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Old 16th August 2011, 06:30 AM   #105
Dave Rogers
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Originally Posted by stevea View Post
I never said ONE "corrrect" hypothesis. The assumption is fully warranted and commonly observed. For any set of data we can create an infinite number of differing hypotheses that match these (and all other) observations. (Some of) these "currently accurate" hypotheses will make differing predictions under other conditions. So clearly some of the classes of 'currently accurate' hypotheses will later be verified and others falsified if/when we test.
Agreed. Until the hypotheses are tested under these newer conditions, we cannot determine in advance which will fail, so at the earlier stage of knowledge we cannot select between them other than by some arbitrary criterion.

Originally Posted by stevea View Post
Yes - obviously some hypotheses that match the current observations contradict each other in other domains and ranges of conditions. So selecting any one hypothesis without additional work will be certain to lead to errors. Therefore Occam's Razor often sleects a hypothesis that is later falsified. Occam's razor is intended to be a 'neutral' selection rule, however the definition of "fewer presuppositions' or "simpler" doesn't bear close scrutiny. We should at least have a schema that doesn't reject potentially accurate hypotheses, as Occam's Razor clearly does.
The problem with that suggestion is that there must be an infinite number of potentially accurate hypotheses, and we cannot maintain all of them. If we maintain less than an infinite number, it seems a waste of effort to maintain more than one.

Originally Posted by stevea View Post
Wrong question. It's which of millions of hypotheses that "accurately predict all known data" shall we accept ?
No, it's which of an infinite set of hypotheses shall we accept? It's trivial to construct, from any hypothesis, a more complex hypothesis which explains all known data equally well, and this process may be repeated indefinitely.

Originally Posted by stevea View Post
Occam'sR requires the one with the fewest presuppositions, but that means we will be choosing hypotheses that will later fail, forcing revision. Perhaps we should consider the set of ALL supported hypotheses.
As will any other criterion that isn't based on knowledge that we do not have. So we can't consider the set of all supported hypotheses, because it's a task of infinite complexity.

Originally Posted by stevea View Post
Yes - and this second 'better' hypothesis invalidates the first forcing revisions. The first hypothesis was wrong all along, and it was undoubtedly be used to make erroneous or at last imperfect extrapolations and predictions. It could be a costly blunder to accept the 'simplest' hypothesis rather than considering all supported hypotheses.
OK, let's talk about cost. It may, indeed, be a costly blunder to accept the simplest hypothesis rather than considering all supported hypotheses. However, it must inevitably be a costly blunder to consider all supported hypotheses, for two reasons: firstly, some of them will at a later time be falsified, leading to your retrospective conclusion that any use of them was a blunder even if it didn't lead to any significantly inaccurate predictions of phenomena; and secondly, without the choice imposed by Occam's Razor, every phenomenon requires not a single, but an infinite set of explanations, and every calculation an infinite set of iterations. Without some selection criterion, no progress will ever be possible, because no calculation can ever be completed.

Originally Posted by stevea View Post
You miss the point. I am NOT creating any new requirement, and I am not suggesting that I can predict the single "correct" hypothesis. Never did, so don't strawman. I am pointing out that Occam's razor selects a single hypothesis as a tentative basis and in many cases the hypothesis is later falsified. It's entirely possible that there is a better basis for scientific development than this.
Yes, it's possible. Do you have any better suggestions than using the theory that combines being the simplest to use with being always correct as far as we know?


Originally Posted by stevea View Post
[...] So all data available to Newton would have equally supported both Newtown hypothesis and the Lorentz form and a million others. The only distinguishing feature is that Newton had no argument in favor of the "extra terms". Or obversely - Newton had no basis for rejecting the extra Lorentz terms. Why one is considered a greater presupposition than the other isn't well founded.
It really doesn't matter whether one is considered a greater presupposition than the other. What matters is that, if calculations of motion had been carried out using the full Lorentz form, enormous amounts of extra work would have been required, resulting in no benefit whatsoever. We are trying to reduce the complexity of tasks, not enhance it.

Originally Posted by stevea View Post
Perhaps we should consider a new scientific method that accepts (tentatively) ALL supported hypotheses, and only eliminates the falsified ones. This would leave the open questions open, rather than fill the gaps with simplistic presuppositions.
Perhaps, alternatively, we should carry on doing what we do at the moment, which is to take note of more complex hypotheses that explain phenomena correctly, to put them aside until their applicability can be determined in the light of new data, and in the meantime to use the simplest hypothesis that accurately predicts all the existing data. That way, we make our lives easier, rather than gratuitously, and potentially infinitely, more difficult, while retaining the potential benefit of more complex hypotheses as and when they're needed.

Dave
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