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... but it is not valid to conclude that the sun will continue to rise in the east forever. (It won't.) Can you use induction in a valid way to invalidate indu

... but it is not valid to conclude that the sun will continue to rise in the east forever. (It won't.) Can you use induction in a valid way to invalidate induction?

lisper 8y ago
No. Induction is invalid, full stop. It cannot be validly used to demonstrate anything.
- sonusario 8y ago
  Then how do you know that the sun won't rise forever?
  - lisper 8y ago
    Physics. In about 5 billion years the sun will become a red giant and destroy the earth. https://www.e-education.psu.edu/astro801/content/l6_p2.html https://www.e-education.psu.edu/astro801/content/l6_p2.html
    - sonusario 8y ago
      So induction was not used to determine this?
      - lisper 8y ago
        No.
        sonusario 8y ago
        Then what form of reasoning was used? You stated that we cannot validly claim that the sun will rise forever just because we've observed it rise in the east every day for the last few billion years. Then you cite stellar observations that we use to claim that the sun will become a red giant and destroy the earth. What are the differences in those observations that make one invalid induction and the other not?
        lisper 8y ago
        > stellar observations that we use to claim that the sun will become a red giant and destroy the earth No. We have never observed a star become a red giant. That process takes millions of years, and we have only been doing astronomy for a few hundred. The reason we know that the sun will become a red giant is not because we have ever observed this process happen, but because we have an explanatory theory of how stars work. Going into detail on how that process works is a little too long for an HN comment. If you really want to know, read David Deutsch's "The Fabric of Reality", particularly chapter 7. (Or go straight to the source and read Karl Popper.)
        thaumasiotes 8y ago
        We have an explanatory theory of how stars have worked in the past. But we don't have a justification, other than induction, for believing that that theory will remain valid into the future.
        lisper 8y ago
        > we don't have a justification, other than induction Yes, we do. Scientific theories are justified by their explanatory power. Read Deutsch.
        thaumasiotes 8y ago
        How much of that explanatory power is derived from explaining things that have happened in the past, vs how much from explaining things that have happened in the future? You can fire a cannonball and observe a parabolic arc, you can learn to hit a target reliably from any distance, and you can develop a unified theory of gravity, air resistance, and the rotation of the earth that explains why firing at such-and-such angle with such-and-such amount of power will strike a target at a fixed location. That theory will allow you to hit targets reliably even in firing situations that you've never encountered in the past. But induction is your only justification for believing that gravity, air resistance, and the rotation of the earth will affect cannonballs and missiles the same way tomorrow as they did yesterday.
- mrec 8y ago
  The point sonusario is making is that your assertion about the future behaviour of the Sun is based on our understanding of physics, and physics is itself inherently inductive - it's an abstraction and formalisation of empirical experience. If we'd consistently made very different observations of the world, we'd have come up with different physics, which would make different predictions. In my view saying things like "induction is invalid" is a bit of dead end, rather like Cartesian doubt. It's not that it's wrong, more that you can't go anywhere interesting from there, unless you abandon your own principles and start wibbling about God and the natural light and pineal glands.
  - lisper 8y ago
    > physics is itself inherently inductive No, it isn't. It is explanatory. You need to read Deutsch and/or Popper. The argument is too long to reproduce in an HN comment.
- pdonis 8y ago
  > Induction is invalid Can you rephrase this without using the word "induction"? Since that word seems to be confusing a lot of people in this discussion. My attempt at rephrasing, based on what it seems like you are using "induction" to mean, would be: it is always invalid to reason that the future will be exactly like the past. Or perhaps: it is always invalid to reason that our future data will show exactly the same patterns as our past data. If this is what you are using "induction" to mean, then of course you are correct; but I don't think this is what others in this discussion are using "induction" to mean.
  - lisper 8y ago
    Good grief, doesn't anyone on HN understand context any more? The top-level post here is "The new riddle of INDUCTION". When I use the word "induction" I mean what it means in the title, which is explained at great length in the paper. I mean this: https://en.wikipedia.org/wiki/Inductive_reasoning https://en.wikipedia.org/wiki/Inductive_reasoning Not this: https://en.wikipedia.org/wiki/Mathematical_induction https://en.wikipedia.org/wiki/Mathematical_induction
    - sonusario 8y ago
      Does explanatory theory make use of observation? Because based on the the wiki page for inductive reasoning, if you use observations for evidence, then you are using inductive reasoning to some capacity.
      - lisper 8y ago
        Well, what I really mean by "induction" is what it means in the paper pointed to by the OP, i.e. the paper entitled "The new riddle of induction." I pointed to the wikipedia article just to contrast that with mathematical induction, which is NOT what I or anyone else is talking about here. Yes, explanatory theories rely on observations. But they are not just straightforward extrapolations of the form, "Because we have observed something N times (e.g. we have seen N green emeralds) we can reliably conclude that we will continue to observe it (e.g. all emeralds are green)."
jonbarker 8y ago
Not sure, but I can use deduction: 1) If induction is valid, then it follows that we can use induction to reason about the world. 2) But we can't use it to reason about the world, 3) so it isn't valid. (Modus Tollens) This is valid, but not necessarily sound. Soundness implies that first two statements (premises) are also true. The second premise is clearly not true, because we use induction to reason all the time. So the conclusion #3, while it follows as a valid argument, cannot be said to be a 'sound conclusion.'
- lisper 8y ago
  > we use induction to reason all the time Yes, people use all kinds of invalid reasoning techniques and fall victim to a wide variety of logical fallacies and cognitive biases. That doesn't mean that any of them are valid.
  - jonbarker 8y ago
    I think you are expecting the term 'validity' to mean more than what it technically means to people in philosophy, which is that it 'adheres to the form of either Modus Ponens or Modus Tollens'. Colloquially it has come to mean more like what soundness means, which is valid but also with true premises.
    - lisper 8y ago
      I don't want to quibble over terminology. Inductive reasoning is wrong. Mistaken. Bogus. Intellectually bankrupt. Utterly without redeeming value of any kind. As likely to lead to correct conclusions as reading Tarot cards (which is to say, the probability is higher than 0, but not by a wide enough margin to have any utility).

... but it is not valid to conclude that the sun will continue to rise in the east forever. (It won't.) Can you use induction in a valid way to invalidate induction?

lisper 8y ago

No. Induction is invalid, full stop. It cannot be validly used to demonstrate anything.

sonusario 8y ago
Then how do you know that the sun won't rise forever?
- lisper 8y ago
  Physics. In about 5 billion years the sun will become a red giant and destroy the earth. https://www.e-education.psu.edu/astro801/content/l6_p2.html https://www.e-education.psu.edu/astro801/content/l6_p2.html
  - sonusario 8y ago
    So induction was not used to determine this?
    - lisper 8y ago
      No.
      - sonusario 8y ago
        Then what form of reasoning was used? You stated that we cannot validly claim that the sun will rise forever just because we've observed it rise in the east every day for the last few billion years. Then you cite stellar observations that we use to claim that the sun will become a red giant and destroy the earth. What are the differences in those observations that make one invalid induction and the other not?
        lisper 8y ago
        > stellar observations that we use to claim that the sun will become a red giant and destroy the earth No. We have never observed a star become a red giant. That process takes millions of years, and we have only been doing astronomy for a few hundred. The reason we know that the sun will become a red giant is not because we have ever observed this process happen, but because we have an explanatory theory of how stars work. Going into detail on how that process works is a little too long for an HN comment. If you really want to know, read David Deutsch's "The Fabric of Reality", particularly chapter 7. (Or go straight to the source and read Karl Popper.)
        thaumasiotes 8y ago
        We have an explanatory theory of how stars have worked in the past. But we don't have a justification, other than induction, for believing that that theory will remain valid into the future.
        lisper 8y ago
        > we don't have a justification, other than induction Yes, we do. Scientific theories are justified by their explanatory power. Read Deutsch.
        thaumasiotes 8y ago
        How much of that explanatory power is derived from explaining things that have happened in the past, vs how much from explaining things that have happened in the future? You can fire a cannonball and observe a parabolic arc, you can learn to hit a target reliably from any distance, and you can develop a unified theory of gravity, air resistance, and the rotation of the earth that explains why firing at such-and-such angle with such-and-such amount of power will strike a target at a fixed location. That theory will allow you to hit targets reliably even in firing situations that you've never encountered in the past. But induction is your only justification for believing that gravity, air resistance, and the rotation of the earth will affect cannonballs and missiles the same way tomorrow as they did yesterday.
mrec 8y ago
The point sonusario is making is that your assertion about the future behaviour of the Sun is based on our understanding of physics, and physics is itself inherently inductive - it's an abstraction and formalisation of empirical experience. If we'd consistently made very different observations of the world, we'd have come up with different physics, which would make different predictions. In my view saying things like "induction is invalid" is a bit of dead end, rather like Cartesian doubt. It's not that it's wrong, more that you can't go anywhere interesting from there, unless you abandon your own principles and start wibbling about God and the natural light and pineal glands.
- lisper 8y ago
  > physics is itself inherently inductive No, it isn't. It is explanatory. You need to read Deutsch and/or Popper. The argument is too long to reproduce in an HN comment.
pdonis 8y ago
> Induction is invalid Can you rephrase this without using the word "induction"? Since that word seems to be confusing a lot of people in this discussion. My attempt at rephrasing, based on what it seems like you are using "induction" to mean, would be: it is always invalid to reason that the future will be exactly like the past. Or perhaps: it is always invalid to reason that our future data will show exactly the same patterns as our past data. If this is what you are using "induction" to mean, then of course you are correct; but I don't think this is what others in this discussion are using "induction" to mean.
- lisper 8y ago
  Good grief, doesn't anyone on HN understand context any more? The top-level post here is "The new riddle of INDUCTION". When I use the word "induction" I mean what it means in the title, which is explained at great length in the paper. I mean this: https://en.wikipedia.org/wiki/Inductive_reasoning https://en.wikipedia.org/wiki/Inductive_reasoning Not this: https://en.wikipedia.org/wiki/Mathematical_induction https://en.wikipedia.org/wiki/Mathematical_induction
  - sonusario 8y ago
    Does explanatory theory make use of observation? Because based on the the wiki page for inductive reasoning, if you use observations for evidence, then you are using inductive reasoning to some capacity.
    - lisper 8y ago
      Well, what I really mean by "induction" is what it means in the paper pointed to by the OP, i.e. the paper entitled "The new riddle of induction." I pointed to the wikipedia article just to contrast that with mathematical induction, which is NOT what I or anyone else is talking about here. Yes, explanatory theories rely on observations. But they are not just straightforward extrapolations of the form, "Because we have observed something N times (e.g. we have seen N green emeralds) we can reliably conclude that we will continue to observe it (e.g. all emeralds are green)."

jonbarker 8y ago

Not sure, but I can use deduction: 1) If induction is valid, then it follows that we can use induction to reason about the world. 2) But we can't use it to reason about the world, 3) so it isn't valid. (Modus Tollens) This is valid, but not necessarily sound. Soundness implies that first two statements (premises) are also true. The second premise is clearly not true, because we use induction to reason all the time. So the conclusion #3, while it follows as a valid argument, cannot be said to be a 'sound conclusion.'

lisper 8y ago
> we use induction to reason all the time Yes, people use all kinds of invalid reasoning techniques and fall victim to a wide variety of logical fallacies and cognitive biases. That doesn't mean that any of them are valid.
- jonbarker 8y ago
  I think you are expecting the term 'validity' to mean more than what it technically means to people in philosophy, which is that it 'adheres to the form of either Modus Ponens or Modus Tollens'. Colloquially it has come to mean more like what soundness means, which is valid but also with true premises.
  - lisper 8y ago
    I don't want to quibble over terminology. Inductive reasoning is wrong. Mistaken. Bogus. Intellectually bankrupt. Utterly without redeeming value of any kind. As likely to lead to correct conclusions as reading Tarot cards (which is to say, the probability is higher than 0, but not by a wide enough margin to have any utility).