Minimalism in Physics (updated)

Truth is ever to be found in simplicity,

and not in the multiplicity and confusion of things.

-- Isaac Newton

[Note: 
In using the term “minimalism” in evaluating styles of physics, I am importing  into the philosophy of science  a term mostly associated with the arts.  The move may or may not be fruitful.  But here is a well-known parallel move, from Gerald “Mr. Themata” Holton, in The scientific imagination (1978), p. 7:

I have proposed … thematic analysis (a term familiar from somewhat related uses in anthropology, art criticism, musicology, and other fields).  ]

The whole enterprise of physics, from ancient times to today, is itself  in one sense  Minimalist, in that it seeks to sweep aside the riot of epiphenomena, and to discover underlying laws, from which that riot derives.  It does not so much banish the fullness of reality, as bracket it:  we hope later to derive much of it back, in an explanatory manner.  (Note:  Not quite the same thing as Reductionism.)

To some extent, all rational inquiry ‘minimizes’ -- idealizes, works with toy models, etc.   Some more than others -- economics notoriously so, tossing out so much bathwater that sometimes the baby goes missing.   Others roll up the sleeves of their labcoats and go in elbow-deep to the mess of reality, little bothering with economy or philosophy.   Chemists, in particular, seem perfectly content to potter about in labs, to discover stuff, invent stuff, patent stuff.  They literally multiply entities, in that they invent chemicals that weren’t there before.   Whether they thereby multiply them beyond necessity (mustard gas, thalidomide,  napalm, LSD) is a matter of individual taste.  But certainly the ethos is anything but austere.

And likewise, for the most part -- biology, geology, astronomy, engineering, what have you. 

But modern physics  raises parsimony to a central tenet, almost the prime purpose of the whole enterprise as currently understood.  This development being by now taken for granted among those of the guild, it may not be apparent how odd this really is.

The goal for some time has been the “Theory of Everything”.  This certainly sounds like a Maximalist program:  but really it is not.   For the knights who pursue this grail do not actually intend to explain any of the things that real people care about   and that motivated the enterprise of physics in the first place:  why the sky is blue, why snowflakes are the way they are, why clouds are shaped that way, what lightning is all about, why airplanes can fly…  (Purported explanations of these things exist, but the ones I’ve heard seem all fallacious.)   Instead, they want to wrap their arms around a passel of abstractions, so complex as to leave the plain man -- nay, any but the professional physicist -- behind many decades ago, and show that, at a still deeper level, they are all but facets of One Big Thing.  (Hedgehog physics, we might dub this.)  This is Minimalist, and ferociously so.

It may be objected:  All that is nothing but plain reductionism, which is simply to say:  Science.  No call to drag in an arts-related term like “Minimalism”.  -- But I believe there is an aesthetic dimension -- seldom mentioned in journal articles, though over-emphasized in popular writing -- which lies outside the bare logical necessities.  As,

“There shouldn’t be laws of physics,” Strominger maintains. “There should be just one law, and it ought to be the nicest law around.”

(Quoted in Shing-Tung Yau, The Shape of Inner Space (2010), p.  14.)

Gerald Holten, characterizing the attitude of Einstein (The scientific imagination, p. 281):

At stake was nothing less than finding the most economical, simple, formal principles, the barest bones of nature’s frame, cleansed of everything that is ad hoc and redundant.

In his own personal life, the legendary simplicity of the man was an integral part of this reaching for the barest minimum on which the world rests.

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Central to the program is the “unification” of the various fundamental forces -- meaning, showing them to be symmetry-broken castoffs of an original single Force.    An analogy in evolutionary biology is explaining various related species  as having descended under various environmental pressures  from a common progenitor.   Only -- in physics, the enterprise is far more audacious than this analogy would suggest, if all you are thinking of are the breeds of dog, or the various canine species, or even the various land-mammals.   The forces are so fundamentally different in their phenomenology, that the task is more like tracing the common descent of the penguin, the echinoderm, and the paramecium.   Or even the mastodon, the gnat-swarm (considered as a sort of collective entity), and the sand-dune.   A tall order.

The reason so hubristic a program could come into existence despite the odds, is that it had an early success:  Maxwell’s unification of electricity and magnetism, back in the nineteenth century, truly a monument of the human intellect.  Now, later analysis has suggested that this success was something of a lucky fluke:  in the four macroscopic dimensions in which we reside, electricity and magnetism are both expressed by a vector.  You can not only analogize these, the one to the other, but calculate with them in the ordinary way -- say, forming their cross-product to get the Poynting vector.  In higher dimensions, electricity would be a vector and magnetism would be a tensor, and they would not play so nicely together.

The next success along these lines was far spookier:  the unification of electromagnetism with the “weak force”, into an unassuming-sounding entity called electroweak.   Now, this is far more bizarre than it seems. Electricity and magnetism were always rather like Batman and Robin, typically showing up together in the lab.  Whereas the weak “force” seems, to my untutored mind, like a force in some Pickwickian sense, like the  “force” of a metaphor in a poem.  A thing more different than electrostatic attraction or repulsion  can scarcely be imagined:  it deals neither in repulsion nor attraction, but rather in a handful of obscure and scarcely explicable processes such as beta decay.   Even to have conceived the project of their unification  was an act of extraordinary intellectual audacity;  the eventual success is, well, beyond any but specialist comprehension.

This new composite entity, this hippogriff, the electroweak, was subsequently unified with the “strong force”, yielding the hyperweak of today’s Standard Model.   The next -- and long elusive -- step, is the unification of that with gravity.   Now, to your average toddler, the natural analogy would be rather between electrostatic and gravitation attraction -- both, in their simple nonrelativistic forms, central forces obeying an inverse-square law    But your average toddler, like your average Nobel-Prize-winner-in-anything-but-Physics, would be mistaken.   And so the torch has passed to an ever-more-esoteric brotherhood, in particular  the magi of String Theory:  pale, spectral beings, who neither eat nor defecate, and whose results -- well, they do not as yet have anything so vulgar as actual verifiable physical results, mind you, but they do have theories, and conference papers, incomprehensible to all but the magi.  That does not mean they are on the wrong track;  perhaps they, and they alone, are on the right track, in which case, the more fools we.

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A startling development in some corners of recent physics  is an actual ‘Maximalism’ -- basically, the catastrophic breakdown of any parsimonious project, yet not taken as a reductio ad absurdum of reductionism itself, but rather embraced, by amor fati (a fancy name for making the best of a bad bargain).   No longer can one really -- nor does one aspire to -- explain anything, since everything that might exist, does exist, and the (now uninteresting) facts of the matter in our own neck of the woods  can be chalked up to Selection Effect.  (We satirized this Rabelaisian Fay ce que voudras  here).   

Templeton-Prize winner Paul Davies,  in The Goldilocks Enigma (2006), p. 264, takes rather understated notice of this:

The disadvantage of the multiverse theory is that it invokes an overabundance of entities, most of which could never be observed, even in principle.  This profligacy strikes many people as an extravagant way to explain bio-friendliness.

Likewise, though for different reasons, the earlier Many-Worlds school (or cabal) of quantum theory,  in which entities -- again, entire universes in this case -- are multiplied, not simply beyond necessity, but beyond common decency.

The ethos of all this is atheistic -- a-anything, really.  It is perhaps no accident that Hugh Everett, an early pioneer of many-worlds, was (in Wiki’s words) “a committed atheist".  Or that the thélémisme of the distinguished hexagonal/pentagonal humanist  was taken up with gusto  by the diabolist Aleister Crowley, the stench of whose cinders may occasionally bother your nostrils, whenever a high wind blows up from Hell.

[Update 27 III 12]  Freeman Dyson in the current NYRB, reviewing a book by Margaret Wertheim about eccentric amateurs:

String cosmology is different. String cosmology is a part of theoretical physics that has become detached from experiments. String cosmologists are free to imagine universes and multiverses, guided by intuition and aesthetic judgment alone. Their creations must be logically consistent and mathematically elegant, but they are otherwise unconstrained. That is why Wertheim found the official string cosmology conference disconcertingly similar to the unofficial Natural Philosophy conference. The insiders and the outsiders seem to be following the same rules. Both groups are telling stories of imagined worlds, and neither has an assured way of deciding who is right. If the title Physics on the Fringe fits the natural philosophers, the same title also fits the string cosmologists.

[Note:  Dyson -- a notably fair man -- has long been a fixture of the Institute for Advanced Studies in Princeton; and the IAS, in recent years,  has been premier in string theory.  So Dyson's assessment here  is by no means that of an envious outsider.]

On the extra profusion of different string theories, a mathematician remarks dryly,

It was hardly an idea calculated to appeal to a man with a taste for desert landscapes  … There are more than 10^500 versions of string theory  lounging indolently about.

-- David Berlinski,  The Deniable Darwin (2009), p. 532-3

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It will sometimes not be obvious, which proposals are Minimalist in spirit.  Thus, imagine some wretched Nominalist, who balks at the infinite, and proposes that the numbers needed for physics  are finite -- specifically, the field of integers mod a prime p (necessarily quite large, to accord with observation).   Finite’s gotta be simpler, more minimal, than infinite, right?  Roger Penrose retorts (The Road to Reality (2004), p. 359):

A physical theory which depends fundamentally upon some absurdly enormous prime number  would be a far more complicated (and improbable) theory than one that is able to depend upon a simple notion of infinity.

More precisely:   The problem is not essentially that the number is so large, but rather, with infinitely many primes to choose from, the choice would seem arbitrary:  in much the same way that the omniscient computer in  The Hitchhiker’s Guide to the Galaxy reveals, quite disappointingly, that the Meaning of Life is … “26”.

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Differing from a theory-wide programatic theoretical minimalism, is a kind of personal cognitive-epistemological economy, described by Gerald Holton, The scientific imagination (1978), p. 158:

Fermi ordered the overwhelming and vast amount of knowledge  into a set of very few principles and ‘cases’, which allowed him to understand almost any new problem as an example of one of about seven primitive or primary physical situations.  Fermi would return throughout his career  to a listing or digest of the chief ideas in physics, which he had made when he first organized the field for himself as a young student.

Our own thoughts about such Leading Ideas in other areas, may be surveyed here.

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A curious philosophico-cosmogonic anticipation of the TOE vs. Landscape divide  goes back several hundred years:

Leibniz … assure que la perfection de Dieu ne lui permettait pas de procéder d’autre manière que de la meilleure … mais Thomas d’Aquin sait que, créant du fini, un Dieu infini pouvait librement créer un nombre illimité d’univers différents, tous bons  et chacun commençant de manière différente.

-- Etienne Gilson, Linguistique et philosophie (1969), p.  163

And indeed, though Leibniz coinvented the calculus, we must say that, here, from a mathematical standpoint, it is Saint Thomas who is closer to the target.

Bonus quote:

Willem de Sitter found an exact solution to Einstein’s field equation … having no matter at all. … Why should we be interested in such a universe?  Because the real universe is of rather low density …

-- J. Richard Gott, The Cosmic Web (2016), p. 16

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Metaphysical Infrastructure

The widest postulate of rationality is that the world is rationally intelligible throughout… The whole war of the philosophies is over that point of faith.

-- William James,  The Principles of Psychology (1890)

… unverifiable, unfalsifiable, and yet not arbitrary conceptions or hypotheses -- a class to which I have referred as thematic presuppositions … necessary for scientific work

-- Gerald Holton, The scientific imagination (1978), p. 99

[Postmodernism uses] a technique of metatheory (theory about theories), by which scholars analyze  not so much the subject-matter of the scientific discipline  as the cultural and psychological reasons  particular scientists  think the way they do.  The analyst places emphasis on “root metaphors”, those ruling images in the thinker’s mind  by which he designs theory and experiement.

-- Edward O. Wilson, Consilience (1998), p. 42

There is no such thing as philosophy-free science;  there is only science whose philosophical baggage is taken on board without examination.

-- Daniel Dennett, Darwin’s Dangerous Idea (1995)

… Whewell’s views about latent axioms, things which  at first  are not even credible, but which settle down into first principles.

-- Augustus de Morgan

Metaphysics (what we think reality is fundamentally like) can affect our ethics.

-- Edward Craig,  Philosophy: A Very Short Introduction (2002), p.  43

Awhile back, in a ground-breaking article, I proved the existence of coffee-cups.  But before the International Philosophic Society officially crowns this achievement with the name  of Justice’s Theorem (or even Justice’s Great Theorem, in contradistinction to Justice’s Little Theorem, to appear), we must confess that the proof was made possible only by the use of certain major metaphysical assumptions, up to and including the existence of God.  (Indeed, in a slightly strengthened version, known as  “Boshaft-ist-Er-Nicht” -- which still falls well short of God as conceived by Christianity.  So, you can still believe in coffee-cups without being Christian, though it helps.)  Given these assumptions, the actual deduction could have simply been “left as an exercise for the reader.”  So perhaps it should be demoted to, say, Justice’s Corollary, or even David’s Afterthought.

That was, of course, the whole point of the exercise:  to argue that many things we take for granted, and ought to take for granted, are not in fact straightforwardly empirically given, but must be derived with the aid of fundamental metaphysical principles,  which we seldom explicitly acknowledge in daily life, and which it has become the fashion  to deny.

Thus, Paul Davies, a physicist and a Christian, in The Goldilocks Enigma (2006), p. 262:

If there is no coherent scheme of things, then the success of the scientific enterprise to date  is rendered totally enigmatic, and science can be pursued only with a completely unjustified faith  that the methods used hitherto  will continue to uncover reasonlessly existing order  beneath the surface appearance of things.

A “coherent scheme of things” is basically a metaphysical notion.

He goes on to characterize the adaptationist fantasy (which we satirized here), that

brains have evolved to recognize patterns, and that -- again for no reason -- the deep patterns of physics and cosmology  resemble the patterns of the everyday world on our planet (which in fact they mostly don’t).

This all seems rock-solid.  In the satire, I wrenched it up a notch, noting the even greater implausibility of far-flung mathematicians from many different times and cultures  unanimously agreeing on the truth of such things as the Urysohn Metrization Theorem, which are farther from our experience even than quasars or quarks. 

On the other hand, where Davies, a believer, nonetheless has recourse to the phrase “unjustified faith” to belittle a credulous embrace of the scientific endeavor, Cohen & Nagel (secularists) use the same word “faith” (in the sense of naïve faith) to belittle a belief in something very like a “coherent scheme of things”:

The reader may perhaps believe that the inference from the observed conjunction of factors  to an invariable conjunction  is legitimate in virtue of the “uniformity of nature”.  We shall not disturb the reader’s faith in this familiar doctrine  at this point.  But, as we shall see presently, such a faith has no evidential value  in demonstrating the existence of invariable connections.

-- Morris Cohen & Ernest Nagel,  An Introduction to Logic and Scientific Method (1934), p. 254

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Philosophers by profession attempt to dig behind the appearance of things, and to uncover unsuspected incoherencies and hidden assumptions.  People just mowing their lawn, do not.   Midway between these  lie the scientists.

Since the scientific investigation of nature ipso facto strives to get behind the phenomena, its practitioners -- even if not otherwise philosophically inclined -- may be led to confront such assumptions.   Thus, going way back, and down almost to our day (until atomism, Mendelism, and quantum theory put something of a kink in it), is the Principle of Continuity.   Thus Wikipedia (I quote from the German, since the English in this case is a bit lame):

„Natura non facit saltus“ (lateinisch für „Die Natur macht keine Sprünge“) ist eine Grundannahme der antiken Philosophie und Naturwissenschaft seit Aristoteles (bzw. schon seit den Eleaten: altgr. Ἡ φύσις οὐδὲν ποιεῖ ἅλματα.). In dieser Form stammt das Axiom von Carl von Linné (1707-1778) aus seinem Werk Philosophia Botanica (Stockholm, 1751). Der Gedanke wurde später im biologischen und geologischen Gradualismus aufgegriffen.

Mit dem Satz wird ausgedrückt, dass sich Prozesse bzw. Veränderungen in der Natur nicht sprunghaft und plötzlich - diskontinuierlich - vollziehen, sondern prinzipiell kontinuierlich bzw. stetig.

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A magnificent expression of this view was the Great Chain of Being, stretching up from the paramecia, through the Humble Woodchuck, mankind, and the mighty penguin, up to cherubim and archangels and beyond.

This notion is closely related to the Principle of Plenitude, likewise of ancient date:  and likewise leading to startling modern updatings, in the Many-Worlds fantasy of quantum theory, or the Multiverse (currently all the rage.)  Edward Harrison (Cosmology, 2000, p. 268) characterizes it thus:

The principle of plenitude:  everything that is not forbidden is compulsory.  Whatever is possible, must exist.  In science we see that nature is plenitudinous rather than parsimonious.

A stark contrast, then, between the (plenitudinous) objects of inquiry, and our (parsimonious) ideal of explanation.  (More on parsimony here.)

 

Or again,  “Nature abhors a vacuum”.   In the universe of our forefathers, what would otherwise have been the vacuum  was filled up with the ether;  now it is clogged with quantum foam.

Or:  Occam's razor (" lex parsimoniae"), the implement of choice for those seeking Unification.

And, 

According to the rationalistic doctrine, the causal principle is a necessity of thought (Denknotwendigkeit), an a priori regulative principle, hence a presupposition rather than a result of science.  This is the opinion of the Leibnizians, for whom the causal principle is nothing but a form of the principle of sufficient reason.

Mario Bunge, Causality and Modern Science (1959, 1963)

Nonlinear systems do not 'obey' the 'principle' (theorem) of superposition (of forces, displacements, and so forth) ... The 'principle' of superposition may be regarded as the specific form taken in physics  by the hypothesis of the independence of causes.

Mario Bunge, Causality and Modern Science (1959, 1963)

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Note, though:  metaphysical infrastructure, not metaphysical foundations.   Metaphorically, these principles are like the skeleton in the body, which, though fundamental, is not more important than the blood or the flesh.

It is difficult, indeed, to come up with metaphysical foundations for science out of metaphysics itself.  Thus, consider Kant.  After thinking long and hard, abstractly (none of us could have done any better, within those limits), he managed to convince himself that having extension was of the very essence of physical objects, thus “All bodies are extended” is analytic.   Musing further, he concluded that having weight lay outside of what it meant to be a body, hence “All bodies have weight” is synthetic.

Presumably this last hunch was not a prescient anticipation of massless particles like photons and (perhaps) neutrinos.   In any event, the same arena furnishes examples of bodies that do indeed have rest-mass, but (if indeed they are point-particles) no extension:  electrons.

Reductionism, when its status is not that merely of a convenient method, but of a tenet or article of faith, might be deemed a metaphysical principle.

Edward Wilson, in Consilience (1998), rather stands the matter on its head, since he refers to science itself as metaphysical: “Science offers the boldest metaphysics of the age.”   He would seem to be using the word in some different sense. -- In any event he is not consistent in such use, as he later goes on to warn, more conventionally, against "the pitfalls of metaphysics".

Anyhow:

The prototype of a body is a coffee-cup, with extention, mass, hardness, etc. etc.   Kant’s musings really added nothing to our understanding of these.   Subsequent scientific results did add something:  an object can lack mass, or lack extension, or both, or neither.  Tiens, tiens.   To what extent we assimilate such items to our prototype of a "body", is more a matter of metaphor than of science or philosophy.  How is an electron like a coffee-cup?  like the old riddles of childhood and thereafter (“How is a blonde like a bottle?” -- “They’re both empty from the neck up.”)

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I'm not particularly wedded to this term "metaphysical", b.t.w.; mostly it is just nicely provocative.  What I'm talking about here is related to what Gerald Holton discussed using his favorite terminology of themata.  (I once visited Holton in his office one summer;  he grabbed my lapel and launched into the topic of themata, like the Ancient Mariner.)  Thus ( The scientific imagination (1978), p.20):

This prototype for explanation (classical causal sequences  account for observed accident or disorder) is a thematic commitment.  It is not an experimental or logical necessity.

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Now for some more recent methodological/metaphysical assumptions of physics.

Edward Harrison, Cosmology (2^nd edn. 2000), p. 454:

We are unable to obtain a model of the universe without some specifically cosmological assumptions that are completely unverifiable. (George Ellis, “Cosmology and Verifiability”, 1975).  The problem is that we observe isotropy, which we cannot explain,  and we assume homogeneity, which we cannot verify.

As you see, working scientists are sometimes acutely aware of such epistemologically awkward states of affairs.   But here’s another one I’ve noticed, and am not too sure that it is widely recognized as a tacit working assumption:

~ Do I contradict myself?  Very well then, I contradict myself.

It’ll all work out in the end. ~

Gerald Holton, in his detailed investigations of the rival Ehrenfest/Millikan experiments in verifying and quantifying the hypothized granularity of electricity ("Subelectrons and Presuppositions", reprinted in The scientific imagination, 1978), refers to the "suspension of disbelief" on the part of an experimenter, faced with the blooming buzzing confusion of his contradictory daily results.  But this epistemological grace period was envisioned as lasting over the course of a series of experiments, not for decades or centuries.

Thus, classical physics predicted that orbiting electrons would continuously radiate away energy -- and thus collapse into the nucleus.  Hence, atoms could not exist.  Nor was there a glimmer of a solution on the horizon.  Physicists just lived with it.  When a solution of sorts did come, with quantum mechanics, it was of an utterly strange and unforeseen sort.

The history of science -- of physics in particular -- is riddled with such intellectually scandalous states of affairs.   And yet the trustful, What-me-worry stance of the everyday scientist  is wise in its way -- it’s that or quit physics (or discover quantum mechanics).    Perhaps, without explicitly saying so, they inwardly believe that the universe is an orderly and rational place, and that our fumbling steps are somehow guided, and that the Plan unfolds in time.   Perhaps they believe  (in their heart of hearts) … in Him.  For if not -- whence the assurance of (A) ?

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Brian Greene, The Fabric of the Cosmos (2004), p. 224:

Physicists have elevated  symmetry principles  to the highest rung on the explanatory ladder. …. Physicists believe these theories are on the right track because, in some hard-to-describe way, they feel right, and ideas of symmetry are essential to this feeling.   … Symmetries are the foundations  from which  laws  spring.”

The manly admission of the role of (most unmanly) “feeling” here, is well in point.  But it is not really subjectivism -- the personal equation -- that is in play here.  Rather, a level of explanation  deeper than that of laws,  which we cannot grasp  with our intellect.

He goes on (p. 243):

Symmetry is the essential consideration  allowing us to comprehend space and time when applied to the unuiverse as a whole.  Without invoking the power of symmetry, we’d be stuck at square one.

Well I recall, many years before, a lecture by Steven Weinberg, in which he mentioned Galileo’s sticking to circular planetary orbit, despite Kepler’s having previously demonstrated their elliptic shape.   The occasion, in most settings, of indignant Whiggish sniffs; but Weinberg wisely -- like a bolt it was -- demurred:

Galileo was perfectly within his rights to privilege such symmetry, it lies at the heart of all subsequent physics.  His error, merely, lay in mistaking the planets, those -- not godlings, as for the pagans, but -- dull lumps of earth, as lying near the center of things.

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The principles lying perdu behind our practice, need not be recondite, but they are metaphysical (as opposed to empirical) nonetheless.  Thus the charming simplicity of the complicated Quine:

The so-called scientific method is a matter of being guided by sensory stimuli, a taste for simplicity in some sense, and a taste for old things.

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I do not intend to suggest a disjunctive dichotomy between “metaphysical” assumptions on the one hand, and empirical matters on the other.  Rather, there is a sort of hierarchy (not necessarily linear) of relatively-specific facts or principles, and relatively more general.  The former will be at the front of consciousness, in practical work;  the point of the present essay is to point to the latter, lest they be forgot.  But often, both levels will clearly lie within (say) physics.

Thus:

The only reason for introducing probabilities in the study of gases  is to obviate the insuperable mathematical difficulties which a direct application of the mechanical laws would involve.  The mechanical laws, however, are utilized indirectly, for it is by their means (and also by accepting the ergodic hypothesis) that the probabilities are computed.

-- A. D’Abro, The Rise of the New Physics (1939), vol. II, p. 945

And, concerning the alleged correlation of disorder and frequency of macrostates, Georgescu-Roegen comments (in The Entropy Law... 1971):

The proposition comes very close to being a metaphysical principle. ... It is this metaphysical essence which accounts for the insuperable difficulties encountered in justifying the new Entropy Law,  either experimentally,  or analytically by derivation from other basic laws.

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Edward O. Wilson, Consilience (1998), p. 198, lists the four metascientific desiderata for any scientific theory:  parsimony; generality; consilience; predictiveness.

It is in point of consilience that he finds Creationism wanting.  “God may exist, He may be delighted with what we are up to on this minor planet, but His fine hand  is not needed to explain the biosphere.”

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Unlike considerations of symmetry or simplicity, ideas of causality do not, I believe, generally guide research as (examined or unexamined) metaphysical assumptions behind the scenes.   Rather, research proceeds on its own terms, and periodically is discovered to have implications for our notions of causality.  So, I will not here comment on that.

In the public and legal arena, by contrast, very practical decisions are influenced by our hazy ideas of causality.  A stab at clarifying a couple of these: here  and  here.

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Miscellaneous quotations on the matter of metaphysical underpinnings (with attendant vocabulary):

Unity of science” … “physical forces”  were not merely directing ideas or hypothesis of scientific endeavor:  they became almost objects of worship.  They were more than methods of research -- they became a Weltanschauung.

-- Ernest Jones, Freud: the Formative Years (1953), p. 43

Gauge invariance is not a physical principle, but a logical principle.

-- Russell Standish, Theory of Nothing (2006; 2nd edn. 2011), p. 121

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The tacit ideational underpinnings need not be strictly metaphysical;  it can be straightforwardly practical:

The real issue in this connection is not the one commonly debated, “What are the criteria for the selection of patients?”, but the underlying, usually unstated assumption, “Criteria for selection are good”.  There are strong theoretical and practical reasons … for saying that  “Selection of patients is not good” … The best policy is to pick patients at random … to increase the heterogeneity of the group.

-- Eric Berne, Group Treatment (1966)

“Tacit principle” cf. “pious assumption/lip-service”:

At present, the only statement that can be made is that it is helpful for a group therapist to have had personal experience as a patient in a therapy group.  But even that   is only a pious assumption, since  in fact  it has never been critically evaluated, and so still remains part of the lore of institutional group therapy.

-- Eric Berne, Group Treatment (1966)

[Bonus quotes]

Fundamental to knowledge are certain “analytical hypotheses” that go beyond the evidence.

-- Noam Chomsky, “Quine’s Empirical Assumptions”,  in:  D. Davidson & J. Hintikka, eds. Words and Objections (1969, 1975), p. 60

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