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Logical positivism

  1. Jan 29, 2008 #1
    Logical positivism states that empirical knowledge and a priori facts are the only meaningful ways to decide on the truth of a statement. If scientific induction is not a priori or empirical (it cant be empirical without using its self to prove its self), then doesnt this mean that a logical positivist could not claim to have any knowledge of anything that he has not directly observed already or considers an a priori fact? ie a logical positivist would have to say that "the sun will rise tomorrow" is a meaningless statement.
  2. jcsd
  3. Jan 29, 2008 #2
    The logical positivist could claim that logical positivism is a basic belief. Also, that can be established with deduction.
  4. Jan 29, 2008 #3
    My point was that a logical positivist cannot claim to know that things which he has observed to happen in the past will continue to happen in the future. It is not possible to prove this by deduction, only induction. There is no (a priori) logical or empirical justification for this kind of induction, it has to be assumed to be true.
  5. Jan 29, 2008 #4
    It is actually quite possible to establish it with deduction.

    1. If the sun does not rise, then nasty consequence X should be observed.
    2. As long as nasty consequence X is not observed, the sun will rise.
  6. Jan 29, 2008 #5
    The fact that something has happened in the past does not mean it will happen in the future. This is a big problem in the philosophy of science and is called the problem of induction. It is unsolved and so no one has managed to solve it by deduction or any other means.
  7. Jan 30, 2008 #6
    The logical positivists took induction for granted. And - let's be honest - so does everyone. You don't need a solution to include induction in your epistemology.

    The content of "the sun will rise tomorrow" would be something like "if you look out your window tomorrow morning you will see the sun". This is empirically verifiable.

    Even so, the view faces big fat problems and is widely rejected. As Duhem/Quine pointed out, you can't verify or refute an empirical proposition as easily as the positivists claimed. You can blame auxiliary premises. What if you look out the window and you don't see the sun? Well maybe the sun hasn't risen, but there's also a chance there's a cloud in the way, or it's foggy, or the window's too dirty...

    The whole idea is wildly implausible.
    Last edited: Jan 30, 2008
  8. Jan 30, 2008 #7
    I just did.
  9. Jan 30, 2008 #8
    You said:

    1. If the sun does not rise, then nasty consequence X should be observed.
    2. As long as nasty consequence X is not observed, the sun will rise.

    I can't see how to interpret this as a deductive argument. Let me guess:

    Null hypothesis (sun rises every day) would be disproved by X
    X has not been observed
    Null hypothesis is true.

    This isn't valid - the fact that the hypothesis has not yet been refuted is not a reason to conclude it is true.
  10. Jan 30, 2008 #9
    No, it is a standard modus tollens argument.

    A -> B

    1. If the sun will not rise tomorrow, then testable prediction X.
    2. Testable prediction X fails.
    3. Therefore, the sun will rise tomorrow.
  11. Jan 30, 2008 #10
    I don't think "the sun will not rise tomorrow" entails predictions that are testable now. What if it vanishes in a sudden blip a moment before sunrise?
  12. Jan 30, 2008 #11
    It would take 8.3 minutes for use to notice. Sun rise is most often connected to the rotation of the earth.
  13. Jan 30, 2008 #12
    Okay, let's say either a) the sun vanishes 8.3 minutes before predicted sunrise or b) the Earth stops rotating a moment before predicted sunrise. Construct your own examples at will.

    Such an event doesn't entail any predictions that are testable in the present - a time before it has happened.
  14. Feb 1, 2008 #13
    Wouldn't the 'true' logical positivist agree with you and avoid the statement. Perhaps putting in logical positivst phrasiology thus:

    The sun has risen reliably on the previous 365*(4.5 billion) occasions. Baring extremely rare occurances, it will rise tomorrow.

    Somehow his statement conveys the same surity without entering the trap of the obvious contradiction.
  15. Feb 1, 2008 #14
    The problem of induction is explaining why the fact that it has risen on every other occasion makes it any more likely to rise tomorrow. It seems an obvious thing to assume but in fact it is difficult to justify. I cant see how it is justifiable by empirical means or a priori means (unless taken to be a priori in itself). Most obvious attempts to justify actually implicitly use induction in their argument, for example "induction seems to work, so we may as well use it", you assume because induction has worked well in the past, it will work well in the future.
  16. Feb 1, 2008 #15
    I am playing the roll of a logical positivist trying to get out of your trap. Looking back at my first attempt to do this I find I have made a mistake. I cannot make the first statement about the reliability of previous sunrises beyond my own experience, (Unless I am allowed to take the word of others as empirical). So now I have to say that "the sun rose reliably on the previous 15875 occasions." Next I change my second condition in defference to your argument and say "provided things continue in accord with my empirical records", and then I finnish with the same phrase, "the sun will rise tomorrow." Does this get me out of the trap or have I just abandoned my creed? In other words, given the acknowledged lack of either empirical or a priori knowledge attributable to the future, this is all that a true logical positivist would say.
  17. Feb 1, 2008 #16
    What makes you think the fact that the sun having risen on every other day in the past has any bearing at all on whether it will rise tomorrow? The problem in your argument is the condition "provided things continue in accord with my empirical records". For a logical positivist, as far as i can see they would have to say this statement is neither verifiable empirically or by a priori means at the present moment, and hence they would have to concede that the question is "meaningless".
  18. Feb 1, 2008 #17
    I think that the logical positivist does agree with you, and that is why he used the "if" clause in the second part of his statement. The history of occurances are empirical, but the logical positivist uses the empirical history purely as a point of depature, to allow him to say all he can logically say about the future.

    Effectively what he is saying is, "Provided, the pattern of past empirical events continues through tomorrow, the sun will rise tomorrow."

    He is saying all he can possibly say without ceasing to be a true logical positivist.
  19. Feb 1, 2008 #18
    But little nuances like this does not really matter. As someone once said, "call me when the sun doesn't rise tomorrow."
  20. Feb 2, 2008 #19
    I am just trying to point out what I consider to be a serious weakness in adopting a logical positivist standpoint. I agree that the sun will rise tomorrow, which is why I dont accept this view. I dont think that it is practical to only believe in things that you have observed empirically or consider a priori. The statement "Provided, the pattern of past empirical events continues through tomorrow, the sun will rise tomorrow." is fine but without induction you have no reason at all to prefer this outcome to the sun not rising. You could just as well say "Provided, the pattern of past emirical events doesnt continue through tomorrow, the sun wont rise tomorrow" which is also correct.
    Little nuances like this don't matter in everyday life, but when trying to establish a fundamental philosophy on what you can and can't accept to be true, I certainly think they do.
  21. Feb 2, 2008 #20
    If I am playing the roll of the logical positivist, I have to agree with you. I am on untennable ground on a day to day general life basis because so much of what we use to structure our lives has to be taken for granted. It cannot be logically derived from our yesterday's. So in the strict sense, I have no basis on which to assume that the sun will rise tomorrow, and yet I still make plans to visit my friends during daylight hours.

    However, I am a contradiction, if, and only if, I believe that it is a "fact" that the sun will rise tomorrow, which I do not. In another thread the question of a proof for the existence of the future has been asked and this question ties in with that question. No proof for the existence of the future is, as yet, available. If I cannot cite a proof for the existence of the future, then I certainly cannot prove that an event in that unproven future will take place.

    But am I not entitled to take reference from the empirical past, in the form of probability, pure likelyhood. "Provided things continue as they have always done" seems to me to contain a higher probability than, "Provided things do not continue as they have always done."
    Last edited: Feb 2, 2008
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