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Occam's razor?

david_shaw 16y ago
> Occam's razor? Yup, came here to post just that. Additionally, you can take some cards from Skeptics in general, and assert that extraordinary claims require extraordinary evidence. Burden of proof lies not on the skeptic, but on the one with the ludicrous claim.
- marcamillion 16y ago
  Can you explain in simply terms what Occam's razor is? I Wikipedia'd it, but the definition was too dense. It could be as a result of me being tired...but I couldn't quite understand it. Thanks.
  - david_shaw 16y ago
    Sure. Occam's razor just means that the most simple explaination is the most likely. For example, a car accident could be caused by a driver attempting to SMS while driving, or an extraterrestrial life form stealing the drivers' thoughts and consciousness temporarily. Occam's razor would suggest that the simplest explaination (in this case, texting) is more likely to be the correct explaination, rather than a more complicated (though technically still possible) explaination. Occam's razor has its place in science (where it consistently holds true), but also applies to things like conspiracy theories.
    - hasenj 16y ago
      I'm not sure that's a good example. "Simple" is a subjective term. The way I understand it, the simplest explanation is not the one that "makes sense to me", but the one with less unneeded baggage. And it's not a principle of logic, but a general guideline. So take it with a grain of salt. Consider a pen falling down, and consider these explanations: 1. Things always fall down 2. There exists gravitational force between bodies 3. Relativity's explanation about how bodies bend spacetime (which frankly I don't really understand). #1 is the simplest, but the least accurate. #3 is more complex but more accurate. And when I say it's more complex, I mean relative to #1 of course. Relativity (from what I understand) is actually simple (once you have the right mental model), but to the uninitiated, it appears to be rather complex, and #1 would appear to be much simpler. But, it would be wrong to dismiss Relativity based on "Occam's razor".
      - newt 16y ago
        "Simple" is a subjective term. Which is why it's sometimes stated as "Entities should not be multiplied unnecessarily" - i.e pick the explanation with the fewest moving parts. That's less subjective, assuming you can agree on how to count the entities. 1. Things always fall down This is not actually an explanation at all, it just restates the observation. 2. There exists gravitational force between bodies Newton's inverse square law of gravitation is simpler than relativity, and it's good enough for a lot of uses. But it is not a viable explanation either, since it does not fit exactly with observed reality - it does not handle the edge cases of very fast or very heavy stuff.
        hasenj 16y ago
        > This is not actually an explanation at all, it just restates the observation It's an explanation for "why the pen fell down". It states a law whereby "things always fall down".
        newt 16y ago
        Ok, it generalises the observation to other things as well.
        newt 16y ago
        To go further, What is and what isn't an "explanation" ? "Things always fall down" doesn't add much. It says that the observation can be repeated. Newton's law says more than "There exists gravitational force between bodies" which isn't much of an improvement over "things always fall down". Newton provided a mathematical formula to measure it, which, as best as could be seen in Newton's time, fit exactly with reality, applying from apples up to planets. http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gra... This makes testable, measurable predictions about "why things fall down", i.e. "things fall down because all things obey the law of universal gravitation as given in the formula...". But it doesn't even begin to explain why there is gravity all rather than no gravity. Science is largely silent about this category of question of meaning not measurement - it observes reality and predicts based on extrapolating from existing observations. Other explanations of "why" are hardly much better - "gravity exists because God said so" aren't very satisfying since you can't test it or infer anything from it.

Occam's razor?

> Occam's razor? Yup, came here to post just that. Additionally, you can take some cards from Skeptics in general, and assert that extraordinary claims require extraordinary evidence. Burden of proof lies not on the skeptic, but on the one with the ludicrous claim.

marcamillion 16y ago
Can you explain in simply terms what Occam's razor is? I Wikipedia'd it, but the definition was too dense. It could be as a result of me being tired...but I couldn't quite understand it. Thanks.
- david_shaw 16y ago
  Sure. Occam's razor just means that the most simple explaination is the most likely. For example, a car accident could be caused by a driver attempting to SMS while driving, or an extraterrestrial life form stealing the drivers' thoughts and consciousness temporarily. Occam's razor would suggest that the simplest explaination (in this case, texting) is more likely to be the correct explaination, rather than a more complicated (though technically still possible) explaination. Occam's razor has its place in science (where it consistently holds true), but also applies to things like conspiracy theories.
  - hasenj 16y ago
    I'm not sure that's a good example. "Simple" is a subjective term. The way I understand it, the simplest explanation is not the one that "makes sense to me", but the one with less unneeded baggage. And it's not a principle of logic, but a general guideline. So take it with a grain of salt. Consider a pen falling down, and consider these explanations: 1. Things always fall down 2. There exists gravitational force between bodies 3. Relativity's explanation about how bodies bend spacetime (which frankly I don't really understand). #1 is the simplest, but the least accurate. #3 is more complex but more accurate. And when I say it's more complex, I mean relative to #1 of course. Relativity (from what I understand) is actually simple (once you have the right mental model), but to the uninitiated, it appears to be rather complex, and #1 would appear to be much simpler. But, it would be wrong to dismiss Relativity based on "Occam's razor".
    - newt 16y ago
      "Simple" is a subjective term. Which is why it's sometimes stated as "Entities should not be multiplied unnecessarily" - i.e pick the explanation with the fewest moving parts. That's less subjective, assuming you can agree on how to count the entities. 1. Things always fall down This is not actually an explanation at all, it just restates the observation. 2. There exists gravitational force between bodies Newton's inverse square law of gravitation is simpler than relativity, and it's good enough for a lot of uses. But it is not a viable explanation either, since it does not fit exactly with observed reality - it does not handle the edge cases of very fast or very heavy stuff.
      - hasenj 16y ago
        > This is not actually an explanation at all, it just restates the observation It's an explanation for "why the pen fell down". It states a law whereby "things always fall down".
        newt 16y ago
        Ok, it generalises the observation to other things as well.
        newt 16y ago
        To go further, What is and what isn't an "explanation" ? "Things always fall down" doesn't add much. It says that the observation can be repeated. Newton's law says more than "There exists gravitational force between bodies" which isn't much of an improvement over "things always fall down". Newton provided a mathematical formula to measure it, which, as best as could be seen in Newton's time, fit exactly with reality, applying from apples up to planets. http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gra... This makes testable, measurable predictions about "why things fall down", i.e. "things fall down because all things obey the law of universal gravitation as given in the formula...". But it doesn't even begin to explain why there is gravity all rather than no gravity. Science is largely silent about this category of question of meaning not measurement - it observes reality and predicts based on extrapolating from existing observations. Other explanations of "why" are hardly much better - "gravity exists because God said so" aren't very satisfying since you can't test it or infer anything from it.