In what sense is QCD autonomous?

The data that theorists sought to explain and whose work resulted in QCD were created by instruments designed on principles that are not based on QCD.

In what sense is QCD autonomous?

The data that theorists sought to explain and whose work resulted in QCD were created by instruments designed on principles that are not based on QCD. — Frederick KOH

In the context of effective field theories, the autonomy at issue is the autonomy of a large-scale, low-energy, theory (such as QED) relative to a smaller-scale, higher-energy, theory (such as QCD). I've already explained the sense in which it is autonomous. In addition to Crowther's paper, referenced earlier (Decoupling emergence and reduction in physics), you can also look up Jonathan Bain, Emergence in Effective Field Theories (2012).

When the discussion touched chemistry, you used the term "autonomous law" instead of "autonomous theory".

Suppose this question was asked in 1835:

Are the following what you consider to be autonomous laws:

Coulomb's Law
The Biot-Savart Law
Oersted's Law
Faraday's Law of Induction — Frederick KOH

You often present alleged examples of reduction, which I then proceed to analyse. You then ignore my analysis, ask more rhetorical questions, and then challenge me with more examples. What's the point in me analyzing and discussing your own examples in details if you are just going to ignore the analysis again? This new Gish gallop of yours is you answer to my request that you would give me some inkling of the meaning of your claim that: 'It means that "fundamental" theories have two means of being "transported" from their original birthplace to other areas of inquiry.'

This was beginning to look like an argument. Can you make it a little more explicit?

You often present alleged examples of reduction, which I then proceed to analyse. You then ignore my analysis, ask more rhetorical questions, and then challenge me with more examples. What's the point in me analyzing and discussing your own examples in details if you are just going to ignore the analysis again? This new Gish gallop of yours is you answer to my request that you would give me some inkling of the meaning of your claim that: 'It means that "fundamental" theories have two means of being "transported" from their original birthplace to other areas of inquiry.' — Pierre-Normand

The gish gallop was from you. From your own switch from "autonomous theories" to "autonomous laws", deftly, and with wiliness, hoping no one would notice that the term used has changed without you characterizing the difference.

I suspect the reason you are not answering is because these four laws developed in a way that is very different from the ones in chemistry.

Do you agree that these four laws developed in a way that is very different from the ones in chemistry? Are they autonomous laws?

I've already explained the sense in which it is autonomous. — Pierre-Normand

But also a sense which does not include instruments and experimental set up in a theory meant to be empirical.

The gish gallop was from you. From your own switch from "autonomous theories" to "autonomous laws", deftly, and with wiliness, hoping no one would notice that the term used has changed without you characterizing the difference. — Frederick KOH

That's not true. I took some pain to explain the sense in which individual laws can be said to be autonomous relative to the laws that govern the interactions between the material constituents in the lower-level theory. I had explained this here and here among other places.

But also a sense which does not include instruments and experimental set up in a theory meant to be empirical. — Frederick KOH

This complaint is rather fuzzy. In what way should the sense of the word autonomy "include instruments and experimental set up"? Each theory has its own set of observational concepts and relies on specific types of experimental setups. Reductibiliy (or autonomy) concerns derivability (or lack thereof) of the laws in one set from the laws in the other set. It is a matter of theoretical analysis whether or not such a derivability is possible. But it is a matter of empirical inquiry whether the laws governing the entities belonging to either levels are satisfied.

Do you agree that these four laws developed in a way that is very different from the ones in chemistry? Are they autonomous laws? — Frederick KOH

You were postulating that your question regarding the autonomy of those laws was being asked in 1835. One would have to look up what the status of each of those laws, and of the broad theories they were a part of, were at that time. When a law is first being derived empirically from the identification of some regularity, or of manifest causal networks, in a set of observations and experiments, then the question of the autonomy or derivability of those laws relative to another as of yet unknown theory is an open question. In the case of the laws of electromagnetism and electrodynamics, the question of their potential reduction began to make sense when quantum field theory was developed. It turned out that relative to their "realization base" (higher-energy effective field theories) the laws of quantum electrodynamics were partially autonomous since they involved different degrees of freedom and were, in a sense, multiply-realizable.

You were postulating that your question regarding the autonomy of those laws was being asked in 1835. One would have to look up what the status of each of those laws, and of the broad theories they were a part of, were at that time. When a law is first being derived empirically from the identification of some regularity, or of manifest causal networks, in a set of observations and experiments, then the question of the autonomy or derivability of those laws relative to another as of yet unknown theory is an open question. In the case of the laws of electromagnetism and electrodynamics, the question of their potential reduction began to make sense when quantum field theory was developed. It turned out that relative to their "realization base" (higher-energy effective field theories) the laws of quantum electrodynamics were partially autonomous since they involved different degrees of freedom and were, in a sense, multiply-realizable. — Pierre-Normand

There is something wrong when a specific question is asked and generalities are proffered in response. Especially when we know exactly what happened to those laws.

It is interesting that you managed to get from "the laws of electromagnetism and electrodynamics" to "quantum field theory" without mentioning Maxwell's equations. I am going to be charitable and assume that somewhere in "the laws of electromagnetism and electrodynamics" you include Maxwells equations. In either case it is either disingenuousness or ignorance that no mention how those four laws relate to Maxwell's equations.

This complaint is rather fuzzy. In what way should the sense of the word autonomy "include instruments and experimental set up"? — Pierre-Normand

What use is a theory, autonomous or not, it it does not come with means to connect it to experiments.

Each theory has its own set of observational concepts and relies on specific types of experimental setups. — Pierre-Normand

Those concepts and setups exist prior to and motivate the theories in question.

That's not true. I took some pain to explain the sense in which individual laws can be said to be autonomous relative to the laws that govern the interactions between the material constituents in the lower-level theory. I had explained this here and here among other places. — Pierre-Normand

And in the four laws I gave an example where what the material constituents were is not clear. Especially when we know the classical theory that came after.

It is interesting that you managed to get from "the laws of electromagnetism and electrodynamics" to "quantum field theory" without mentioning Maxwell's equations. I am going to be charitable and assume that somewhere in "the laws of electromagnetism and electrodynamics" you include Maxwells equations. — Frederick KOH

Well, yes. The classical theory of electromagnetism indeed incorporates its mathematical expression in the form of Maxwell's equations. Thank you for your generosity.

In either case it is either disingenuousness or ignorance that no mention how those four laws relate to Maxwell's equations.

So, was your point that the four laws that you mentioned somehow "reduce" to Maxwell's equations? With the minor caveat that Coulomb's law just is an approximation (i.e. it doesn't account for "retarded potentials") those laws can be regarded as being unified into a coherent field theory that has been formalized by Maxwell. (Full blown classical electrodynamics also incorporates the Lorentz force law).

I don't see this as a clear case of one theory being reduced to another. (And even if it were, that would lend no support whatsoever to Weinberg's "grand reductionism"; that would just be another instance of "petty reductionism", which pluralists and emergentists are happy to grant). Maybe your point is different. Again, when you have a point to make, if would make our discussion less cumbersome if you would just make it explicitly, rather than rely entirely on the mere asking of rhetorical or gotcha questions.

And in the four laws I gave an example where what the material constituents were is not clear. Especially when we know the classical theory that came after. — Frederick KOH

Sure. In that case you can't achieve reduction through appealing to a more fundamental theory that regulates interactions between smaller material constituents. Weinberg's "why?" questions would still be the question why those laws are valid, assuming that they aren't themselves fundamental. If Weinberg's "grand reductionism" were correct, then there would exist a more fundamental theory -- a reduction base for it (i.e. a theory that is closer to Weinberg's unique "final theory") -- such that those laws are causally and/or deductively determined by it. Maxwell's equations don't constitute such a reduction base, since they merely express those very same laws in a consistent and rigorous manner. Maxwell's equations don't answer the question why they themselves are valid.

The most obvious candidate for a theory that would serve as an appropriate reduction base for classical electrodynamics, according to Weinberg himself, would be a high-energy theory such as QCD. QCD is thus a theory that he deems to figure on the path towards his dreamed of final theory, with a GUT theory, and a theory of quantum gravitation also figuring further down this path. Unfortunately, as I've argued, effective field theories that are valid at different energy scales don't appear to reduce one another.

Those concepts and setups exist prior to and motivate the theories in question. — Frederick KOH

It's not generally the case that the empirical concepts that figure in a theory already were in use prior to the development of the theory. This would be to forget the theory-ladenness of observation. The theoretical understanding of the laws of a theory, on the one side, and the understanding of the empirical objets, relations and properties that populate the ontology of this theory, on the other side, more often than not grow together. The concept of a gene didn't predate the discovery of Mendelean inheritance. The understanding of the concept of mass and of force weren't quite the same before and after the development of Newtonian mechanics (or before and after Einstein's special theory or relativity), etc.

Again, when you have a point to make, if would make our discussion less cumbersome if you would just make it explicitly, rather than rely entirely on the mere asking of rhetorical or gotcha questions. — Pierre-Normand

Thank you for bringing this up. This is because you seem to want to define your way out of any counter-argument. How else do I pin down what you mean when you use terms that I have never seen any philosopher of science use?

As an exercise to anyone else still reading this thread, google "autonomous law" and see what you get.

I don't see this as a clear case of one theory being reduced to another. — Pierre-Normand

I am beginning to think that I will have to use the same reasoning as the proverbial judge who had to rule on what pornography is.

Thank you for bringing this up. This is because you seem to want to define your way out of any counter-argument. How else do I pin down what you mean when you use terms that I have never seen any philosopher of science use?

As an exercise to anyone else still reading this thread, google "autonomous law" and see what you get. — Frederick KOH

Steven Weinberg uses the phrase "autonomous law" in "Two Cheers for Reductionism", one of the two book chapters that you enjoined me to argue against and endeavored to defend. I also was quite careful in explaining how I was using the term, quite consistently with Weinberg's own use, to signify the irreducibility of such a law within a theory to laws and principles from some other more fundamental theory. The explanation why such autonomous laws obtain (answering Weinberg's "Why?" question) rather is to be found at the same level of theory. I first made use of the phrase in this thread in order to explain the idea of a merely partial autonomy from one theory to another; when you had seemed to think that the question of the reducibility (or autonomy) of a whole theory in relation to some other theorie(s) is an all or nothing matter.

I am beginning to think that I will have to use the same reasoning as the proverbial judge who had to rule on what pornography is. — Frederick KOH

The Maxwell equations don't constitute a reduction of the four laws that you mentioned in anything like Weinberg's sense of reduction. That's because, for Weinberg, reducing a law (or scientific principle) consists in explaining why this law (or principle) obtains in terms of a more fundamental theory. The Maxwell equations formalize the laws of electromagnetism in a precise and consistent manner. They don't explain why those laws are valid. As I reminded you -- and you ignored again -- that is precisely why Weinberg seeks to reduce QED (the quantum mechanical version of electrodynamics) to another higher-energy effective field theory such as QCD.

The Maxwell equations formalize the laws of electromagnetism in a coherent and consistent manner. They don't explain why those laws are valid. — Pierre-Normand

There is no scientific theory that does that!

There is no scientific theory that does that! — Frederick KOH

Which is precisely why you must seek some deeper reduction base -- a more "fundamental" theory -- in order to disclose at least one of the multiple "arrows of explanation" the alleged convergence of which ground Weinberg's grand reductionism. Weinberg's "arrows" always point from one law or principle of a theory to laws or principles from another theory. Else, in his view, the first theory (and its laws) would be freestanding and grand reductionism would fail.

When I say this:

There is no scientific theory that does that! — Frederick KOH

an example of a non-sequitur is this:

Which is precisely why you must seek some deeper reduction base -- a more "fundamental" theory -- in order to disclose at least one of the multiple "arrows of explanation" the alleged convergence of which ground Weinberg's grand reductionism. Weinberg's "arrows" always point from one law or principle of a theory to laws or principles from another theory. Else, in his view, the first theory (and its laws) would be freestanding and grand reductionism would fail. — Pierre-Normand

an example of a non-sequitur is this: — Frederick KOH

I agree that it is a non sequitur! It is Weinberg's non-sequitur. It is a non sequitur because there actually are lots of reasonable explanations why some specific laws within some theories obtain that aren't reductive explanations in Weinberg's sense.

Which is precisely why you must seek some deeper reduction base -- a more "fundamental" theory -- in order to disclose one of the "arrows of explanation" the alleged convergence of which ground Weinberg's grand reductionism. — Pierre-Normand

That is indeed the prejudice. It is entirely possible (as I mentioned earlier) that an exact law of nature at a higher level will perform the explanatory role. The conservation lawsand the 2nd law of thermodynamics perform similar roles.

As I also mentioned, a higher-level exact law may be the solution to the fine-tuning problem, and we have candidates for this.

And, given what we already know about reality, it is impossible that the "final theory" of physics can explain everything. We still need fundamental theories of life, information, computation, epistemology and consciousness to name a few.

The first step is to recognize the primary limit of scientific theory itself, for which purpose I introduce one example: that of quantum mechanics. Contrary to most pundits on the subject, quantum theory was not at all some new revolutionary discovery. Several thousand years ago, Vedic philosophers watched motes of dust in sunbeams and asked "what is the smallest thing that can exist?" Thereon, they reasoned, however small a mote might be, it would still have an inside and outside. But the inside and outside would have have to be smaller than the smallest thing. So, if it were the smallest possible particle, it would then be impossible to determine what is inside it and what is outside it. THEREFORE, they reasoned, matter consists of compartments of space, inside each one of which there may be solid matter or not, and it is impossible to determine which compartments contain solid matter, and which not, because the ability to measure the distinction would require the existence of something smaller than the smallest possible thing.

Fast forward to the modern world. Many are now still convinced that quantum theories and the Heisenberg uncertainty principle are 'discoveries of the way the world really is.' But they are not. They are the consequences of our own ability to comprehend the material world, and the experiments simply demonstrate that which Vedic philosophers deduced by reason several thousand years ago.

Science is only a model corroborated by experiment, and the model can only be as good as our minds can create. Within our brief time-bound existence, the ultimate nature of reality is beyond our absolute comprehension. When approaching the limits of science, we approach the limits of that which we can comprehend, which is the limits of our ability to reason, and not the actual limits of the material world--if indeed it exists independent of the domain of mind.

Those who dismiss domains of mind, independent of matter, have already dismissed much that can be explained. Attempting to explain to such minimalists any deeper understanding could be limited by their own lack of insight--while the minimalists will continue to deride attempts to explain alternative perspectives as flaky imagination. And with the exploding pseudosciences resulting from the decay of hermeneutic knowledge into the pseudodata of post-modernism, the minimalists can point to good examples. There are now many bizarre theories claiming to define consciousness perfectly in terms of quantum mechanics, or string theory, or whatever, because the actual metaphysical distinction between mind and matter still remains opaque to many people.

Similarly, many modern political theories are not really understood because people do not know the history of thought that went into their making. Most of their answers are no better than those provided by hypnotists seeking out your identity in a previous life, which even itself has been labeled a 'science' of 'regressive therapy.' To answer questions of politics properly, one must understand the theories which produced the questions, or it is no more than the blind stabs into an unknown dark, producing the ephemera of intangible and irresolvable debate that has already degenerated the 'age of enlightenment' into 'the information age.' First, simple data correlation slowly replaced analytical thought, over many generations of ignorant skepticism. From that, it was only a tiny step to the more rapid degeneration into the current 'post-truth era,' within which 'defining the narrative' replaces 'the search for rational truth' with an increasingly perilous rate of acceleration.

The first step is to recognize the primary limit of scientific theory itself, for which purpose I introduce one example: that of quantum mechanics. Contrary to most pundits on the subject, quantum theory was not at all some new revolutionary discovery. Several thousand years ago, Vedic philosophers watched motes of dust in sunbeams and asked "what is the smallest thing that can exist?" Thereon, they reasoned, however small a mote might be, it would still have an inside and outside. But the inside and outside would have have to be smaller than the smallest thing. So, if it were the smallest possible particle, it would then be impossible to determine what is inside it and what is outside it. THEREFORE, they reasoned, matter consists of compartments of space, inside each one of which there may be solid matter or not, and it is impossible to determine which compartments contain solid matter, and which not, because the ability to measure the distinction would require the existence of something smaller than the smallest possible thing. — ernestm

Which, apart from being poor reasoning, bears no resemblance to quantum theory.

Well. That surprises me. I thought the reasoning interesting and the similarity obvious. But as it is not on the point of this topic I will not digress.

Well. That surprises me. I thought the reasoning interesting and the similarity obvious. But as it is not on the point of this topic I will not digress. — ernestm

Yes, this issue may not be exactly on the point of this thread. But I agree with you that the reasoning is both interesting and relevant to features of quantum mechanics that bridge metaphysics and epistemology. I had mentioned earlier (I think in this thread) some similar reasoning that had put Heisenberg on the right path for the developments of his early formulation of QM (matrix mechanics). He explained his thought process in The Physicist's Conception of Nature.

Regarding the quality of the reasoning, there might be some obscurity in the argument, but those old Vedic philosophers don't strike me as being as being any less insightful than the early Greek atomists were.

There is a fundamental difference between the sort of reasoning exemplified by these Vedic philosophers - or for that matter by ancient atomists - and later scientific models like quantum physics (or atomic physics). The former is a priori reasoning, motivated by abstract (pseudo-)puzzles. It bears no relation to the motivations behind the later scientific models, and any resemblances between the two are accidental and superficial.

I think you miss the point. I did talk with a magazine editor about this today, and he agreed both that my point was valid, and that the point does require a great deal more explanation. Currently I am not ready to express it succinctly.

There is a fundamental difference between the sort of reasoning exemplified by these Vedic philosophers - or for that matter by ancient atomists - and later scientific models like quantum physics (or atomic physics). The former is a priori reasoning, motivated by abstract (pseudo-)puzzles. It bears no relation to the motivations behind the later scientific models, and any resemblances between the two are accidental and superficial. — SophistiCat

Many of the puzzles, as well as many of the insights, were real, it seems to me. There are both deep differences and deep similarities. If you read the intellectual biographical recollections of Heisenberg (or Schrödinger, or Einstein) you'll find that there are lots of philosophical and other a priori considerations that grounded their theoretical innovations. Of course there is a sort of interplay between theory and experiment that rests on the practice of the mathematical formalization of the laws of physics (and of the laws of some other special sciences) and the derivation of precisely quantifiable predictions (and explanations) that wasn't developed until recent centuries. This profound difference doesn't negate the profound similarities.