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To predict is to explain?

  1. Aug 26, 2004 #1
    The goodness of a scientific theory,as Relativity or QM, is related to its prediction's power.

    But when could we assert that we explain anything? Only in basis to prediction (or "retrodiction") ?
  2. jcsd
  3. Aug 26, 2004 #2
    Words only have demonstrable meaning according to their function in a given context.

    Is that a good enough explanation for you? :0)
  4. Aug 26, 2004 #3
    No. You ever talk about context. Well. Choose one.
  5. Aug 26, 2004 #4
    When is an explanation not an explanation? When no one can understand it, not even the author, or whenever someone does not see it as an explanation.

    "Goodness" is a value judgment, not a scientific assessment. Exactly what is the goodness of being able to predict, for example, that you cannot predict something? It has no demonstrable inherent "goodness" and some might say it is utterly useless. It just depends upon who is making the value judgment.
  6. Aug 27, 2004 #5
    Predicting that you cannot predict something can be very valuable, as it narrows down the field of variables you explore in a system. I see no reason to pick on the original posters use of the word "goodness." Maybe value or scientific value might have avoided the problem, but surely everyone understood what he meant.

    Physics is judged by it's ability to predict past, present and future variables. To answer the original question, I do not see physics as explaining anything, nor do I think it should. I'm not convinced things around us can even be "explained" the way people use the word, by science or philosophy.
  7. Aug 27, 2004 #6
    It seems that that's the case with Gödel's theorem...
    Yes. Strictly, "goodness" is a value judgement. Strictly, explanation isn't a scientific term. Strictly, we only could talk in a mathematical language. Alternatively, we would must previously agree about the significance of each term that we use as prediction, explanation, goodness...
  8. Aug 27, 2004 #7
    I find your answer very interesting. It is clear that a scientific theory must be capable of prediction. But why must "explanation" be out of Science?
  9. Aug 27, 2004 #8
    My answer would be that I define science as that knowledge that comes from the scientific method. I do not believe the scientific method can always appropriately distinguish between various explanations. What's more, explanations can be invalidated by new discoveries, whereas the experiments that created them sometimes aren't.

    The "explanation" that was produced by newtonian mechanics is clearly disproven in light of 20th century physics. An yet I use newtonian mechanics all the time. It works great within the realm of the experiments done to prove it an acceptable theory. I could sit around worrying about whether the explanation derived from a new theory is good or bad, but who cares? The explanation is temporary. It's predictive power is not.

    It is also possible to insert extraneous information into an explanation that does not affect the nature of its predictions. Scientists respond to this by employing Occam's razor; but Occam's razor is not science, it is a philosophical tool. How can one justify using a tool to determine what is "science" that is not based on the scientific method when distinguishing between two explanations that both rely on predictions found by the scientific method?

    I don't mean to suggest that creating non-mathematical interpretations of theories is useless. I think it is a useful tool for conducting science. Of course, so is a computer, but that doesen't mean a computer is science, or that science is responsible for the quality of computers manufactured.
  10. Aug 27, 2004 #9
    I prefer to define science as the pursuit of knowledge of the natural universe, using various empirical and logical methods (the scientific method being only one, yet most popularly known, variety). The "bits" of knowledge are facts, and the facts are inductively analyzed to form a scientific theory. Scientific theories are proposed explanations of the facts and are inherently tentative and fallible by virtue of the induction process that was involved in their creation.

    As time passes, as more research opens up new possibilities, as new brains step up to the plate, scientific theories should become more and more aligned with the "true" underlying explanation of the natural universe (aka Theory of Everything). This process has been observed when comparing Newton's Law of Gravity with General Relativity. Newton's Law of Gravity is very accurate and useful...to a point. General Relativity is a "sharper" theory that seems to be more closely aligned with the "true" explanation. Some other theory, Theory X, may turn out to be "sharper" than General Relativity, thereby unseating Einstein.

    The progress may be asymptotic, in the sense that we may never actually reach the "true" explanation, but the pursuit itself is really where much of the aesthetic pleasure, excitement, and "goodness" of science is located IMO.
  11. Aug 30, 2004 #10
    That is an interesting difference. :approve:
    If I understand your position, the scientific knowledge would be linked directly to the prediction's power of scientific theories, whereas explanation could imply other factors, as you show with the reference to the Occam's razor.
    Prediction's power would be strictly scientific
    Explanation would be also related with the personal and historical "Weltanschauung". Are you in agreement?
  12. Aug 30, 2004 #11
    I agree completely with your asymptotic image of progress. :smile:
    I find very interesting your reference to the relationship between "the pursuit" and the "aesthetic pleasure". From my viewpoint, as I posed in other thread, the relationship of this aesthetic pleasure with scientific activity would arise from the fitness of theories to Nature in a form of Aristotle's mimesis (Poetics).
  13. Sep 4, 2004 #12
    Prediction, description, explanation and understanding. Are all they scientific terms?
  14. Oct 4, 2004 #13
    Knowledge and QM

    QM is a good theory because of it is highly predictive. That is Science. But there are diverse "interpretations" of QM. Are these interpretations scientific or philosophical approachs? :rolleyes:
  15. Oct 5, 2004 #14


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    Well some good scientists are obsessed with them. I don't think there's a big nanny who says what science is or is not. Science is what the people who do it say it is. And if there is disagreement on what they say, so be it.
  16. Oct 6, 2004 #15
    That is a circular argument. Scientists would be also the people that do Science. Philosophy and Science are different things and this difference would apply also to interpretations of quantum mechanics.
  17. Oct 6, 2004 #16


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    So, how can science be defined, in terms that have high relevance to the real world of what scientists do?
    Last edited: Oct 6, 2004
  18. Oct 6, 2004 #17


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    No it isn't circular, because science is historical (or if you prefer, dialectical), so the definitions of one generation react with the self definition of the next to update the definition of science. If you had asked Newton what he was doing you would have gotten a very different answer than if you posed the same question to Maxwell, Einstein, or Witten.
  19. Oct 7, 2004 #18
    Probably, Newton and Maxwell would say that they were doing Philosophy of Nature
    Yes, Science and definition of Science are made in a historical context. But if Science is that scientists do and scientists do Science, the expression seems to be circular.
    There are problems with definitions when Science is very entangled with Philosophy, and such is the case in QM interpretations. When a scientist express his worldview he is not doing science, although his worldview result from his scientific activity.
  20. Oct 7, 2004 #19
    I don't know now any definition absolutely valuable.
    Science would be by one hand a work: the use of the scientific method to explore the Nature, being the scientific method one based in experimentation, observation, logic deduction and induction. A key factor in this method would be the communication in a common language, being mathematics the best form of expression.
    On the other hand, Science would be the whole of knowledge obtained by the scientific method. This knowledge would be the substrate of predictive theories.
  21. Oct 7, 2004 #20


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    IOW, wherever we can determine that these elements have been used (consciously? unknowingly??*), we can call the activity 'science'?
    So without maths it's just not science? Or the use of math is a heuristic guide?
    So are the predictive theories then part of science? or a consequence of science? or a critical component?

    *this point is quite important; depending on how strictly you constrain 'observation, logic deduction and induction', you could argue that pre-historic groups of humans 'did' science - they hunted, they planted and harvested crops, they found and used 'medicinal plants'. This also begs the question of whether the crux of science is the process ('the scientific method') or the outcome ('the body of knowledge acquired') ... or both ... or neither.
  22. Oct 7, 2004 #21
    I believe that we can use the term Science only when we talk about a conscious activity. Science searchs causes. It is reductive. Empirical knowledge is not enough to have Science. Empirical knowledge can be also explained in a mythological context.

    Yes. Maths is Science. And a tool (calculus). And a language. There is of course a scientific, not mathematical language to communicate findings. But mathematical language would be the most adequate form of expression in Science. As Lord Kelvin said: "When you measure what you are speaking about and express it in numbers, you know something about it, but when you cannot express it in numbers your knowledge about is of a meagre and unsatisfactory kind"

    I think that prediction (and perhaps postdiction) is a key part of Science. Scientific activity results in theories and theories are valuable if their predictions can be confirmed by observation or experimentation. Prediction is a critical component.
  23. Oct 7, 2004 #22
    What could be the effects of the INCREASE or DECREASE in the number of visual organs on the OUTWARD QUALITY of the object of the human perception? For example, if you remove some of the visual organs from the body or add more to it, or redesign them, will it improve or decrease our ability to perceive the world? I have asked this question elsewhere: can concepts form in the perceiver without first getting acquainted with the external world to model and extrapolate from it? If concepts are models of realities in the external world, why should there be any surprises when objective facts or truths are deduced from them? Or simply, why should it come as a surprise when we are able to extrapolate and predict from conceptual facts? Could the whole process not be that:

    We map the external world onto self and back onto the external world?

    could we then not say that we carry models of realities of the external world in our heads, with equally the ability to modify and conceptualise them? That for example, we carry the concept of a unicorn in our heads as a modification of the concept of a horse in our heads which in turn is a conceptualised model of a real horse in the external world? This now underpins the question that I have asked above and elsewhere:

    Would a human being come to have the concept of a unicorn, without first coming into a physical (visual) contact with a real horse, or with a four-legged animal, in the external world?
    Last edited: Oct 8, 2004
  24. Oct 8, 2004 #23
    An even deeper question is what would be science if we modified the neural circuitry of our brain/mind ? We could eventually learn how the mind organizes thoughts, information, emotions and memory and change the wiring in many different ways. A mind that is organized completely differently and maybe uses memory and thought completely differently would perceive another universe and another physics.

    In that case, that "alien" mind could describe, explain and predict a human according to their physics and at the same time a human describe this alien with our science physics. Which is the real science ? Both because science is a function of the mind investigating and the reality (atually there could be trillions of different minds and physics ..)

    An 8 men
  25. Oct 8, 2004 #24


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    Welcome to Physics Forums eighth man!

    Could you please say more about why you think a differently wired brain could (maybe) perceive 'another universe and another physics'? After all, unless you also changed the eyes, ears, etc to process cosmic rays, magnetic fields, neutrinos, etc, the brain would still be limited to processing the same sensory inputs as ours are. Re-wiring might indeed lead to an ability to calculate, without conscious thought, to 97 decimal places, the 3745th power of e (and other amazing things computers can do), but that's not another universe.
  26. Oct 8, 2004 #25
    No, I'm taking it to a much higher level of abstraction. Yes our physics with our mind is correct and coherent. I am thinking of a rewired mind that thinks very differently, that uses memory very differently , in other words the way our mind organizes information could be modified to do it very differently. Now I agree that this is quite abstract because no one knows how this mind would work or what its mental states would be, not to mention emotional, but I think that in the future modified minds will emerge.

    At that point there is no telling how the world could be viewed and perceived. Up to now all reality has been anayzed with a fixed mind M,
    by modifying minds this one reality could be analyzed with Mn different minds Mn x R1, and eventually Rn realities, then there would be Mn x Rn different universes (eventually trillions).

    Even imagining a mind that has an intermediate level that deals with reality and transforms all to a higher level, and the alien mind only deals with the higher level, just in this case it could no longer be understood by us at all, and anyways this alien mind could analyze and view us humans and all reality according to completely different rules that are valid in that "Mind + Universe" where universe is a function of mind.

    An Ape
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