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Thought experiments

rivercanerivercane Veteran
edited June 2013 in General Banter
Anyone else enjoy thought experiments? From http://en.wikipedia.org/wiki/Thought_experiment:

A thought experiment or Gedankenexperiment (from German) considers some hypothesis, theory,[1] or principle for the purpose of thinking through its consequences. Given the structure of the experiment, it may or may not be possible to actually perform it, and, in the case that it is possible for it to be performed, there need be no intention of any kind to actually perform the experiment in question. The common goal of a thought experiment is to explore the potential consequences of the principle in question.

Famous examples of thought experiments include Schrödinger's cat, illustrating quantum indeterminacy through the manipulation of a perfectly sealed environment and a tiny bit of radioactive substance, and Maxwell's demon, which attempts to demonstrate the ability of a hypothetical finite being to violate the second law of thermodynamics.


I find that they can be a good bridge between the non-duality of Zen koans and the rationality and empiricism of science in that they can help the Western mind go beyond language. Many contain profound implications on the nature of consciousness. Here are a couple of my favorites.

Chinese room thought experiment

From http://en.wikipedia.org/wiki/Chinese_room:

If you can carry on an intelligent conversation with an unknown partner, does this imply your statements are understood?

Searle's thought experiment begins with this hypothetical premise: suppose that artificial intelligence research has succeeded in constructing a computer that behaves as if it understands Chinese. It takes Chinese characters as input and, by following the instructions of a computer program, produces other Chinese characters, which it presents as output. Suppose, says Searle, that this computer performs its task so convincingly that it comfortably passes the Turing test: it convinces a human Chinese speaker that the program is itself a live Chinese speaker. To all of the questions that the person asks, it makes appropriate responses, such that any Chinese speaker would be convinced that he or she is talking to another Chinese-speaking human being.

The question Searle wants to answer is this: does the machine literally "understand" Chinese? Or is it merely simulating the ability to understand Chinese?[6][b] Searle calls the first position "strong AI" and the latter "weak AI".[c]

Searle then supposes that he is in a closed room and has a book with an English version of the computer program, along with sufficient paper, pencils, erasers, and filing cabinets. Searle could receive Chinese characters through a slot in the door, process them according to the program's instructions, and produce Chinese characters as output. If the computer had passed the Turing test this way, it follows, says Searle, that he would do so as well, simply by running the program manually.

Searle asserts that there is no essential difference between the roles of the computer and himself in the experiment. Each simply follows a program, step-by-step, producing a behavior which is then interpreted as demonstrating intelligent conversation. However, Searle would not be able to understand the conversation. ("I don't speak a word of Chinese,"[9] he points out.) Therefore, he argues, it follows that the computer would not be able to understand the conversation either.

Searle argues that without "understanding" (or "intentionality"), we cannot describe what the machine is doing as "thinking" and since it does not think, it does not have a "mind" in anything like the normal sense of the word. Therefore he concludes that "strong AI" is false.


Mary's Room thought experiment

From http://www.philosophy-index.com/jackson/marys-room:

In philosophy of mind, Mary’s Room is a thought experiment meant to demonstrate the non-physical nature of mental states. It is an example meant to highlight the knowledge argument against physicalism.

The thought experiment is as follows: Mary lives her entire life in a room devoid of colour—she has never directly experienced colour in her entire life, though she is capable of it. Through black-and-white books and other media, she is educated on neuroscience to the point where she becomes an expert on the subject. Mary learns everything there is to know about the perception of colour in the brain, as well as the physical facts about how light works in order to create the different colour wavelengths. It can be said that Mary is aware of all physical facts about colour and colour perception.

After Mary’s studies on colour perception in the brain are complete, she exits the room and experiences, for the very first time, direct colour perception. She sees the colour red for the very first time, and learns something new about it — namely, what red looks like.

Jackson concluded that if physicalism is true, Mary ought to have gained total knowledge about colour perception by examining the physical world. But since there is something she learns when she leaves the room, then physicalism must be false. As Jackson explains:
It seems just obvious that she will learn something about the world and our visual experience of it. But then is it inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false.
personJeffrey

Comments

  • TheswingisyellowTheswingisyellow Trying to be open to existence Samsara Veteran
    I like Schrödinger's cat! I am partial to the idea in the sheer possibilities of any given situation until we pull it down and measure it (open the box). For me Schrödinger's cat represents the totality found in life, that any conceptual thing is what it is and at the same time everything it is not, like the cat, both simultaneously alive and dead. Upon our "measuring" we reduce these possibilities to that which we have measured, it doesn't tell us the what of a given thing, for having reduced it to this measurement or concept we have neglected the totality of the thing in question. The totality of a thing is reality, not a singular concept we have reduced it to.
    lobster
  • personperson Where is my mind? 'Merica! Veteran
    I'm a fan of these as well. I think it allows us into a world that we can't empirically observe.

    I was going to post Mary's room before I saw that you had already done so.
  • I like Schrödinger’s cat as well @Theswingisyellow! After all these years I still can't seem to fully get my head around it...really shows the power of the human mind and our ability to conceptualize something way before we have the means to conduct a scientific experiment. Kind of like Einstein and the Theory of Relativity.

    Yea, there's something about Mary's room @person. I mean, it seems obvious that she would gain knowledge by being able to see color for the first time, but according to Physicalism there should be no new knowledge to gain and we still can't quite define exactly what that is. Kind of like music or art.

    Good point @pegembara and very interesting post.

    Theswingisyellow
  • FlorianFlorian Veteran
    My problem with Mary the colour-scientist is that is that physicalism seems to be disproved by the existence of colour. So if Mary knows what 'green' looks like, or if anyone at all does, then physicalism must be false. No need for further complication.

    Is this not the case? Perhaps I'm missing something.
    person
  • Not sure I understand the question @Florian, but I think what supposedly disproves physicalsim is the fact that she should have had total knowledge of all colors, wavelengths, etc without ever seeing color.

    What is it that she has gained by seeing color? I think everyone would agree she has gained something, but what is it exactly? It seems to me it can't be defined and this mysterious something is what disproves purely materialist theory.
  • personperson Where is my mind? 'Merica! Veteran
    So there is this notion that you can keep dividing a length in half indefinitely so as to never reach the end, a thought experiment I suppose. However, in the real world when you get down to a Planck length ( 1.616199(97)×10−35 metres ), that is the smallest length that is possible so it can't be divided in half. Thus seemingly showing the initial thought experiment wrong. Don't ask me why a Planck length can't be divided in half though.

    I guess my point is that sometimes when the rubber hits the road, theory meets experiment, the world acts in strange and seemingly illogical ways.
  • JeffreyJeffrey Veteran
    I am now a planck length closer to understanding modern fizzicks. :p
    personlobster
  • lobsterlobster Veteran
    How amazing.
    I often leave a saucer of milk out for Schrödinger's cat/no cat. Only as a thoughtless experiment.

    Holding two or more complementary or conflicting ideas in the paradoxical world of our mind may not be presently possible. With practice and future AI symbiosis and some forms of spiritual practice we may improve our impossibilities at 'wider' thinking. We are not very bright compared to the potential of evolution.
  • FlorianFlorian Veteran
    rivercane said:

    Not sure I understand the question @Florian, but I think what supposedly disproves physicalsim is the fact that she should have had total knowledge of all colors, wavelengths, etc without ever seeing color.

    What is it that she has gained by seeing color? I think everyone would agree she has gained something, but what is it exactly? It seems to me it can't be defined and this mysterious something is what disproves purely materialist theory.

    My thought was that if she has a knowledge of colour, any colour, then physicalism is false. This is because colour depends on sentience. There's no colour apart from our perception of it. So if Mary is aware of the colour green then the case is made. No need for her to see red.

    Hence it seem to me that the thought experiment is taking a sledgehammer to crack a nut. Same for the second experiment, since we aleady know from the possibility of Behaviourism, the ufalsifiability of solpsism, etc. that there is no observed behaviour that could prove the existence of consciousness.

    So the thought experiments are very good and illustrate what they are suposed to illustrate, but they do not tell us anything we haven't know for centuries. Which is my objection to modern consciousness studies, that it has yet to say anything new and just goes around in circles. This is why I gave up my subscription to the journal of consciousness studies and started buying books on Buddhism.
    rivercane
  • FlorianFlorian Veteran
    edited June 2013
    person said:

    So there is this notion that you can keep dividing a length in half indefinitely so as to never reach the end, a thought experiment I suppose. However, in the real world when you get down to a Planck length ( 1.616199(97)×10−35 metres ), that is the smallest length that is possible so it can't be divided in half. Thus seemingly showing the initial thought experiment wrong. Don't ask me why a Planck length can't be divided in half though.

    I guess my point is that sometimes when the rubber hits the road, theory meets experiment, the world acts in strange and seemingly illogical ways.

    The Planck length is a limit on our calculations, not on Reality itself. If there really is a lower limit on the divisibility of space and time then Buddhist doctrine would have to be false. This was what Zeno was trying to tell us with his paradoxes, that space and time are not the way we usually think they are. Our usual idea of them is paradoxical. It is not the world that acts in paradoxical ways, it is our idea of the world. Nagarjuna proves that there are no true contradictions, therefore no paradoxes. Only if we think that spacetime is inherently or truly extended do we run into paradoxes. The root cause of all this is that existence itself is paradoxical, unless, that is, we assume that it is not an inherent property but some kind of illusion.

    Einstein's favourite mathematician (forget his name for now) saw the problem of reconciling the 'legato of the continuum' with the 'staccato' of a series of points as the most important in physics. But they cannot be reconciled. The whole idea of spacetime as physicists usually conceive of it is paradoxical. Buddhist ideas are a considerable advance on this, far more sophisticated and problem-free.




    riverflowpegembara
  • personperson Where is my mind? 'Merica! Veteran
    If there really is a lower limit on the divisibility of space and time then Buddhist doctrine would have to be false.
    @Florian I don't see the connection with Buddhist doctrine.

    Also, my rather limited understanding of the Planck length is that reality breaks down at anything smaller and so the Planck length is a limit on reality, it is only conceptually and mathematically that we can go smaller.

    My overall point is that sometimes our quite legitimate conceptual frameworks don't fit with the way the world seems to work. Maybe I'm just not understanding your argument.
  • cvaluecvalue Veteran
    Here is another experiment about thought of Dr. Masaru Emoto.

    "Emoto’s Water Experiment: The Power of Thoughts"

    http://www.highexistence.com/water-experiment/
  • JeffreyJeffrey Veteran
    Is planck's constant smaller than a 'string'?
  • ^^ Good question.
  • personperson Where is my mind? 'Merica! Veteran
    Apparently there is some dispute as to whether a Planck length is the smallest distance or not. If it is then space is quantized, meaning it is made up of discrete units.

    To copy one little snippet in favor of Planck length's absoluteness
    In some forms of quantum gravity, the Planck length is the length scale at which the structure of spacetime becomes dominated by quantum effects, and it would become impossible to determine the difference between two locations less than one Planck length apart. The precise effects of quantum gravity are unknown; often it is suggested that spacetime might have a discrete or foamy structure at Planck length scale.
    The other side seems to be saying that at present something at a Planck length is the smallest size that we could theoretically measure or see. Theoretically that is, the smallest thing we've measured at present is like 10x-16 and a Planck length is 10x-35
    So, the Planck length is the smallest size of any structure we will be able to see judging from the current state of knowledge. It doesn't mean that smaller structures don't exist - we will just not be able to see them in the conventional sense.
    @Jeffrey I'm not sure of the answer to your question. In the scale of the universe model they appear to be about the same size.

    http://www.scaleofuniverse.com/

    BTW, if you haven't seen this website check it out, its really cool.
  • FlorianFlorian Veteran
    person said:

    If there really is a lower limit on the divisibility of space and time then Buddhist doctrine would have to be false.
    @Florian I don't see the connection with Buddhist doctrine.

    Also, my rather limited understanding of the Planck length is that reality breaks down at anything smaller and so the Planck length is a limit on reality, it is only conceptually and mathematically that we can go smaller.

    My overall point is that sometimes our quite legitimate conceptual frameworks don't fit with the way the world seems to work. Maybe I'm just not understanding your argument.

    Hi @person. I think you'll find that conceptually and mathematically we cannot go smaller, and that this is why we sometimes treat a Planck length as being a real physical limit. But there is no evidence that spacetime is quantised and it is a blatantly paradoxical idea. On the other hand, the idea that spacetime is a true continuum and not quantised is also paradoxical (since a true continuum would have no parts and so could not be extended). Thus physics and metaphysics are unable to support one view of spacetime or the other. The only non-paradoxical idea is that there are two truths about space and time, and that extension is a conventional phenomenon and ultimately unreal. Physics has already come very close to this idea, and physicists occasionally conjecture that spacetime is an illusion of some sort.

    If our conceptual framework does not fit with the way the world works then it would not be legitimate, it would be incorrect. This is the connection with Buddhism, that if the Buddhist view is incorrect then spacetime is paradoxical. It would have to be conceived as being unambiguously quantised or unquantised, and both ideas fail in logic.

    I hope that makes sense. Feel free to object. I'm exploring these ideas, not speaking as an authority.







  • personperson Where is my mind? 'Merica! Veteran
    edited June 2013
    I've recently been on a cosmology kick. The philosophy of space being smooth vs quantized that you put forward is really interesting to me. Things in astronomy and physics are changing so fast these days its a really fun time to learn about these things. I came across this good video on new evidence for space being smooth. I think the bubble wrap in the analogy is quantized space at the Planck level, though I've still got a question about a gamma wave being able to be slowed down by rough space as even that is massively larger than the Planck scale, like the difference between an amoeba and the milky way, literally.

  • FlorianFlorian Veteran
    The trouble is that spacetime is not an issue for astronomy and metaphysics. Physics cannot address this question. It has to be resolved in logic (or in meditative practice), or not at all. Any theory for which spacetime is quantised or unquantised fails in metaphysics. If both types of theory did not fail there would be no problem. So it will be no use looking to the natural sciences to solve it. Better to look to Nagarjuna. His is the only solution that works. We just have to avoid the two extreme views.
  • FlorianFlorian Veteran
    Oh dear. That first sentence above should have read 'astronomy and physics'. Spacetime definitely is a matter for metaphysics.
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