An argument I often find myself drawn into with adherents of astrology, creationism, dualism or other such fairy tales is the definition of Science. I use the capital letter here because these arguments are about the over-arching structure of the scientific system rather than any one scientist's efforts or any one scientific theory.
To save myself some time, I'll post my argument here, once, so that I can simply point any bewildered netizens I encounter back to it and say, read this.
What is Science? First and foremost, it is an attempt to understand the world. That is not surprising, but even in this there is a buried statement. If you are making an attempt to understand the world, you are making the statement that the world can be understood, that it is not random or arbitrary. This is shared by all attempts at understanding, even primitive concepts like animism and misapprehensions like the Cargo Cults.
Science sets itself apart from other such attempts in that it constructs a system, a rigorous framework, in which we can build our understanding. The framework is based on metaphysical naturalism.
For Science does not permit of just any explanation. Science seeks to explain the world in terms of the world. For any event we observe, Science seeks an explanation in terms of other events we observe. Events that we cannot observe are precluded from our explanations.
So, for example, we observe that if we leave a piece of rotting meat lying about, after a few days we find it crawling with maggots.
Hypothesis: Maggots spontaneously form from meat if it is left undisturbed.
Hypothesis: Maggots are planted in the meat by invisible immaterial demons.
We have two plausible explanations, but they can't both be true. Why does this matter? Well, it matters because we want to know which explanation is the correct one. We can perform tests - experiments - to see if our Theory of Spontaneous Maggotation is true. We can put the meat in a tightly sealed jar and see if our maggots generate.
And, as it turns out, they do not.
We can repeat the experiment, and we find that while maggots appear in unprotected meat, meat in the sealed jar remains maggot-free. We can vary the experiment, and find that even if we do not seal the jar, but merely cover it with a cloth, there are still no maggots.
This means that the first hypothesis is incorrect. This hypothesis required only meat and time, which have both been provided, but with no maggots resulting.
What about our demons then? Well, they are invisible and immaterial, so they clearly would not be stopped by something as simple as a cloth. But a cloth does prevent maggots. What does this mean in demon terms? It means that we have observed intances where demons do not create maggots.
And that's all we can say.
The difference here is that we know the first explanation to be incorrect. We know it for certain. It is wrong. It is false.
The second explanation? Well, maybe sometimes the demons are busy inflicting cholera on the people of the next village. We don't know.
The difference is that the first is a natural explanation, and the second is a supernatural one. Natural explanations derive from natural causes, and we can control natural causes. Supernatural explanations derive from supernatural causes, and we cannot control those.
The meat is there. We gave it time. No maggots appear, so spontaneous generation is false.
The demons may or may not have been there. They are supernatural; we cannot preclude them; we may not even be able to detect their presence. We do not know, nor can we ever know, whether the demons are the cause or not.
The Theory of Spontaneous Maggotification is a scientific theory, and it is wrong. The Theory of Devilish Wormonising is not a scientific theory, because we can never know whether it is wrong.
Science's utility lies in its unique ability to throw out its trash. This is known as falsification, and although it has been acknowledged since the dawn of science, it was not until last century that Karl Popper fully explained its role.
For a hypothesis or a theory to be considered scientific, it must be falsifiable, that is, we must be able to determine if it is false. On the other hand, there is no requirement for a scientific theory to be provable, and indeed they are not. A scientific statement can be provable; the predictions made by theories are a good example of this.
Einstein's Theory of Relativity predicted that gravity would bend light in a certain way and by a certain amount. Observations by Sir Arthur Eddington confirmed this; the prediction was proved correct. This did not prove the Theory itself. It lent support to it, certainly, but that is all.
However, had it turned out that light was not bent by gravity, the Theory of Relativity would have been proved wrong, and discarded. It would have been falsified.
Now, back to our invisible demons. We know that if we cover the jar with a cloth, we don't get maggots. Is the cloth blocking the demons? That would make no sense, since the demons are supposed to be immaterial. Cloth or cork or wax stopper, all prevent the maggots, but none should present any barrier to our demons. (And we can note that wrapping people in cloth does little to prevent cholera.)
We can't say whether the demons are stopped by the cloth or just slacking, because we can't observe the demons. In fact, we have no direct evidence that the demons exist. We have postulated their presence from the existence of maggots, the corruption of wholesome meat. But now we have no maggots. Perhaps that flimsy layer of gauze really is an impassible barrier to maggot-demons.
Only... Now that we have no maggots, we have no reason to postulate the existence of demons at all. We haven't proved they're not there. The only sign we might have had of their presence is gone, but we said from the beginning that they were invisible.
And that's the problem with the Invisible Demon Theory. You can't ever know for sure that you're wrong.
But you can't prove that it's always correct. You can't test every situation, because there are infinitely many situations in which any theory might apply. A theory is supposed to tell you what to expect, so if all you ever do is test it, it's not much good.
You can't prove your theory, but what you can do is disprove it. We say, s = ut + ½at2 always. And we look for cases where it isn't. We can't ever hope to prove it true, but just one counter-example will prove it false. And if, over time, we find no such examples, we gain confidence in the theory. We would gain confidence too from a mass of confirming evidence, but there is a critical difference: In one case, we were trying to prove it right, and we didn't happen to stumble across anything to the contrary. In the other, we were actively seeking counter-examples, and despite our best efforts we couldn't find any.
Failure of falsification can offer much stronger support than mere confirming evidence.
So falsifiability inevitably arises as a key requirement if you wish to construct a rigorous system for explaining the world. You have to test your ideas, and this is the only reliable way to do so.
But falsification is impossible for theories deriving from the supernatural. Which means that any rigorous system for explaining the world must be naturalistic. It must preclude all supernatural causes, and forbear trying to explain supernatural events, because the former cannot produce useful explanations and the latter... cannot even be detected.
So Science, from humble beginnings as simply a concerted attempt to get the right answer, turns out to necessarily require both metaphysical naturalism as its foundation and falsification as its primary tool in seeking truth. And it is unique. There is only one Science. A system based on naturalism and using falsification to test ideas is Science. A system that fails of either of these is not.
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I get all tingly when you write things like this...;)
Posted by: Susie at Saturday, November 12 2005 09:11 AM (a0oF7)
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Good to know I haven't lost my touch. :)
Posted by: Pixy Misa at Saturday, November 12 2005 10:02 AM (QriEg)
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The way to find out if a theory is falsifiable is for it to tell us what
can't happen.
All falsifiable theories can make predictions of this form: It is impossible for us to ever see xxxxx. (Where xxxxx is something we can think of a way to look for.)
The demon theory of maggots can make no such prediction.
Posted by: Steven Den Beste at Saturday, November 12 2005 01:45 PM (CJBEv)
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Yes. I'd like to tighten up the article, but it was after midnight and I decided to just post the darn thing. I'll come back and edit it some more when I'm done moving 200 web sites to our new servers.
Posted by: Pixy Misa at Saturday, November 12 2005 05:08 PM (QriEg)
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Excellent!
And you even avoided mentioning the misleading "Scientific Method" so dear to the hearts of grade school teachers.
I'd just add one thing: the thing that Feynman stressed in his Caltech commencement address Cargo Cult Science.
Science is based on honesty: absolutely witheringly brutal bend-over-backwards honesty, including brutal self-honesty.
I work with scientists daily, and interact with plenty on lists and newsgroups, and I've met a few who are NOT honest. Scientists are human, so the human habit of dishonesty cannot be ignored. The presence of dishonest scientists shows that it's critically important for us to always stress how large a role that honesty plays.
I might even put honesty above "an attempt to understand the world." There are many different attempts to understand the world (religion among them,) but what separates Science from all the rest is its incorporation of extreme backbreaking honesty. Science without honesty will turn into politics or religion. And I suspect that if religion adopted brutal honesty in all of its acts, then religion would quickly turn into science.
Posted by: Bill Beaty at Saturday, November 12 2005 05:46 PM (/7z+c)
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Up until here you were excellent:But falsification is impossible for theories deriving from the supernatural.
The problem with the "maggot-planting demons" theory is not that the demons are supernatural. The problem is that the demons don't do anything we can observe, apart from putting maggots into meat. It's the absence of visible
effects that sinks the theory, not the appeal to invisible causes.
Consider the postulate, made in the 19th century, of a luminiferous ether as the medium for waves of light. The ether was not observable itself (because it doesn't actually exist) but scientists believed in it, because they could predict events correctly by assuming it was there. It was when Michelson and Morley tried to measure the Earth's motion with respect to the ether, and got the "impossible" result that the Earth wasn't moving at all, that scientists lost confidence in the ether's existence. The impossibility of observing the ether gave scientists no difficulty; it needed a failed experiment to raise doubts.
The essential part of doing science is to follow out a theory's logical consequences until one reaches an assertion about observable events, and then test that assertion against reality. That is "falsification". But a scientific theory can perfectly well include unobservable causes, provided that everywhere it predicts observable events, those events come to pass -- as with the luminiferous ether. (The spacetime 4-manifold of relativity, and the virtual particles of quantum field theory, are unobservable themselves also; no one denies their existence on that account.) So naturalism, being a limit on the causes one may suggest, is far from necessary to science; and might well prove an impediment to it, by stifling imagination.
A final point. If science were based on naturalism, as you suppose, it would not be evidence for naturalism. There are people who will disbelieve their own eyes rather than admit a favorite theory of theirs is wrong, but they aren't called as witnesses to their theory. It is only if scientists are prepared, given good evidence, to entertain supernatural causes, that their testimony against such causes, when evidence is absent, carries weight.
Posted by: Michael Brazier at Saturday, November 12 2005 08:36 PM (8LTnv)
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The luminiferous ether (if it existed), space-time, and virtual particles can all be observed - by interaction. All natural observations are by interaction, so this is no distinction from anything else. So they are natural.
Invisible immaterial demons cannot be observed by interaction, by their very definition. That's what makes them supernatural.
So as I said, Science requires metaphysical naturalism, and you remain, as always, wrong.
If science were based on naturalism, as you suppose, it would not be evidence for naturalism.
It is the former, and since it works, it is the latter as well. If it didn't work, it would be evidence
against naturalism.
There are people who will disbelieve their own eyes rather than admit a favorite theory of theirs is wrong, but they aren't called as witnesses to their theory.
Which has nothing to do with anything we are discussing.
It is only if scientists are prepared, given good evidence, to entertain supernatural causes, that their testimony against such causes, when evidence is absent, carries weight.
Supernatural causes cannot be coherently entertained in any rigorous system of explanation of the world. If there are supernatural causes, a rigorous system of explanation is impossible.
Posted by: Pixy Misa at Saturday, November 12 2005 08:52 PM (QriEg)
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The problem is that the demons don't do anything we can observe, apart from putting maggots into meat.
That's what supernatural means!
If they had consistent and observable properties, that is, if they interacted with the Universe in a consistent and observable way, they wouldn't be supernatural. They also wouldn't be invisible immaterial demons.
The supernatural, by definition, interacts with the natural
inconsistently. That dynamites any chance of falsification.
You're still wrong, but I have to thank you for bringing up cogent points that I need to clarify.
Posted by: Pixy Misa at Saturday, November 12 2005 08:56 PM (QriEg)
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And I'll also note that dualism is the most fundamentally inconsistent metaphysical concept ever created. Science is utterly impossible under a framework of dualism.
Posted by: Pixy Misa at Saturday, November 12 2005 08:58 PM (QriEg)
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The luminiferous ether (if it existed), space-time, and virtual particles can all be observed - by interaction. All natural observations are by interaction, so this is no distinction from anything else. So they are natural. Invisible immaterial demons cannot be observed by interaction, by their very definition.
Well, no; as you described the theory, these immaterial demons interact with meat, which can be observed. So that doesn't capture the objection to theories like this. You seem to have realized this:
If they had consistent and observable properties, that is, if they interacted with the Universe in a consistent and observable way, they wouldn't be supernatural. They also wouldn't be invisible immaterial demons.
Unfortunately that doesn't capture the objection either; the demons' behavior, as far as we can observe them, is perfectly consistent, in that we can predict what they will do.
The real objection is, as I said before, that no inference can be reached from what the demons do to meat to anything else they might be expected to do. The theory yields no testable predictions, except for the one type of events it was built to explain; that is why it isn't scientific. But the supernatural aspect of the theory has nothing to do with that failure. A theory that maggots are generated in meat by interaction with a weightless, odorless gas named frammistine, which is inert to every substance except meat, would be non-scientific for the same reason.
On "science is based on naturalism": let's imagine a haystack, and two men who are asked whether there's a needle buried in the haystack. The first man answers, "A haystack, by definition, is made out of hay, not of needles; therefore I am certain there are no needles in this haystack." The second man says, "I have examined most of the hay in this haystack, and haven't found a needle; therefore I believe the part I haven't examined is not likely to have a needle in it." Which man would you call for to prove the absence of a needle: the first, or the second?
If science presupposes naturalism, it's parallel to the first man. If science is free to consider the supernatural, but hasn't found any compelling evidence of it, it's parallel to the second man. Science is far more convincing an advocate for naturalism if it reaches that position as a conclusion, than if it starts from there as a premise ...
Science is utterly impossible under a framework of dualism.
You mean, naturalism is impossible under a framework of dualism -- quite true, but not worth saying. But what you said is quite peculiar. One small miracle, however distant it may be from us in time or space, would undermine all our science and prove the cosmos to be irrational and incomprehensible? If we admit one ghost into the world, the laws of physics are a mere comforting delusion? Is it really true that unless all we survey fits into the same pattern, there is no pattern at all?
Posted by: Michael Brazier at Sunday, November 13 2005 05:01 AM (hc1pe)
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Daaaaaaa-urrrrr... *scratching head*...
I like pie.
Y'know, I'm not a dumb person at all... at least, I don't
think I am... but there are times that I get into reading stuff like this and you can just HEAR my brain cells giving up in droves.
Posted by: Wonderduck at Tuesday, November 15 2005 12:27 AM (HoSBk)
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Wonderduckling, the sound you hear is not surrender, but
growth.
;-)
Posted by: matoko-chan at Tuesday, November 15 2005 02:29 AM (cxYaY)
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Michael, sorry, I've been busy and unable to correct your delusions these last few days.
One small miracle, however distant it may be from us in time or space, would undermine all our science and prove the cosmos to be irrational and incomprehensible?
Yes.
If we admit one ghost into the world, the laws of physics are a mere comforting delusion?
Yes.
Is it really true that unless all we survey fits into the same pattern, there is no pattern at all?
Yes.
Let's take a quick look at what Dualism says, okay?There are two realms of existence: Matter, the physical world; and Mind, the world of subjective experience. They are entirely separate and apart, and do not interact in any way... Except when they
do.In this fundamental internal inconsistency Dualism embraces the supernatural. That makes falsification impossible, because there is no requirement for
anything to be consistent anymore. And that makes Science impossible.
Michael, Naturalism is impossible under Dualism, and Science requires Naturalism, absolutely and indisputably. Dualism is an inane happy-land bywater of philosophy that is entirely useless for any sort of rational thought. I'll leave you to it.
Posted by: Pixy Misa at Saturday, November 19 2005 01:42 PM (3FPsg)
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Oh, and although I consider Idealism to be bunk,
some forms of Idealism
can support Naturalism. Of course, they are then intrinsically indistinguishable from Materialism, but them's the lumps.
Posted by: Pixy Misa at Saturday, November 19 2005 01:45 PM (3FPsg)
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Very nice, Pixy. Very nice, indeed.
Posted by: Neal at Saturday, November 19 2005 07:42 PM (pdiJG)
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Let's take a quick look at what Dualism says, okay? "There are two realms of existence: Matter, the physical world; and Mind, the world of subjective experience. They are entirely separate and apart, and do not interact in any way... Except when they do." In this fundamental internal inconsistency Dualism embraces the supernatural. That makes falsification impossible, because there is no requirement for anything to be consistent anymore. And that makes Science impossible.
First: If that's what "Dualism" means, I'm not a Dualist. I do believe that Mind is more than Matter, but not that Mind's relations with Matter are lawless.
Second: Quantum mechanics, one of science's great triumphs, actually is Dualist as you define it. Systems of quantum particles and "measuring devices" belong to different classes of existence, and while the theory says precisely what happens when they interact, it does not even try to predict where and when interactions occur. Measurements, it would appear, are lawless intrusions into an otherwise determinate world of matter. Going by your definitions, then, quantum mechanics admits the supernatural and thus cannot be Science ...
You are no doubt ready to say "Oh, that just shows you don't understand quantum mechanics!" Please don't. This is exactly the view real working physicists take of quantum mechanics. The attempt to find a law for "measurements" that fits the observed facts is a prominent open problem in physics and a subject of current research. My point is, since quantum mechanics flatly contradicts Naturalism, it can hardly be said to presuppose it, and yet it makes a host of testable predictions, all of which have proved correct; so either one of the most useful theories ever conceived is not science, or science can dispense with Naturalism.
Posted by: Michael Brazier at Monday, November 21 2005 05:08 PM (8LTnv)
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I do believe that Mind is more than Matter, but not that Mind's relations with Matter are lawless.
Which means what? Is Matter a subset of Mind? Is Mind bound by the same physical laws as Matter? What?
Quantum mechanics, one of science's great triumphs, actually is Dualist as you define it.
No it isn't.
Systems of quantum particles and "measuring devices" belong to different classes of existence, and while the theory says precisely what happens when they interact, it does not even try to predict where and when interactions occur.
That is completely wrong in every respect.
Every respect.
Measuring devices
are systems of quantum particles. The theory
does predict when and where interactions occur.
You don't understand Quantum Mechanics. Or, it appears, Naturalism, Dualism, or Logic.
Posted by: Pixy Misa at Monday, November 21 2005 07:06 PM (3FPsg)
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Michael, further to my previous comment:
If you have a system of Matter, that follows a consistent set of laws, and a system of Mind, that follows its own consistent set of laws, and the interactions between Matter and Mind are
also governed by a consistent set of laws, it follows that you can replace the two domains and three sets of laws with a single domain of
Stuff and a single set of laws.
In other words, any internally consistent form of Dualism is in fact Naturalism. It is only Dualism if it is inconsistent, and that inconsistency makes Dualism worthless even as a philosophical concept.
Posted by: Pixy Misa at Monday, November 21 2005 07:47 PM (7X4Bl)
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This is a wonderful post. Cogently and clearly points out the importance of naturalism in science and the absurdity of those who claim that science must accomodate the supernatural.
Posted by: Tanooki Joe at Tuesday, November 22 2005 12:18 AM (loZG3)
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Pixy, search for "Wigner's friend" on Google, read some of the pages you'll get, and then try to tell me "measurement" is well-defined in quantum mechanics.
Measuring devices are systems of quantum particles.
Don't confuse reality with the model of it. Anything we call a "measuring device" is, in fact, a collection of elementary particles -- but, to make any use of quantum mechanics, we pretend our measuring devices are not controlled by quantum mechanics. If we didn't do that, the theory would make no predictions at all. Every interpretation of quantum mechanics is Dualist, because you have to split the universe into the measuring and the measured just to get started.
If you don't believe me, look up Lee Smolin -- who has said:I am convinced that quantum mechanics is not a final theory. I believe this because I have never encountered an interpretation of the present formulation of quantum mechanics that makes sense to me. I have studied most of them in depth and thought hard about them, and in the end I still can't make real sense of quantum theory as it stands.
Posted by: Michael Brazier at Tuesday, November 22 2005 03:14 AM (hc1pe)
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to make any use of quantum mechanics, we pretend our measuring devices are not controlled by quantum mechanics. If we didn't do that, the theory would make no predictions at all.
Eh? QM
theory makes predictions of the interactions between quantum paticles. It doesn't give a fig for measuring devices.
If you don't believe me, look up Lee Smolin -- who has said: [snip]
Michael, do you know the difference between interpretations of QM and QM itself? Because that's what Smolin is talking about. The Copenhagen Interpretation, the Many Worlds Interpretation, Transactional models and so on. Smolin finds them lacking; so do some other very reputable physicists; and other very reputable physicists disagree.
But the Interpretation is not the Theory, and is in fact
entirely irrelevant to the Theory. You do not need
any interpretation to successfully apply QM to a problem.
So your claim of Dualism in this case is, depending on how you wish to look at it, either completely wrong or entirely beside the point. You choose.
Posted by: Pixy Misa at Tuesday, November 22 2005 03:48 AM (AIaDY)
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I looked up Wigner's Friend as you suggested.
As I said, you're confusing the interpretations with the theory itself. Tut tut.
Posted by: Pixy Misa at Tuesday, November 22 2005 03:52 AM (AIaDY)
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And so was Wigner.
However, a conscious observer (according to his reasoning) must be in either one state or the other, hence conscious observations are different, hence consciousness is not material.
Wigner had absolutely no basis for claiming that consciousness cannot be in a superposition of states. There is
nothing in the mathematics of QM that suggests anything of the sort. Sorry, but even as a thought experiment this is complete bunk.
Posted by: Pixy Misa at Tuesday, November 22 2005 03:57 AM (AIaDY)
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What's more, if the mind is magical and not subject to the laws of Quantum Mechanics, and yet is able to interact with QM systems, you arrive unavoidably at the same sort of inconsistency that afflicts all forms of Dualism, and Science becomes impossible.
I really don't think Wigner thought it through.
Posted by: Pixy Misa at Tuesday, November 22 2005 04:03 AM (AIaDY)
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I couldn't get back to this before now, sorry...
Let's deal with a concrete example of QM in action, the classic two-slit interference effect. We have a source of photons, a sensitive photographic film, and a screen with two pinholes placed between them. If we pose the question "What is the probability that a photon from the source will hit a given spot on the film?" QM gives an answer which (if we turn on the source and observe events) proves to be correct. But by posing that question we are implicitly assuming that, when a photon interacts with the film, it must hit one and only one spot on the film. And, if we take the film to be a system of quantum particles described wholly by Schrodinger's equation, that assumption isn't justified. For the photons in question, at the moment they interact with the film, are in a superposition of states; and when a quantum system in a superposition of states interacts with another quantum system, the result is not to reduce the first system to one of its constituents, but to put the other system into superposition.
The question "What is the probability that a photon from the source will hit a given spot on the film?", thus assumes that the film is not fully described by Schrodinger's equation. The problem with QM, as a conceptual scheme, is that there's nothing in the theory itself which says when, or even whether, you are allowed to make assumptions of that kind. That's what the interpretations are for: they fill a gap in the scheme. (Notice that there were never any "interpretations" for the equations of Newton, Maxwell, or Einstein. Their theories didn't have conceptual gaps to fill before they could be applied to reality.)
Wigner had absolutely no basis for claiming that consciousness cannot be in a superposition of states. There is nothing in the mathematics of QM that suggests anything of the sort.
Nothing in the mathematics, to be sure; but the mathematics of QM are not -- don't even claim to be -- a complete description of reality. The point of "Wigner's friend" is to bring out just where the mathematics falls short.
What's more, if the mind is magical and not subject to the laws of Quantum Mechanics, and yet is able to interact with QM systems, you arrive unavoidably at the same sort of inconsistency that afflicts all forms of Dualism
Yes. That's what I meant by saying that QM is Dualist. To justify posing the questions that QM answers, you have to appeal to something that isn't subject to the rules of QM, and the actions of that something are not predictable. And that's also what Smolin meant by saying that QM is not a "final theory". A final theory would characterize the something, in addition to quantum particles.
Which brings us back to the original point. QM implies the existence of a class of being which it does not even attempt to describe, or to predict the behavior of, in order to explain the behavior of the entities it does describe. (The interpretations of QM are attempts to describe this other class of being.) Therefore it implies the falsity of Naturalism. And therefore QM cannot possibly presuppose Naturalism. If science must presuppose Naturalism, as you maintain, QM is not science -- even though it has been tested against reality in a host of ways, and has never been falsified yet.
Posted by: Michael Brazier at Monday, November 28 2005 06:19 PM (8LTnv)
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About the "inconsistency" of Dualism: you are actually asserting, not that Dualism asserts a contradiction (which is what "inconsistent" means in my lexicon) but that Dualism makes no predictions that could be tested against observed events. "It's not right -- it's not even wrong", in short. Well, there's QM again, which a) is implicitly Dualist and b) makes many testable predictions ... Never mind whether QM is correct -- its very existence puts your philosophy in question.
Posted by: Michael Brazier at Monday, November 28 2005 06:41 PM (8LTnv)
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I couldn't get back to this before now, sorry...
Not a problem.
But by posing that question we are implicitly assuming that, when a photon interacts with the film, it must hit one and only one spot on the film.
That depends on how you choose to interpret the question. If you interpret it in terms of Quantum Mechanical
theory, the question either implies nothing of the sort, or if you are strict in your interpretation, is not a valid question of QM.
For the photons in question, at the moment they interact with the film, are in a superposition of states; and when a quantum system in a superposition of states interacts with another quantum system, the result is not to reduce the first system to one of its constituents, but to put the other system into superposition.
Sure.
The question "What is the probability that a photon from the source will hit a given spot on the film?", thus assumes that the film is not fully described by Schrodinger's equation.
Depends on the interpretation.
Remember, QM is described by
mathematics, not by the English language. Actual questions in QM are also formulated mathematically. The confusion only arises because you are posing your questions in English, which is inherently sloppy.
Wigner had absolutely no basis for claiming that consciousness cannot be in a superposition of states. There is nothing in the mathematics of QM that suggests anything of the sort.Nothing in the mathematics, to be sure; but the mathematics of QM are not -- don't even claim to be -- a complete description of reality.I realise that.The point of "Wigner's friend" is to bring out just where the mathematics falls short.Except that Wigner's friend is based on an unfounded assumption, and does not address the mathematics of QM in any way - only the
interpretation of QM.What's more, if the mind is magical and not subject to the laws of Quantum Mechanics, and yet is able to interact with QM systems, you arrive unavoidably at the same sort of inconsistency that afflicts all forms of DualismYes. That's what I meant by saying that QM is Dualist.Except that Wigner's friend does not address QM at all, only certain interpretations of QM, and specifically,
Wigner's interpretation. Which is clearly not internally consistent (by his own argument) and can be safely ignored. To justify posing the questions that QM answers, you have to appeal to something that isn't subject to the rules of QM, and the actions of that something are not predictable.No.A final theory would characterize the something, in addition to quantum particles.QM makes no assumptions of any such
something. Sorry, you are completely wrong.QM implies the existence of a class of being which it does not even attempt to describe, or to predict the behavior of, in order to explain the behavior of the entities it does describe. No. It does nothing of the sort.The interpretations of QM are attempts to describe this other class of being.Some
interpretations of QM - notably Wigner's - fall into this trap. QM itself does not. QM is a mathematical description of nature. It starts and ends with naturalism.
Posted by: Pixy Misa at Monday, November 28 2005 08:09 PM (AIaDY)
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About the "inconsistency" of Dualism: you are actually asserting, not that Dualism asserts a contradiction (which is what "inconsistent" means in my lexicon) but that Dualism makes no predictions that could be tested against observed events.I am asserting nothing of the sort.
I am asserting that Dualism is inherently inconsistent.
As I said, Dualism asserts two spheres of existence, which do and don't interact.
If they interact consistently, they can be described more simply as a single sphere of existence, and it becomes Naturalism.
If they do not interact, then the statement is meaningless.
Only if the interaction is inconsistent is it Dualism.
As it is normally stated, Dualism is self-contradictory, but it is possible to state it such that it merely requires the
Universe to be inconsistent.Well, there's QM again, which a) is implicitly Dualist and b) makes many testable predictions ... Never mind whether QM is correct -- its very existence puts your philosophy in question.Except that you are persistently misrepresenting what QM actually says. There is no Dualism implied by QM. None whatsoever. Only the material.
Wigner tried to produce Dualism out of QM and immediately mired himself in contradiction, showing both that QM is
not Dualist in nature and Dualism is inherently inconsistent.
Posted by: Pixy Misa at Monday, November 28 2005 08:17 PM (AIaDY)
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Remember, QM is described by mathematics, not by the English language. Actual questions in QM are also formulated mathematically. The confusion only arises because you are posing your questions in English, which is inherently sloppy.
Not so; I understand the mathematics involved, and the mathematical formalism of QM is Dualist. Take the photographic film and the photon. The position of the photon, when it reaches the film, is given in QM by a function from points on the film to "amplitudes", which are complex numbers; and the state of the film after the photon reaches it is, exactly, that function. Discovering this function from the state of "photon at light source" (also a function from positions to amplitudes) involves very advanced mathematics, but it poses no conceptual problems. Call this process "state evolution."
However, having that state does not answer the question "what is the probability of the photon reaching point A on the film?" To do that you take the norm of the amplitude at point A, which is a much simpler procedure in technical terms. But -- note this, please -- that step isn't described by the equations which describe the change from the "photon at source" state to the "photon at film" state! This step, state reduction, bears no resemblance to state evolution, except that both change the current state from one function to another. Moreover, the formalism does not specify when you are supposed to use state reduction, rather than state evolution.
That's the Dualism in QM: two different dynamical laws, exactly one of which applies at any given moment, and no rule saying when to use one or the other. All the interpretations of QM are Dualist because they exist to specify when state reduction is the right law.
The one apparent exception among them, the many-worlds interpretation, turns out to conceal a Dualist premise: for what it says is that state reduction never happens, and our belief that it does is an artifact of our perceptions. The problem is that on that account, as perception is a product of state evolution like all other events, it cannot distinguish pure states from superpositions. (Only state reduction can do that.) This means we should, sometimes, perceive a superposition directly -- a thing which never happens. To explain why this doesn't happen, you have to introduce a theory of perception, which brings the mind/matter version of Dualism back into science.
As I said, Dualism asserts two spheres of existence, which do and don't interact. If they interact consistently, they can be described more simply as a single sphere of existence, and it becomes Naturalism. If they do not interact, then the statement is meaningless. Only if the interaction is inconsistent is it Dualism.
Here you want "consistent" to mean predictable...
... showing both that QM is not Dualist in nature and Dualism is inherently inconsistent.
... and here you want it to mean not contradictory instead. Sorry, those are not the same thing. There are, for instance, sets of natural numbers with definitions quite free of contradiction, but whose members can't be predicted. If I remember the jargon from the theory of computation, these are the "recursively enumerable" sets. It's true that Dualism postulates a partly unpredictable universe, but the jump from "unpredictable" to "contradictory" is not justified by logic or observation.
Oh, and you're a bit confused about Wigner. Certainly he was arguing for a specific interpretation of QM, in which state reduction is caused by an interaction of mind with matter. But "Wigner's friend" is a sharpening of "Schrodinger's cat", which points out the implausibility of state evolution (as QM describes it) at macroscopic scales. The difficulty it raises is inherent to QM, and isn't confined to Wigner's favorite interpretation.
Posted by: Michael Brazier at Tuesday, November 29 2005 12:18 AM (8LTnv)
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However, having that state does not answer the question "what is the probability of the photon reaching point A on the film?"As I said, it depends on how you interpret that question. QM is mathematics, and that question is English, so you
have to interpret it.That's the Dualism in QM: two different dynamical laws, exactly one of which applies at any given moment, and no rule saying when to use one or the other.Nonsense. Under QM, everything follows QM. There's nothing else.But -- note this, please -- that step isn't described by the equations which describe the change from the "photon at source" state to the "photon at film" state!Because it's not part of QM. It's an interpretation of the question, which
was not phrased in terms of QM.All the interpretations of QM are Dualist because they exist to specify when state reduction is the right law.That's an interesting assertion - but it has no bearing on QM
as a theory, only on whether the interpretations are of scientific value. And in fact it is wrong, as it is always possible to assume that state reduction does not happen. And indeed:The one apparent exception among them, the many-worlds interpretation, turns out to conceal a Dualist premise: for what it says is that state reduction never happens, and our belief that it does is an artifact of our perceptions. The problem is that on that account, as perception is a product of state evolution like all other events, it cannot distinguish pure states from superpositions.Rather, it means that there are no "pure states".(Only state reduction can do that.) This means we should, sometimes, perceive a superposition directlyThat is a complete non-sequitur.
All you have is superpositions of states interacting with other superpositions of states, ad infinitum. There is no reason whatsoever to assume that we would experience that directly, because
experience itself is a superposition of states.To explain why this doesn't happen, you have to introduce a theory of perception, which brings the mind/matter version of Dualism back into science.That objection is at least understandable. How does linear subjective experience arise from the infinite paralleism of MWI? Easy: MWI is no different mathematically from QM. It is merely an interpretation. The predictions are
identical to those of any other interpretation. The predictions of QM are perectly consistent with a biochemical brain generating a consciousness that has a single stream of experience (which is not quite how we actually experience the world, but anyway). The fact that under this interpretation wave functions never collapse
makes no difference. The mathematics works out the same regardless.Here you want "consistent" to mean predictable...Okay, here's the deal.
The concept of Dualism can be phrased in two ways. In one, the concept is inherently self-contradictory. In the other, the Universe is defined to be inconsistent.
Let's walk through it.
Dualism means there are two modes of existence.
If they interact in a consistent manner, there
aren't two modes of existence, and Dualism has contradicted itself.
If they don't interact at all, there aren't two modes of existence, and Dualism has contradicted itself.
Only if they interact inconsistently can Dualism even be a coherent philosphy. Because any rule binding the two existences proves the principle of Dualism to be false. Any rule at all. Dualism requires that the Universe act inconsistently, and therefore not be subject to Science - at all.The difficulty it raises is inherent to QM, and isn't confined to Wigner's favorite interpretation.No. As always, you are confusing interpretations with the theory itself.
Schroedinger's Cat held a useful lesson about QM: It teaches us that our preconceptions about how the world works do not apply to the quantum world.
Wigner's Friend however only teaches us that Wigner failed to understand Schroedinger's lesson. Wigner is mired in his preconceptions on the nature of consciousnss, granting it a special state when he had no scientific basis for this.
And you, Michael, are falling into the exact same trap. You claim that QM is dualistic because you have your notion of how the Universe works, and you have QM, and they are incompatible. The problem is, this doesn't mean that QM is dualistic; it simply means that
you are wrong. Your notions of the way things are, to which you ascribe the status of Reality, are in fact merely a stochastic model of QM processes. It's all QM; you, me, this conversation, Wigner and his friend, all of it described by the one set of equations. There is no more, and no more is needed.
(Well, until we bring gravity into it, anyway...)
Posted by: Pixy Misa at Tuesday, November 29 2005 07:15 AM (QriEg)
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The one apparent exception among them, the many-worlds interpretation, turns out to conceal a Dualist premise: for what it says is that state reduction never happens, and our belief that it does is an artifact of our perceptions. The problem is that on that account, as perception is a product of state evolution like all other events, it cannot distinguish pure states from superpositions.
Rather, it means that there are no "pure states".
Well, technically the "pure" states in which a particle is 100% certain to be at one point are not physical. But states in which a particle is known to be less than a small distance away from one point with less than a small probability of error
are physical. The point is that state reduction tends to produce states of that kind, while state evolution does not.
All you have is superpositions of states interacting with other superpositions of states, ad infinitum. There is no reason whatsoever to assume that we would experience that directly, because experience itself is a superposition of states.
This calls for a deeper exploration of the math. Quantum states occupy a space of functions (called Hilbert space) which is a vector space, and the nearly-pure states form a basis for that space. As far as state evolution is concerned, there isn't anything special about that basis. Any set of states that spans Hilbert space contains just as good a basis, even a set whose members are all intricately mixed superpositions.
Observations, however, show that the basis of nearly-pure states is preferred by real particles. The many-worlds interpretation says this is an artifact of our mode of perception. What we perceive is a projection of the universe's true state into a subspace of the Hilbert space to which it belongs. But the fact that we perceive only along a subspace itself needs explanation. State evolution takes no account of subspaces or projections into them; if perception takes them into account, it cannot be a result of state evolution.
Put differently, if we the observers are only a quantum system, fully predictable by state evolution, then we should perceive the state of the rest of the universe as a whole. Our perceptions could not decompose that state into multiples of states in some basis, because the states in a basis don't physically exist. Decomposition of a state vector requires more information on the structure of Hilbert space than state evolution provides. To account for the fact that we perceive, not the whole state of the universe, but a component of it, we must invoke something outside the universe to provide the extra information.
The question which interpretations exist to answer is, why does observation of quantum systems invariably show those systems in nearly-pure states, and never shows them in superpositions? Or in more formal language: why are quantum systems always observed in states that are multiples of members of a particular basis, and never in linear combinations of these? The many-worlds interpretation "answers" it by transferring it out of the material realm and into a realm of subjective perceptions -- which is not, really, an answer at all. Indeed, not only does it appeal to an immaterial class of being (which makes it Dualist), it does so in a way that precludes any inquiry into that class. Your silly "maggot demon" theory gives more scope for investigation ...
On to the walk-through of Dualism:
If they interact in a consistent manner, there aren't two modes of existence, and Dualism has contradicted itself.
Substitute "fully predictable" for "consistent", and I agree to this.
Only if they interact inconsistently can Dualism even be a coherent philosphy. Because any rule binding the two existences proves the principle of Dualism to be false. Any rule at all.
Again I substitute "fully predictable" for "consistent" ... and the argument fails. Where is the contradiction in assuming a rule that specifies effects up to a point, but not in full? That's what state reduction does in QM: "Repeat this experiment many times, and the results follow this probability distribution."
The fact is, you won't accept any description of reality unless it's both comprehensive and deterministic. That drives you to the many-worlds interpretation of QM, because every other attempt to make sense of QM is not deterministic. But many-worlds isn't comprehensive, and can't be extended in any testable way to make it so. Which means it fails the falsifiability criterion. Insisting on absolute predictability is driving you away from interpretations that are open to refutation, and to one that both provokes further inquiry and denies the possibility of any results from such inquiry.
Posted by: Michael Brazier at Tuesday, November 29 2005 06:52 PM (8LTnv)
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The debate on defining science is something that amazes me intellectually.
My scientific level of knowledge doesn't allow me to bring any argument about it but it makes me have some questions.
In regard of the Godel's Theorem, doesn't the pricnciple of Falsifiability lead to the conclusion that mathematics itself is not science? Therefore, considering that every matter known as scientific is not science as well because all of them use the results of mathematics ???
I'm puzzled.
Posted by: L_Raj at Monday, December 05 2005 10:47 PM (dahsf)
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In regard of the Godel's Theorem, doesn't the pricnciple of
Falsifiability lead to the conclusion that mathematics itself is not
science?Well, you don't really need Godel's Theorem for this. Mathematics is not science in any case. Mathematics is mathematics.
Posted by: Pixy Misa at Friday, August 18 2006 04:22 AM (FRalS)
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