ (or rather, create) is explanatory power. https://www.daviddeutsch.org.uk/2014/08/simple-refutation-of-the-bayesian-philosophy-of-science/ https://www.daviddeutsch.org.uk/2014/08/simple-refutation-of...

adrianN 2y ago
„The sun is not powered by fusion“ actually contains a little information as to the inner workings of the star, so I’m a bit confused by the argument.
- ThomPete 2y ago
  Not from a non-bayesian perspective. It's what Deutsch would call a "bad explanation" i.e. it's easy to vary and thus doesn't tell us about how the sun is powered.
  - kerkeslager 2y ago
    It's a bad explanation because the sun (probably) IS powered by nuclear fusion. Deutsch is confused by this situation because he doesn't have the scientific background to understand the usefulness of negations of hypotheses. Historically, for example, a lot of people believed the sun revolved around the earth. If we treat this as T, then ~T is "the sun does not revolve around the earth". ~T certainly lacks details, but to say it's a "bad explanation" is rather silly. Obviously it's an incomplete explanation, which is why Galileo presented a full explanation ("the earth revolves around the sun") rather than just saying, "the sun does not revolve around the earth". But in fact, "the sun does not revolve around the earth" was the part that was controversial because it was the bad explanation being presented by the church (who happened to be closer to philosophers than scientists). Basically, Deutsch is just making a straw man argument. In Deutsch's mind, the fact that "the sun does not revolve around the earth" is an incomplete theory of heliocentrism is somehow a refutation of all science, when in fact that's simply not the sort of hypothesis scientists even explore typically.
    - parodysbird 2y ago
      He's talking about Bayesian philosophy of science, not science, which ultimately does not rely on Bayesian epistemology.
      - kerkeslager 2y ago
        Agreed--in fact, science doesn't rely on philosophy at all. If the entire field of philosophy disappeared, science would go on functioning just fine. In fact, science has generally been hindered by philosophy--it's seemingly impossible to discuss scientific methodology without some wanker interjecting "well ackchyually nothing is knowable". Animals with nervous systems were learning from observation before humans invented enough language to epistemologize, and will continue to do so with or without philosophers. Bayesian epistemology is an attempt to model why science works--it relies on science, not the other way around.
        ThomPete 2y ago
        Science do in fact rely on philosophy that's how we got the scientific method.
kerkeslager 2y ago
Bullshit like this is exactly why I think scientists are better philosophers than philosophers are. The text you've quoted, is, frankly, not the writings of an intelligent person. The reason I'm being very blunt about this, is because bullshit like this is actively harmful. Science is fucking important. Science is what resulted in the technology you're using to read this. Science is, with non-negligible probability, the basis of medicine that prevented you from dying before the age of 5 to be able to read this. When philosophers posit that they can inspect the their own navels and find deep truths about the world, they are undermining one of the fundamental pillars of society that holds up so much of the positive changes humans have been able to make. We need to call this what it is--nonsense and misinformation--and stop amplifying its signal. > By ‘Bayesian’ philosophy of science I mean the position that (1) the objective of science is, or should be, to increase our ‘credence’ for true theories, and that (2) the credences held by a rational thinker obey the probability calculus. However, if T is an explanatory theory (e.g. ‘the sun is powered by nuclear fusion’), then its negation ~T (‘the sun is not powered by nuclear fusion’) is not an explanation at all. Therefore, suppose (implausibly, for the sake of argument) that one could quantify ‘the property that science strives to maximise’. If T had an amount q of that, then ~T would have none at all, not 1-q as the probability calculus would require if q were a probability. Of course "the sun is not powered by nuclear fusion" IS an explanation, it's just not an explanation of a phenomenon we observe, which is why most scientists don't believe "the sun is not powered by nuclear fusion". If we observed something about the sun that was not consistent with the hypothesis that it is powered by nuclear fusion, "the sun is not powered by nuclear fusion" would indeed be an explanation of what we were observing. This is all sidestepping the absurdity that Deutsch doesn't seem to understand that "none at all" has a mathematical representation, 0, meaning that if p = 1 - q = 0, then q = 1. This is not difficult math here, folks. > Also, the conjunction (T₁ & T₂) of two mutually inconsistent explanatory theories T₁ and T₂ (such as quantum theory and relativity) is provably false, and therefore has zero probability. Yet it embodies some understanding of the world and is definitely better than nothing. Uh sure, which is why nobody with a brain takes the conjunction of those two things. This isn't a criticism of Bayesian philosophy of science, it's a straw man argument. > Furthermore if we expect, with Popper, that all our best theories of fundamental physics are going to be superseded eventually, and we therefore believe their negations, it is still those false theories, not their true negations, that constitute all our deepest knowledge of physics. Deutsch apparently doesn't know what an approximation is, and instead thinks of correct/incorrect as a binary. Relevant https://hermiene.net/essays-trans/relativity_of_wrong.html https://hermiene.net/essays-trans/relativity_of_wrong.html
marcosdumay 2y ago
Any refutation that depends on the fundamental unknownability of the Universe rules trivially applies to every single philosophy of science. Science must work despite it, or you don't have science. And any other singularity you get from assuming the odds of a hypothesis is infinitely smaller than the odds of it being false is unrealistic. You shouldn't assume that.
hammock 2y ago
Love this. So clearly written. The truest thing we know is how much we don’t know
badRNG 2y ago
> we expect, with Popper, that all our best theories of fundamental physics are going to be superseded eventually This inductive case against scientific knowledge should only serve to decrease our second-order credence in the proposition that we have assigned the highest credence to the scientific hypotheses that most closely correspond with reality. It does nothing to change the fact that, conditional on evidence we currently have, we may very well have correctly proportioned credence.

by dotsam 2y ago

adrianN 2y ago

„The sun is not powered by fusion“ actually contains a little information as to the inner workings of the star, so I’m a bit confused by the argument.

ThomPete 2y ago
Not from a non-bayesian perspective. It's what Deutsch would call a "bad explanation" i.e. it's easy to vary and thus doesn't tell us about how the sun is powered.
- kerkeslager 2y ago
  It's a bad explanation because the sun (probably) IS powered by nuclear fusion. Deutsch is confused by this situation because he doesn't have the scientific background to understand the usefulness of negations of hypotheses. Historically, for example, a lot of people believed the sun revolved around the earth. If we treat this as T, then ~T is "the sun does not revolve around the earth". ~T certainly lacks details, but to say it's a "bad explanation" is rather silly. Obviously it's an incomplete explanation, which is why Galileo presented a full explanation ("the earth revolves around the sun") rather than just saying, "the sun does not revolve around the earth". But in fact, "the sun does not revolve around the earth" was the part that was controversial because it was the bad explanation being presented by the church (who happened to be closer to philosophers than scientists). Basically, Deutsch is just making a straw man argument. In Deutsch's mind, the fact that "the sun does not revolve around the earth" is an incomplete theory of heliocentrism is somehow a refutation of all science, when in fact that's simply not the sort of hypothesis scientists even explore typically.
  - parodysbird 2y ago
    He's talking about Bayesian philosophy of science, not science, which ultimately does not rely on Bayesian epistemology.
    - kerkeslager 2y ago
      Agreed--in fact, science doesn't rely on philosophy at all. If the entire field of philosophy disappeared, science would go on functioning just fine. In fact, science has generally been hindered by philosophy--it's seemingly impossible to discuss scientific methodology without some wanker interjecting "well ackchyually nothing is knowable". Animals with nervous systems were learning from observation before humans invented enough language to epistemologize, and will continue to do so with or without philosophers. Bayesian epistemology is an attempt to model why science works--it relies on science, not the other way around.
      - ThomPete 2y ago
        Science do in fact rely on philosophy that's how we got the scientific method.

kerkeslager 2y ago

Bullshit like this is exactly why I think scientists are better philosophers than philosophers are. The text you've quoted, is, frankly, not the writings of an intelligent person. The reason I'm being very blunt about this, is because bullshit like this is actively harmful. Science is fucking important. Science is what resulted in the technology you're using to read this. Science is, with non-negligible probability, the basis of medicine that prevented you from dying before the age of 5 to be able to read this. When philosophers posit that they can inspect the their own navels and find deep truths about the world, they are undermining one of the fundamental pillars of society that holds up so much of the positive changes humans have been able to make. We need to call this what it is--nonsense and misinformation--and stop amplifying its signal. > By ‘Bayesian’ philosophy of science I mean the position that (1) the objective of science is, or should be, to increase our ‘credence’ for true theories, and that (2) the credences held by a rational thinker obey the probability calculus. However, if T is an explanatory theory (e.g. ‘the sun is powered by nuclear fusion’), then its negation ~T (‘the sun is not powered by nuclear fusion’) is not an explanation at all. Therefore, suppose (implausibly, for the sake of argument) that one could quantify ‘the property that science strives to maximise’. If T had an amount q of that, then ~T would have none at all, not 1-q as the probability calculus would require if q were a probability. Of course "the sun is not powered by nuclear fusion" IS an explanation, it's just not an explanation of a phenomenon we observe, which is why most scientists don't believe "the sun is not powered by nuclear fusion". If we observed something about the sun that was not consistent with the hypothesis that it is powered by nuclear fusion, "the sun is not powered by nuclear fusion" would indeed be an explanation of what we were observing. This is all sidestepping the absurdity that Deutsch doesn't seem to understand that "none at all" has a mathematical representation, 0, meaning that if p = 1 - q = 0, then q = 1. This is not difficult math here, folks. > Also, the conjunction (T₁ & T₂) of two mutually inconsistent explanatory theories T₁ and T₂ (such as quantum theory and relativity) is provably false, and therefore has zero probability. Yet it embodies some understanding of the world and is definitely better than nothing. Uh sure, which is why nobody with a brain takes the conjunction of those two things. This isn't a criticism of Bayesian philosophy of science, it's a straw man argument. > Furthermore if we expect, with Popper, that all our best theories of fundamental physics are going to be superseded eventually, and we therefore believe their negations, it is still those false theories, not their true negations, that constitute all our deepest knowledge of physics. Deutsch apparently doesn't know what an approximation is, and instead thinks of correct/incorrect as a binary. Relevant https://hermiene.net/essays-trans/relativity_of_wrong.html https://hermiene.net/essays-trans/relativity_of_wrong.html

marcosdumay 2y ago

Any refutation that depends on the fundamental unknownability of the Universe rules trivially applies to every single philosophy of science. Science must work despite it, or you don't have science. And any other singularity you get from assuming the odds of a hypothesis is infinitely smaller than the odds of it being false is unrealistic. You shouldn't assume that.

hammock 2y ago

Love this. So clearly written. The truest thing we know is how much we don’t know

badRNG 2y ago

> we expect, with Popper, that all our best theories of fundamental physics are going to be superseded eventually This inductive case against scientific knowledge should only serve to decrease our second-order credence in the proposition that we have assigned the highest credence to the scientific hypotheses that most closely correspond with reality. It does nothing to change the fact that, conditional on evidence we currently have, we may very well have correctly proportioned credence.