5 ms·

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.
        lisper 8y ago
        > you can learn to hit a target reliably from any distance Not without developing an explanatory theory you can't. Read Deutsch.
        thaumasiotes 8y ago
        > Not without developing an explanatory theory you can't. This is absolutely false as a matter of historical fact; the theory always follows a period of trial-and-error in which you learn how to hit the target by raw experimentation. There's a pretty simple reason for this, which is that the trial-and-error approach is easy to execute. > Read Deutsch. Any reason I should do this? "Read Deutsch" isn't exactly a compelling argument against the idea that theories derive their authority from a track record of success, as opposed to something more non-inductive such as divine ordination.

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.
        lisper 8y ago
        > you can learn to hit a target reliably from any distance Not without developing an explanatory theory you can't. Read Deutsch.
        thaumasiotes 8y ago
        > Not without developing an explanatory theory you can't. This is absolutely false as a matter of historical fact; the theory always follows a period of trial-and-error in which you learn how to hit the target by raw experimentation. There's a pretty simple reason for this, which is that the trial-and-error approach is easy to execute. > Read Deutsch. Any reason I should do this? "Read Deutsch" isn't exactly a compelling argument against the idea that theories derive their authority from a track record of success, as opposed to something more non-inductive such as divine ordination.