Metaphysics and Effective Theories

I’ve lately been finding it really difficult to get myself interested in alleged metaphysical issues stemming from assuming that a certain physical theory applies to the entire universe. Many of the ‘philosophical’ problems of quantum mechanics, for example, are of this ilk, as are many in algebraic quantum field theory and general relativity.

The standard practice in philosophy of physics is to use a so-called fundamental theory for your metaphysical inferences. Effective theories are for the most part ignored. The intuition is that the ‘fundamental theory’ describes ‘what is really out there’ while effective theories are somehow more phenomenological, or derivative of the fundamental theory (and hence need not be considered in addition to the fundamental theory).

A question arose in class today as to why is it that people who worry about entanglement in quantum mechanics typically worry about it in relation to special relativity rather than general relativity. The standard answer is that gravity is an effect that is negligible in the entanglement experiments we are considering, so we do not have to worry about what a quantum theory of gravity would have to say about the issue.

That got me wondering about how far someone could use that answer and still maintain that it is useful to figure out what the metaphysics of our world is by supposing that quantum mechanics applies to the entire universe. My worry is this. By using the ‘gravity is negligible’ reason, one is admitting that quantum mechanics is really just another effective theory — it has a limited domain of application. If so, then either

  1. One thinks that in general it is legitimate to derive metaphysical conclusions using effective theories, or
  2. One thinks that there is something special about quantum mechanics as an effective theory, which allows one to derive metaphysical conclusions from it, as opposed to other effective theories that are typically ignored (e.g. effective field theories).

If one goes with 1., then it seems to me that the right way to do scientifically-informed metaphysics is to take the various theories we have as each being informative about their respective domains of applicability. This has the implication that we should not be applying quantum mechanics to the entire universe and taking the metaphysical implications of that seriously. For it is classical theories that are most effective at large size scales, not quantum mechanics.

As for 2., I am still struggling to imagine what could be special about quantum mechanics that licenses us to treat it in a different way from other effective theories. One possible reason is that one thinks that the most important aspects of quantum mechanics will still persist in a ‘final theory’ which applies to the entire universe. But whatever these preserved aspects are, it’s not clear to me that they are the same aspects as those that lead to the traditional philosophical problems in quantum mechanics. It might be that the mathematics of the final theory is such that the problems with locality and whatnot that manifest themselves in quantum mechanics are somehow dodged. One can apply the same consideration to other issues in philosophy of physics. Maybe underdetermination in general relativity won’t actually translate to an underdetermination problem in the final theory.

In addition, if you look at the history of physics, it doesn’t seem to me that the aspects of older theories that are preserved in newer theories are those which tend to preserve philosophical problems in the older theories. It doesn’t seem to me as though any of the aspects of classical physics that are preserved in quantum mechanics are those that are philosophically problematic for either theory. In other words, the robust aspects of physical theories often aren’t those that lead to traditional philosophical problems.

Someone help me out here. I seem to be missing out on a lot of fun by being so pessimistic about this enterprise of reading metaphysics off ‘fundamental’ theories.

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13 Responses to Metaphysics and Effective Theories

  1. Jonathan Livengood says:

    Could you say a bit more about which metaphysical issues you have in mind?

    I wonder whether you think there might be effective metaphysical theories corresponding to what you are calling effective physical theories. That is, maybe the issue isn’t so much about deriving metaphysical conclusions but about how those conclusions are understood — about what the metaphysics does for us.

  2. Many worlds, nature of probability in QM, superluminal causality, locality/separability, determinism, nature of space and time.

    And oops, when I wrote ‘underdetermination in general relativity’ I was really referring to the hole problem, which is about determinism, although it relies on the distribution of mass not determining the structure of space.

    And I fully support the notion of effective metaphysical theories.

  3. wolfgang says:

    “figure out what the metaphysics of our world is”
    poor Wittgenstein is rotating in his grave and/or his ghost running around in a Vienna circle

  4. Alan says:

    Wow, this is a really cool post that hints on a lot of critical issues in contemplation of comprehensive view of the universe. I only wish that I understood more than like 25% of it, lol.

    But really, this is terribly fascinating while at the same time I don’t have the background to understand it.

  5. Anirudh Kumar Satsangi says:

    Radhasoami Faith View of Modus Operandi of Creation of Universe
    There is cosmological evidence for God and the Universe existed before Big Bang please.
    Stephen Hawking writes in The Grand Design, “It is not necessary to invoke God to light the blue touch paper and set the Universe going.” Hawking said the Big Bang was merely the consequence of the law of gravity. In A Brief History of Time, Hawking had suggested that the idea of God or a divine being was not necessarily incompatible with a scientific understanding of the Universe.
    Although Hawking is very close to Truth yet he is not perfect in his views while discarding the role of divine being. I consider the role of eternal gravity uppermost but I strongly differ with Hawking on the role of divine being. I consider Divine Ordainment is the cause of Creation of Universe.
    Now I give Radhasoami Faith view of Creation Theory. In Sar Bachan (Poetry) composed by His Holiness Soamiji Maharaj the August Founder of Radhasoami Faith the details of creation and dissolution has been described very scientifically. It is written in Jeth Mahina (name of Hindi moth) in this Holy Book: Only He Himself (Supreme Father)and none else was there. There issued forth a great current of spirituality, love and grace (In scientific terminology we may call this current as gravitational wave). This is called His Mauj (Divine Ordainment). This was the first manifestation of Supreme Being. This Divine Ordainment brought into being three regions, viz., Agam, Alakh, and Satnam of eternal bliss. Then a current emerged with a powerful sound (this was the first Big Bang). It brought forth the creation of seven Surats or currents of various shades and colours (in scientific terminology we may call it electromagnetic waves). Here the true Jaman or coagulant was given (in scientific terminology this coagulant may be called as weak nuclear force and strong nuclear force). Surats, among themselves, brought the creation into being.
    These currents descended down further and brought the whole universe/multi verse into being i.e. black holes, galaxies etc. were born.
    I would like to add further that sound energy and gravitational force current are non polar entity and electromagnetic force is bi-polar. Hence spiritual polarization, if occurred, is occurred in the region of Sat Lok and region below to it only.
    Infinite expanse of gravitational force field is the region of dark energy.

    In Bible it is written that in the beginning was the Word; the Word was with God; and the Word was God.
    According to Radhasoami Faith “Shabd (Word) is the beginning and end of all. The three loks (worlds) and the fourth Lok, all have been created by Shabd.” (Sar Bachan Poetry)

  6. wolfgang says:

    >> electromagnetic force is bi-polar
    not only the electromagnetic force

  7. Anirudh Kumar Satsangi says:

    Perhaps you will agree with me that gravitational force is non-polar and sound energy is also non-polar. Electromagnetic force as well as weak and strong nuclear force are perishable but gravitational force is imperishable.

  8. Anirudh Kumar Satsangi says:

    Modus Operandi of Radhasoami Faith View of Creation – Part II
    Here the true Jaman (coagulant) was given. The spirituality coagulated as it were, and Surats (spirit entities), among themselves, brought the creation into being. Thereafter, another Jaman (coagulant) was given. Regions from Agam Lok (Inaccessible Region) to Sat Lok (True Region) were created during the first creational process. That creation is true. That region is eternal. There is no trace of evil and suffering. This was the creation for many Yugas and ages. Then there appeared a dark coloured current
    That current appeared like a dark coloured stone set in a white one and was absorbed in the Darshan of True Being. Then there appeared two Kalas i.e. currents (viz. Niranjan and Jyoti) and they together evolved the creation of five Tattwas (elements) four Khans (species, categories of life) and three Gunas (qualities). The three Gunas (qualities) brought about the expansion and proliferation . They created Rishis and Munis (sages and holy men), gods and godly human beings and demons. Egotism then increased much. Niranjan separated himself from the rest, putting the burden of looking after the creation on them. Nobody could know of Niranjan. Even the Vedas referred to Him as Neti Neti (Not this, Not this). They did not get Darshan (Vision) of Niranjan. They made conjectures. Then how can anybody have knowledge of Sat Purush (True Being), Source of Niranjan and all that exists.

    Scientifically here Jyoti represent three Fundamental Forces of Quantum Mechanics i.e. electromagnetic force, weak nuclear force and strong nuclear force. NIRANJAN is the fourth Fundamental Force i.e. Gravitation Force.

  9. wolfgang says:

    >> Then there appeared a dark coloured current
    where did it come from?

  10. Anirudh Kumar Satsangi says:

    According to Radhasoami Faith the entire universe is broadly classified into three regions viz., Pure Spiritual Region, Subtle Material Region and thirdly Gross Material Regions. If we work for a scientific analogy to these regions we can put like this – Pure Spiritual Region is predominantly the Region of Gravitational Force Current, Subtle Material Region is predominantly the region of Electromagnetic Force Current and Gross Material Region is predominantly the region of Weak Nuclear Force and Strong Nuclear Force Currents.

    Dark coloured current appeared to have originated from the outermost layer of Pure Spiritual Region.

  11. wolfgang says:

    >> Dark coloured current appeared to have originated from the outermost layer of Pure Spiritual Region.

    you must be wrong. you told us
    “That creation is true. That region is eternal. There is no trace of evil and suffering.”

    how can the dark current appear from the outermost layer of the pure region if there was “no trace of evil” ??

  12. Anirudh Kumar Satsangi says:

    Why we should presume that dark current represents evil?
    Kindly refer to my comment dated February 15, 2011 above. It is mentioned, “This Divine Ordainment brought into being three regions, viz., Agam (Inaccessible), Alakh (Imperceptible) and Satnam (True Being) of eternal bliss.” Then a current emerged with a powerful sound (First Big Bang). It brought forth the creation of seven Surats (various levels of energy) or current of various shades and colours. I hope things are clear now.

  13. The subject QM is a daunting subject and this barrier is the reason for the fear.. I want to know ether QM really a modern philistine?

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