There Are No Quarks : Can You Prove Me Wrong?

CoIin
CoIin: Provocative title? Well, why not? Call it "Scientific Realism Revisited" if you prefer. Where to begin then?

Do quarks exist?

Of course they do

Um, how do you know?

There is evidence

This scenario, or something similar, though frequently rehearsed around here, is of course entirely unhelpful. Let's begin with the basics. Scientists make theories. These theories are sometimes very successful, and here we'll define success in terms of yielding explanation, prediction, and control: a successful theory is one that (in varying degrees) explains, makes accurate predictions, and thereby admits the possibility of some measure of intervention and control over nature in the form of technology.

But are successful theories true? Or even approximately so? First we must recognize that this is a quite different question from that of a theory's success. Talk of a theory's "truth" beckons us to enter the domain of scientific realism.

Theories often contain unobservable entities: forces, fields, genes, quarks, spacetime, electrons, etc. Now, scientific realism means many things to many people, so here we'll limit the discussion to "entity realism", that is to say, do these entities postulated by scientists in their theories actually exist? Do they "refer" to objects out there in the real world?

This question is perhaps rather baffling to many. The fellow in the street who has never given the matter much thought is inclined to believe, I suppose, that OF COURSE quarks and all their invisible cousins exist. How could it be otherwise?

Well, consider for example the case of the economist whose theory contains mention of "the average American taxpayer". The economist is surely not committed to the existence of such an entity. It's what we might call a useful fiction. The entity does not "refer"; it corresponds to nothing in the real world.

What, then, is the proper attitude we should adopt to the unobservable entities posited by scientists in their theories? Belief? Acceptance? Skepticism? Agnosticism?
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CoIin
CoIin: The principal argument for scientific realism is the so-called "Miracle Argument" which holds roughly that it would be a miracle if science had achieved the success it has without at least many of its best theories being true, or at least approximately true. You might be surprised to learn that this argument is actually quite hard to defend.

The two main weapons in the anti-realist's arsenal are the "pessimistic meta-induction" argument, and the argument from underdetermination of theories by evidence. (And I hasten to add that anti-realist does not mean anti-science. No death threats, please )

The former demonstrates, from an examination of scientific history, that a theory's containing entities that "refer" is neither a necessary nor a sufficient condition for success. Many theories containing entities which DO exist (as far we now believe) have been spectacularly unsuccessful. Conversely, many successful theories contained entities which we now believe do not exist, i.e. they refer to nothing at all. Through a process of induction we infer that our presently successful theories are likely to fare no better. And that means YOU, Mr Quark

The latter is conceptual rather than historical. Simply put, a body of evidence never ENTAILS a particular theory, by which I mean, the evidence may be a logical consequence of the theory, but a theory is never a logical consequence of the evidence. A multitude of theories are compatible with any body of evidence or data. (Just as an infinite number of curves can be found to fit any set of points). If an infinite number of theories are compatible with any given data set, then the "miracle argument" is turned on its head: it would be something of a miracle if, from an infinity of alternative mutually-incompatible theories, scientists had hit on the true one.

Before we move on, I'll leave you to ruminate over J. C. Maxwell's sanguine assertion that the luminiferous ether is the most highly confirmed entity in all science.

Well, as we all know, the ether turned out to be...um, ethereal (sorry ). But if we can't be confident of the ether's existence, what CAN we be confident of?

All positive contributions are welcome. Argue for any position you like. Just keep it polite, please.
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CoIin
CoIin: "The ephemeral nature of scientific theories takes by surprise the man of the world. Their brief period of prosperity ended, he sees them abandoned one after the other; he sees ruins piled upon ruins; he predicts that the theories in fashion today will in a short time succumb in their turn, and he concludes that they are absolutely in vain. This is what he calls the bankrupcy of science."

- Henri Poincare (psst, it's not that bad, he says more... )



The traditional picture of scientific knowledge has been one of cumulative growth: later scientists build upon or improve on the work of earlier scientists; theories may come and go but the general trend is "truth-tropic", that is, inexorably approaching truth.

A pretty picture indeed. And one that is perpetuated, much to our detriment I fear, in simplistic textbooks which trumpet victories but conceal defeats, as well as meretricious Discovery Channel showcases. An unrealistic or exaggerated representation of the scientific enterprise, I believe, is liable to cause more harm than good. Leave the preposterous truth claims to the less rational among us in other Forums on this fine website, I say. The utopian notion of steady cumulative progress is exposed as untenable by a study of revolutions in science; losses are incurred as well as gains; large chunks of theoretical knowledge are ditched wholesale on a regular basis.

But surely SOMETHING is retained through each instance of a scientific revolution? If newer theories oust older theories with nothing held over then scientific realism is surely in dire straits, and science can no more be approaching truth than successive waves in art or architecture.

This is, of course, the crux of the issue, and as you might imagine a lot of people are extremely anxious to demonstrate that indeed something IS retained through even the most radical of theoretical upheavals. What that something IS, if anything at all, is unlikely to be the entities posited within the theories, which is our topic at hand in this thread.

The realist wants to say that scientific theories successively approach truth. She wants to say that we don't just kick out the old and usher in a completely unfamiliar newcomer; rather, one REDUCES to the other, or one is a LIMITING CASE of the other. We hear this most commonly applied to the supplantation of Newtonian mechanics with Einsteinian relativity.

As long as we stick to mathematical equations, the idea of a limiting case is quite well defined, I think. It's a lot less clear, however, what it could possibly mean to say that a certain ENTITY is a limiting case of another. We might charitably grant, I suppose, that a tadpole is a limiting case of a frog, or even an asteroid is a limiting case of a planet, but to claim that an infinite and uniform space is a limiting case of a finite and non-uniform spacetime, or that invariant mass is a limiting case of variant mass, or that an attractive action-at-a-distance force is a limiting case of spacetime curvature, well...would take a braver, and I daresay more desperate, man than myself.

We should also remind ourselves at this point that most scientific theories are not merely a set of equations devoid of metaphysical assumptions. Newton's dynamics, for example, is an entire ontological package consisting of space,time, force, and so forth, providing the non-observable metaphysical architecture and furniture within which his equations yield predictions at the level of observation.

Which brings us to optics, a particularly damaging example for the proponent of trans-theoretical entity retention. Newton's optics postulated light as corpuscular - particles with mass which travel through a vacuum. This was later replaced in the 19th century by light construed as a wave of one kind or another propagating through the luminiferous ether, and currently we have light interpreted as massless photons which exhibit quantum effects.

Surely not even the most determined of scientific realists would argue that a corpuscle is a limiting case of a wave? Or that a wave is a limiting case of a photon? And if she DID, I might consider returning to the Religion Forum where the cheery if rather liberal interpreters will tell me that Jesus being crucified on the Passover in one gospel and on the Passover eve in another is NOT a contradiction.

Well, then, perhaps something IS retained through theory changes in science, and if there is, then the realist had better identify it, but that's a debate for another day. Whatever it is, though, it does not appear to be entities.

And so back to our old friend, Mr Quark. I suggest you squeeze him tight while you can because he might not be with us for long. And hey, isn't that good advice for living anyway?

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CoIin
CoIin: Well, how about you? Are you a realist? Who's the weirdo here anyway?

A Christian fundamentalist believes, more or less, that every word in the Bible is literally true. This leaves him in the unenviable position of having to defend talking snakes and a six-day creation account.

A scientific realist believes, more or less, that scientific theories are literally true. This leaves her in the unenviable position of having to defend Hilbert spaces (whatever THEY are ), perfect gases, inertial systems, and ideal incompressible fluids in steady flow in uniform gravitational fields.

Brian Ellis observes, "I should think that many space-time and quantum physicists would be quite puzzled by the suggestion that the theories they accept, and work with, might literally be true, since they have no clear conception at all of the reality with which these theories might correspond."

Yoo-hoo! Are you still an uncompromising, unapologetic realist?


Churchill: Madam, would you sleep with me for five million pounds?
Socialite: My goodness, Mr. Churchill… Well, I suppose… we would have to discuss terms, of course…
Churchill: Would you sleep with me for five pounds?
Socialite: Mr. Churchill, what kind of woman do you think I am?!
Churchill: Madam, we’ve already established that. Now we are haggling about the price.

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Bourbaki
Bourbaki: This is problematic from the get-go since you have not defined what you mean by 'real', 'real world', or 'observable'. Before anything else you should clarify exactly what you mean by these terms. I also think you'll find it essentially impossible to define 'real' in the way you think of intuitively. Due to this vagueness I find it very difficult to meaningfully discuss these ideas.


Here are some things you said that I want to address:

"Theories often contain unobservable entities: forces, fields, genes, quarks, spacetime, electrons, etc."
This is an example of a statement that heavily depends on what you define as 'observable'; While most people agree you cannot "directly observe" fields, many would say most (non-gravitational) forces we encounter daily ARE observable. There's no need to go as far as forces fields and spacetime - nobody can see the wind and yet nobody doubts its existence. Belief of existence is often due to inference.

"[...]many successful theories contained entities which we now believe do not exist, i.e. they refer to nothing at all."
By "do not exist" I assume you mean "are not real" (taking that intuitively). Surely you'll agree this is very different than nothing. Do numbers exist? Numbers are certainly not "real" objects, and equally obviously, the idea of numbers exists (and has been exceedingly fruitful). The vagueness kills everything.

"A multitude of theories are compatible with any body of evidence or data. (Just as an infinite number of curves can be found to fit any set of points)."
This is a great point - scientific theories are often interpolations of empirical data. It is not, however, true that physicists really have deal with infinitely many choices. An obvious example of intuition with curves is giving over ten points on the parameter of a circle. Just as given enough data there are intuitive ways to obtain curves from sets of points via interpolation, there are more and less relevant models which can account for observations while maintaining mathematical consistency and consistency with the laws of nature that hold nearly axiomatic status (like conservation laws). For instance, when we look at a ball flying through the air, our brain does not really process the entire continuum of its trajectory (which may not even be a real continuum since real numbers are a pure abstraction), it samples discrete frames of the ball's position, and yet, I've never met anyone who believes that in "reality", the ball only appears to have a continuous trajectory but in fact, for tiny periods of time, turns into a cucumber, even though such theories are not too difficult to formulate using higher mathematics.

Poincare was one of the greatest mathematicians. As such he was able to recognize how naturally simple, intuitive, concepts may often be generalized to far-reaching and more complicated notions. People being people, our observational skills increase with time often unraveling discrepancies in our initial, intuitive models and (because this is science) immediately rule them all out. I think he saw science in this constant state of just waiting for counter-evidence which would in turn require mathematical formulation to evolve so as to encompass all the evidence.

"As long as we stick to mathematical equations, the idea of a limiting case is quite well defined, I think. It's a lot less clear, however, what it could possibly mean to say that a certain ENTITY is a limiting case of another."
This is also a very interesting topic. Again, before I say what I think I must stress that 'entity' is undefined, so maybe what I will treat as an entity will not coincide with what you think. I'd like try and get my point across with an example with is highly analogous to what's going on between space and spacetime. I implore you to read it thoroughly because it's really very analogous.
Suppose you have a trampoline with uniform tension (just a flat trampoline). Its surface is planar. Now suppose you start arranging objects with small mass on its surface - few enough and each light enough for the surface to deform only slightly. The surface is no longer planar, but it's "almost planar". Great. Now suppose some smart ants lived on this trampoline but have never come near these objects (this is a very reasonable assumption for a big enough trampoline), where by 'near' I mean close enough to notice the curvature of the trampoline's surface. Their physics would probably be set in a planar universe, and their geometry would likely be euclidean. Now suppose they're finally in proximity to one of these objects. The ants would perform simple experiments which would blatantly refute their physics! Here's an outline of such an experiment: three ants take a meter stick with two stretching it at the endpoints and one just holding it at the middle. They do this far away from the object and slowly start approaching it (the curvature increases). They would find that the closer you get to the object, the more distance the meter stick would show. In their world this cannot happen, but we know it's just because the middle ant is "sinking" and pulling the meter stick down. If they're lucky, they have an Einstein ant that would tell them their universe is not really planar at all - it's actually a 3D surface! Antenstein would then formulate General Relantivity but despite his great accomplishment, antgineers wouldn't want to use his complicated formulas! Why should they? Everything they've done thus far has worked!
Why has their incorrect physics been hitherto reliable? Because far away from the objects, the trampoline is "almost planar"! It is a limiting case of the "real world" which is a 3D surface, but often a damn good one! In this example a naive conception of the whole universe is a limiting case of a more sophisticated one.

I'm tired so great big portions of this post will probably be unclear and unpleasant to read but oh well...
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CoIin
CoIin: Bourbaki. Glad to have you aboard. Your analysis is astute and insightful as ever. Due to limitations of time and, in some cases insufficient knowledge, I can't address everything you've raised, much as I'd like to, though you can rest assured I've studied your post assiduously. Apologies in advance if I miss anything or if I've misunderstood.

First of all, I'll try to make my motivation more clear. This thread is partly a reaction to a long-standing distaste I feel observing one or other Wireclub member admonishing another over how ridiculous his beliefs are, when it seems to me at least he might be more profitably employed examining the robustness of his own. It's my experience that those who make the most noise about "Truth" (whatever the heck that is) are those who have given the matter the least thought. It's not obvious to me that the quark-believer, doubtless having never examined the matter, is in any position to ridicule the God-believer or the alien enthusiast. And even if he were, he might opt for gracious forbearance instead.

I'd hate to get bogged down in a battle of definitions, and I'm not particularly competent to do so in any case . I'm using the terms you listed as they are used by others, although the usage undoubtedly varies from person to person. A few words about "real", "real world" and "observable" first though, as per request.

The "real world", to the realist, JUST IS the description of the world that science gives us. It would be reasonable to assume, I think, that most scientists, and most of the rest of us (by default - i.e. having never considered the alternatives), subscribe to the correspondence theory of truth; viz., the rather prosaic sounding "a statement such as 'snow is white' is true if and only if it is a fact that snow is white" . On this view, an entity is real if it "corresponds" or "refers", that is, the entity has a mind-independent ontology. Snow and quarks are held to be real insofar as they correspond to entities in the real world whose existence is irrelevant to what we humans happen to think of them.

Now, with an entity like snow, or the Sun, which is defined ostensively (we can point at it), reference is not a problem. What science tells us about the nature of the Sun may, and indeed HAS, changed quite dramatically, but there has never never been any doubt vis-a-vis reference. "It's still that big yellow thing up there!". The situation with unobservables like atoms, say, is more problematic. When one model of the atom is replaced by another, we don't have the option of pointing and saying "Yeah, but we're still talking about THAT!". The meaning of the term "atom" is determined entirely by its use in scientific theories, and if the theory changes...well, what do we say now? It seems we have to face the unpleasant conclusion that either reality has changed (we have changed what atoms are ) or else that the entities in the old theory referred to nothing at all.

With regards the ontological status of numbers (do numbers refer?), I haven't done any reading on this specifically (how about you?), but I've seen hints that surprisingly many mathematicians, scientists, and philosophers DO maintain the objective existence of numbers, presumably in some ethereal Platonic realm of ideas that perhaps only Aegean Airlines flies to.

(From the little reading I've done on the topic, Quine apparently grants the same ontological status to mathematical classes as he does to the objects of physics. Don't ask me to explain why, please . Oh, and by the way, your man Tarski has a lot to say about truth too. Don't ask me to explain that either )

Well spotted, Bourbaki! You're not the first person to point out that the observable/unobservable distinction is rather nebulous. Various philosophers have drawn it in different ways; others deny it altogether. Clearly, what is observable to hawk-eyed you (a distant bird or a speck of dust) may be unobservable to myopic me . Some discriminate between that which is practically unobservable (dinosaurs) and that which is unobservable even in principle (a magnetic field? ). One person might claim electrons are observable; another that they are "detected" or "inferred" and not "observed". Some hold that observation through instrumentation does not constitute direct observation, but where do we draw the line? - eyeglasses? Or an electron microscope? Pinky might insist genes are observable, Perky might demur. It goes on... (I seem to recall Carl Hempel's quaint example of the far side of the Moon as an unobservable. Times change, eh? )

Quite possibly there is no clear-cut distinction, only a continuum with tables and chairs at one end, while at the other end... well, quarks, I suppose. How serendipitous!

(And, of course, many philosophers will deny that we directly observe tables and chairs; all we have direct access to is "sense data". I'd stick with mathematics if I were you, friend )

Finally for now, otherwise I'll go on all day , your invocation of spacetime geometry provides us with a superb and real life example-in-action of the thesis of "underdetermination of theories by evidence", which as I noted in my opening post is the second big gun militating against scientific realism (and about which your bon ami, Poincare, waxed lyrically).

You noticed yourself ( "It is not, however, true that physicists really have deal with infinitely many choices." ) that underdermination till now has been mainly a conceptual worry. What we find in real-life science is generally the opposite; rather than being inundated with a proliferation of mutually-inconsistent but empirically equivalent theories, the problem for scientists tends to be coming up with just ONE theory that fits the data!

Having said that, Einstein posits a non-Euclidean spacetime structure for a relativistic universe. This theory, so the story goes, is empirically indistinguishable from a similar theory which postulates Euclidean geometry PLUS forces which shrink meter sticks and slow down clocks under certain conditions. The situation here, then, is not that more evidence will settle the matter as it becomes available; instead the two logically-incompatible theories are identical in ALL their observational predictions; they cannot be distinguished on the basis of evidence alone.

These two rival theories, then, are strongly underdetermined. It's no use looking to "evidence", if by that you mean empirical evidence, for all evidence for one is necessarily evidence for the other.

It's interesting here to compare the views of two towering figures in 20th century philosophy of science: Rudolf Carnap and W.V.O. Quine, two men I greatly admire and whose positions I'll try to sketch without, I hope, doing too much violence to their thought.

Carnap, a positivist and conventionalist who I daresay speaks for many anti-realists, would hold that there is no "fact of the matter" as to which of the two rival theories is true, and to enquire thereinto is to ask a meaningless question. Remember Wittgenstein's famous "Whereof we cannot speak; thereof we must remain silent"? The Logical Positivist criterion of meaning was verifiability; if a statement can't (at least in principle) be verified, it is literally meaningless.

Anti-realism might strike some as an anti-science position. I would suggest precisely the opposite. If we begin making claims into the "true" geometric structure of space - Euclidean vs nonEuclidean - claims WHICH CANNOT BE VERIFIED EMPIRICALLY, then we are epistemically no more worthy of respect than the Christian who makes empirically unverifiable doctrinal claims, or the German erectors (whose names all begin with H) of grandiose metaphysical systems, systems which tend to inspire fits of giggles in hard-nosed scientists. It was revulsion AGAINST this "the nothing itself nothings" Heidegger metaphysical silliness and admiration FOR the empirical success of relativity theory that induced the Positivists to react.

For Carnap, then, the geometry of the universe is purely a matter of pragmatics, not reality. Simple is better, not truer. "Space is Euclidean" is neither true nor false. It's a pseudo-question.

Quine, speaking for many realists, I think, would concede that the matter does not admit of empirical confirmation (evidence ain't gonna hack it, baby), but would insist on a "fact of the matter", and that we can still be guided toward truth by non-evidentiary factors. We should appeal perhaps to "Inference to the Best Explanation" (IBE) which, on the realist account, licences us to infer FROM an explanation being the loveliest (i.e. from non-evidentiary considerations such as simplicity) TO its truth.

(Likewise for someone like Popper who rejects induction altogether, there IS a fact of the matter - space is either Euclidean or not - but on KP's account, we'll never know which.)

And this brings us neatly back to the original argument for scientific realism - the "miracle argument" - which is itself a form of meta-IBE : the best explanation for the success of science, the realist asserts, is that our best theories are true, or approximately so. We may therefore infer with justification to the truth of this conclusion.

The problem here, then, is that an argument which is only recognized as valid by the realist in the first place is being invoked (at the meta-level) to provide a justification for scientific realism itself.

Thanks for the input, Bourbaki. I'm no doubt confused over much of what I've said above. That's why we're here, eh?
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CoIin
CoIin: A quick word on the curve-fitting problem...

The analogy between the curve-fitting problem and the issue of underdetermination in science is good as far as it goes, but can be a bit misleading too, I'm afraid. (I think your cucumber concern, Bourbaki, reflects this misapprehension.)

Suppose our "evidence" is 1000 points on a graph. The points are such that a single straight line can connect them all. We do exactly this and announce the discovery of a new theory or law. Then, an annoying pedant (a philosopher, no doubt ) points out that although these 1000 points can indeed be connected by a pretty straight line, they can also be connected by an indefinite number of alternative, much less attractive curves.

We concede that the pedant's point is logically or mathematically correct, but suggest that he go take a long walk along a short pier; the conclusion to be drawn is quite obvious, thank you very much.

This scenario is misleading when applied to science, I think. Things are rarely so pretty in the real world that one single straight line can unify the evidence. Evidence for a scientific theory tends to be wildly heterogeneous.

A better analogy would be with a set of scattered data through which no pretty straight line or simple curve can be drawn. A brilliant scientific theoretical discovery would be analogous to the discovery of a complex curve which fits the data. Meanwhile, though, the concern that the thesis of underdetermination raises is that multiple (and equally complex) curves can be drawn through the same data.

For the anti-realist, "truth" is irrelevant: it's a pseudo-question; one curve is as good as another. If we do choose one over the alternatives, it will be due to pragmatic reasons.

For the realist on the other hand, many curves may fit the data, but they cannot all be TRUE. Only one can.

The other misleading dimension of the curve fitting analogy is that it suggests a scientific theory accommodates ALL the data. This is never the case with any interesting (i.e. non-trivial) scientific theory.

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CoIin
CoIin: The realist defending the position that scientific theories converge on the truth is apparently fighting a losing battle, at least if the entities or objects posited within theories constitute his footsoldiers. There is scant evidence to suggest that science is converging upon the correct furniture of the universe.

"Well, then", the spirited realist might affirm, "Science does converge upon the truth. You just don't see it. If you've got a problem with entities, I think you'll find that newer theories tend to preserve the important mechanisms, models, and laws of earlier theories."

Once again, though, the history of science tells a different story. Philosopher Larry Laudan elaborates:-

"So construed, the claim is patently false. Copernican astronomy did not retain all the key mechanisms of Ptolemaic astronomy (e.g. motion along an equant); Newton's physics did not retain all (or even most of) the theoretical laws of Cartesian mechanics, astronomy and optics; Franklin's electrical theory did not contain its predecessor (J. A. Nollet's) as a limiting case. Relativistic mechanics did not retain the ether, nor the mechanisms associated with it; statistical mechanics does not incorporate all the mechanisms of thermodynamics; modern genetics does not have Darwinian pangenesis as a limiting case; the wave theory of light did not appropriate the mechanisms of corpuscular optics; modern embryology incorporates few of the mechanisms prominent in classical embryological theory. As I have shown elsewhere (Laudan 1976), loss occurs at virtually every level; the confirmed predictions of earlier theories are sometimes not explained by later ones; even the 'observable' laws explained by earlier theories are not always retained, not even as limiting cases; theoretical processes and mechanisms of earlier theories are, as frequently as not, treated as flotsam."


At this juncture, or at any juncture, the less scrupulous adversary does, of course, have the option of rendering himself invulnerable to criticism by adopting any one of various dastardly 'goal-post-moving' or 'no-true-Scotsman' tactics. He might, for example, ejaculate, "Aha! That doesn't count! These examples you gave of theories containing entities that don't refer were all immature sciences. The entities in a mature science always refer."

And with a sense of foreboding, I enquire, "And how am I to know what a mature science is?"

"A mature science is one that...

The soporific tones of my interlocutor act as a lullaby, inducing me to reminisce over yesterday's polemics in the Religion Forum... "Please tell me why this contradiction that I found in the Bible fails to refute your claim that there are no contradictions in the Bible?"

: Because the Bible is an internally consistent work. The word of God can contain no contradictions. You just don't see it.

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CoIin
CoIin: Larry Laudan exposes misconceptions about the idea of a "limiting case"...


"There is a deep reason why the convergent realist is wrong about these matters [cumulationist or retentionist construals of science]. It has to do, in part, with the role of ontological frameworks in science and with the nature of limiting case relations. As scientists use the term 'limiting case', T1 can be a limiting case of T2 only if (a) all the variables (observable and theoretical) assigned a value in T1 are assigned a value by T2 and (b) the values assigned to every variable of T1 are the same as, or very close to, the values T2 assigns to the corresponding variable when certain initial and boundary conditions -consistent with T2 *** (see below) - are specified. This seems to require that T1 can be a limiting case of T2 only if all the entities postulated by T1 occur in the ontology of T2. Whenever there is a change of ontology accompanying a theory transition such that T2 (when conjoined with suitable initial and boundary conditions) fails to capture T1's ontology, then T1 cannot be a limiting case of T2. Even where the ontologies of T1 and T2 overlap appropriately (i.e., where T2's ontology embraces all of T1's), T1 is a limiting case of T2 only if all the laws of T1 can be derived from T2, given appropriate limiting conditions. It is important to stress that both these conditions (among others) must be satisfied before one theory can be a limiting case of another. Where 'closet positivists' might be content with capturing only the formal mathematical relations or only the observable consequences of T1 within a successor, T2, any genuine realist must insist that T1's underlying ontology is preserved in T2's, for it is that ontology above all which he alleges to be approximately true."

{Colin's note : Attention all you "closet positivists" . Whenever you back away from a position of "the theory is true" to one of "the equations work - they got us to the Moon", be aware of the radical shift thus incurred: whether you recognize it or not, you renounce realism and embrace anti-realism.}

"Too often, philosophers (and physicists) infer the existence of a limiting case relation between T1 and T2 on substantially less than this. For instance, many writers have claimed one theory to be a limiting case of another when only some, but not all, of the laws of the former are 'derivable' from the latter. In other cases, one theory has been said to be a limiting case of a successor when the mathematical laws of the former find homologies in the latter but where the former's ontology is not fully extractable from the latter's."

"Consider one prominent example which has often been misdescribed, namely, the transition from the classical aether theory to relativistic and quantum mechanics. It can, of course, be shown that some 'laws' of classical mechanics are limiting cases of relativistic mechanics. But there are other laws and general assertions made by the classical theory (e.g., claims about the density and fine structure of the aether, general laws about the character of the interaction between aether and matter, models and mechanisms detailing the compressibility of the aether) which could not conceivably be limiting cases of modem mechanics. The reason is a simple one: a theory cannot assign values to a variable which does not occur in that theory's language (or, more colloquially, it cannot assign properties to entities whose existence it does not countenance). Classical aether physics contained a number of postulated mechanisms for dealing inter alia with the transmission of light through the aether. Such mechanisms could not possibly appear in a successor theory like the special theory of relativity which denies the very existence of an aetherial medium and which accomplishes the explanatory tasks performed by the aether via very different mechanisms."


*** above {This matter of limiting conditions consistent with the 'reducing' theory is curious. Some of the best-known expositions of limiting case relations depend (as Krajewski has observed) upon showing an earlier theory to be a limiting case of a later theory only by adopting limiting assumptions explicitly denied by the later theory. For instance, several standard textbook discussions present (a portion of) classical mechanics as a limiting case of special relativity, provided c approaches infinity. But special relativity is committed to the claim that c is a constant. Is there not something suspicious about a 'derivation' of T1 from a T2 which essentially involves an assumption inconsistent with T2? If T2 is correct, then it forbids the adoption of a premise commonly used to derive T1 as a limiting case. (It should be noted that most such proofs can be re-formulated unobjectionably, e.g., in the relativity case, by letting v --> 0 rather than c --> oo.) }


Read Laudan's entire paper online:-

http://philoscience.unibe.ch/documents/TexteFS11/Laudan1981.pdf

London's calling to the anti-realist
Come out of the cupboard you boys and girls



And don't look to us
If phony convergent realism has bitten the dust
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CoIin
CoIin: Oh, and just in case a certain friend happens to be reading...

"Nowhere has the realist established - except by FIAT - that non-realist epistemologists lack the resources to explain the success of science."

- ibid

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cowpoker
cowpoker: LOL ...yes I AM reading, and you just ruined a perfect 34-year streak.
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CoIin
CoIin: 34 years of not reading my oeuvre?
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cowpoker
cowpoker: No, I only had 32 years of that.
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cowpoker
cowpoker: It was a good run while it lasted, though.
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PuppYofDoom
PuppYofDoom: In short its like saying your genitals do not exist. The idea of your genitals being real and arguments for it can be swept away using your framework pleonasm.
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CoIin
CoIin: Hmm, I don't think the analogy works. Personally speaking, at least, unlike quarks my genitalia are observable. On a good day
(Edited by CoIin)
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CoIin
CoIin: The first argument against scientific realism, namely, the Pessimistic Induction (or Pessimistic Meta-Induction), is not hard to understand. It is a matter of incontrovertible historical FACT that scientists have in the past posited the existence of unobservable entities (that means things like quarks, not human genitalia ) which they later disowned. And this is by no means rare; it has happened time and time again.

The argument does not, of course, establish the non-existence of quarks, nevertheless, confronted with such evidence, the dogmatic insistence that quarks DO exist seems to me a highly irrational position. Indeed we might describe it as an article of faith. We also see reflected here, I believe, the puzzling refusal of a certain kind of person to even ENTERTAIN the possibility that what they've read in (what they take to be) "respectable sources" could be erroneous or misleading.

It's the same mindset which seems quite incapable of appraising an argument on its own merits: the very same argument they would dismiss as nonsense on Wireclub would be taken as gospel truth if delivered from the mouth of, say, Richard Dawkins, Carl Sagan, or Penn and Teller (whoever the heck THEY are, but I see vids plastered everywhere. They seem to be admired as gurus. From the little I've seen, though, I'm quite underwhelmed by their powers of analytical thinking ).

What follows is a far from exhaustive list of obsolete, but successful and well confirmed scientific theories which contained unoberservable entities which, as far as we can tell from our present day vantage point, do not exist, i.e. they refer to nothing at all. The most damning cases of all - optics and Newtonian physics - have already been discussed above. The myriad models of the atom to have come and gone are also excluded.


- the crystalline spheres of ancient and medieval astronomy
- the humoral theory of medicine
- the effluvial theory of static electricity
- 'catastrophist' geology, with its commitment to a universal (Noachian) deluge
- the phlogiston theory of chemistry
- the caloric theory of heat;
- the vibratory theory of heat;
- the vital force theories of physiology;
- the electromagnetic aether;
- the optical aether;
- the theory of circular inertia;
- theories of spontaneous generation


Laudan again... "This list, which could be extended ad nauseam, involves in every case a theory which was once successful and well confirmed, but which contained central terms which (we now believe) were non-referring. Anyone who imagines that the theories which have been successful in the history of science have also been, with respect to their central concepts, genuinely referring theories has studied only the more 'whiggish' versions of the history of science (i.e., the ones which recount only those past theories which are referentially similar to currently prevailing ones)."

(Edited by CoIin)
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CoIin
CoIin: The popular image of science as an enterprise that "gets at the truth" is fundamentally mistaken.

This revelation is bound to be disturbing to many. It needn't be. Science DOES progress, science IS cumulative, but the progress and accumulation transpires at the level of the practical - knowledge of what we can DO rather than knowledge of how the world or universe REALLY IS. Few would deny that we "anticipate" nature better than before; the growing power of science at the level of prediction and control is patent. The claim that science progressively approaches ultimate truth, by contrast, is quite unsustainable.

An analogy might help. On the island of Blork there is one judge, Judge Jones. Over the past decades many citizens of Blork have been, and continue to be, convicted and sentenced to prison terms by Judge Jones. The vast majority of citizens ever sentenced by the judge were subsequently found to be innocent and released with an official pardon. Many others remain behind bars, although their numbers pale in comparison to those already acquitted.

Now then, what are we to say of Judge Jones? Should be describe him as a judge who "always gets the right man". Certainly not! - nothing could be more preposterous. And what of the guilt of these prisoners still behind bars? Well, inasmuch as there has been no apparent change in the judge or his judicial practices, the rational inference to draw is that it's just a matter of time until they also win an acquittal.

Meanwhile, everyone, or almost everyone, agrees that Judge Jones has been good for the island - crime rates have dropped and the quality of life has risen.

Like it or not, this IS the reality of science. The overwhelming majority of theories ever held to be true were later abandoned, thus it seems probable that our current theories will meet the same fate. And before you get in a flurry, no, the position I'm espousing here is not a crank position. Many scholars already know, recognize, and accept this. These things just take a while to trickle down to society as a whole. The mistake here would be to think that this is a criticism or a defect of science, or that we are irrational in our pursuit of it. Quite the contrary (it's a feature, not a bug ). It is the traditional picture of science which is profoundly wrong and any irrationality lies in the expectation of science to yield "true" theories.




"If there is one thing we can learn from the history of science, it is that the scientific theorizing of one day is looked on by that of the next as flawed and deficient. The clearest induction from the history of science is that science is always mistaken - that at EVERY stage of its development, its practitioners, looking backward with the wisdom of hindsight, will view the work of their predecessors as seriously deficient and their theories as fundamentally mistaken. And if we adopt (as in candor we must) the modest view that we ourselves and our contemporaries do not occupy a privileged position in this respect, then we have no reasonable alternative but to suppose that much or all of what we ourselves vaunt as "scientific knowledge" is itself presumably wrong."

- Nicholas Rescher


"For in formulating the question as to how to explain why the methods of science lead to instrumental success, the realist has seriously misstated the explanandum. Overwhelmingly, the results of the conscientious pursuit of scientific enquiry are failures: failed theories, failed hypotheses, failed conjectures, inaccurate measurements, inaccurate estimations of parameters, fallacious causal inferences, and so forth. If explanations are appropriate here, then what requires explaining is why the very same methods produce an overwhelming background of failures and, occasionally, also a pattern of successes. The realist literature has not yet begun to address this question, much less to offer even a hint of how to answer it."

- Arthur Fine
(Edited by CoIin)
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CoIin
CoIin: Attention all science fans

Have you ever felt frustrated before in trying to communicate with someone who is misusing a scientific term, you know, perhaps a word like "energy". These annoying New Age types are liable to say things like "all thought is energy" (or whatever. The specifics are unimportant). Any sensible scientist will tell you this is NOT what energy means, thank you very much!

Well, this IS precisely the problem of "incommensurability", first adverted to by the likes of Kuhn and Feyerabend, and about which I've written in other places. If two people are using the same term, but in a different way, then a partial or complete breakdown in communication ensues.

Just another silly philosopher's fancy? The bruises on your forehead say otherwise, dude.

"Yeah, but if only these people could learn to use their terms properly we might make some progress - like we do in science. We might actually be able to discern who's right and who's wrong."

Indeed you might. But rest easy, you're not alone. Newton and Einstein and others have been through it all too. Now, if only Einstein could learn to use a term like "mass" the way it's meant to be used (i.e. an invariant property) we might actually be able to sensibly compare the two theories. And things get even worse when you consider "space" and "time" which don't even exist for AE

So unless all involved can agree on what relevant terms mean - and, more fundamentally, what things exist at all! - don't expect to make much progress on the march towards Truth.
(Edited by CoIin)
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Bourbaki
Bourbaki: "If two people are using the same term, but in a different way, then a partial or complete breakdown in communication ensues."

I think this sums up perhaps one of the greatest problems present in philosophy and absent from exact sciences. Since philosophers refrain from rigorous definitions and use natural language they are especially vulnerable to these mis-communications and in general to vagueness.
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CoIin
CoIin: Bourbaki

I think what you say is largely true, but also uncontentious. I don't think I've ever heard the claim made that philosophers all speak the same language, or that philosophy is a cumulative enterprise.

The problem of incommensurability between theories or between paradigms is problematic only insofar as science is construed as being epistemically cumulative; new theories build on or improve on old theories, according to the traditional picture at least, and on this optimistic account, we move inexorably closer to truth.

Philosophers have little compunction in dismissing their predecessors, "Descartes/Leibniz/Kant/etc may have been a genius but he was just plain WRONG." Scientists tend to be much more reluctant to make such bold pronouncements. (Although I believe they should. The result is rampant confusion. Is gravity a force or not? )

The problem incommensurability raises for science, then, is that if an old theory P and a new theory Q contain common terms but which differ in meaning ("mass" in Newtonian dynamics and Einsteinian dynamics are not the same beast), or if one contains terms which the other doesn't even recognize, it becomes very difficult to argue that Q is a continuation of, or an improvement on P.

It's hard to see how we could be approaching truth if the subject keeps changing!
(Edited by CoIin)
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CoIin
CoIin: Hi again, Bourbaki

Your last post set me thinking, and upon further reflection I'd be inclined to suggest that in many cases the opposite obtains - it is, as a matter of course, philosophers who seek to add logical justification, clarity, and rigor to ill-defined concepts which scientists are prone to use rather haphazardly.

You'll get an inkling of this from my thread on the Scientific Method. Scientists tend to have only the vaguest notion of what this might be. My whole thread is devoted to the attempts of philosophers to be more specific: is there such a thing? Can it be codified or even articulated at all? Is there, or could there be, an "algorithm" of the Scientific Method?

And the problems exposed in the process turn out to be immense, if not altogether insurmountable. Scientists, meanwhile, continue their work in blissful insouciance at a more intuitive and common sense level.

I thought I might here draw your attention to another example, one that your sharp logical mind will surely appreciate. Science devotees, and even scientists themselves, are wont to proclaim rather carelessly "Theory X is highly confirmed."

Probe further and you're likely to be met with much embarrassment and mumbling. Well, this IS the kind of thing that logicians and philosophers attempt to clarify. What exactly does it mean to say that a theory is "confirmed", never mind highly confirmed?

Check out the marvellous "Raven Paradox" and more...

Topic: Science

.
(Edited by CoIin)
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CoIin
CoIin: P.S. It also struck me in your post, Bourbaki, that when most people think of philosophy, it seems they think of metaphysics. They think of monstrous and absurd (to me anyway) projects of 19th century Germans to describe ultimate reality (whatever that is) from the comfort of their armchairs. They think of trees falling in forests and they think of the meaning of life.

In this, I share the exasperation implicit in your post.

Such matters hold little appeal to me. The kind of philosophy that interests me, however, is known as "analytic philosophy". It's rather vaguely defined ( ) - a bit like Science itself or the Scientific Method - but I think all would agree that it aims at, and is characterized by, clarity and rigour.

Within this tradition, my particular passion is the philosophy of science, which aims to ADD clarity to the scientific enterprise rather than confuddle it. I think you'd find it fascinating too.

You lament the imprecision of natural language. I do too. But SCIENTISTS use natural language; their theories are almost invariably presented in natural language. The philosophers of science have no option but to follow suit.

It would be very nice if, say, Darwin had presented his theory in concise deductive form. He didn't. He served up a lengthy narrative instead. It's left to the rest of us to interpret it.
(Edited by CoIin)
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CoIin
CoIin: This is a bit off topic, but who cares, eh?

Bourbaki bemoans the use of natural language and the lack of logical rigor in certain disciplines. I'm sure we can all sympathize, and you're not the first to complain, of course. The Logical Positivists felt exactly the same and attempted to rectify the situation, with regard science at least.

The LP's, comprising some of the smartest geeks you're likely to find anywhere, put together an interpretation of scientific theories known as the "Received View" which held sway in the philosophy of science for several decades until the walls began to crumble around the 1960's. For various reasons, some of which are expounded in my Scientific Method thread, the project just wasn't tenable. The reduction of science to mathematics and logic, alas, must take its place in the graveyard of nice ideas which "gang aft agley".

Very relevant to this thread, however, is the LP's treatment of theoretical or unobservable entities. Statements containing entities such as "the absolute", "life force", "entelechy", and "god" are dismissed as metaphysical nonsense (literally) insofar as they fail to meet the LP's verification criterion of meaning: no observation could ever bear on their truth or falsity. An entity like "quark" is acceptable, and thus scientific, as long as it is connected to experience (i.e. if you perform such-and-such, you will observe such-and-such). This leaves open the possibility for either a realist interpretation (quarks actually do exist) or an instrumentalist interpretation (quarks are a convenient fiction).

Here we go then... (and I don't claim to understand all of this ). All that follows is reproduced from "The Structure of Scientific Theories" by Frederick Suppe.


"We have seen the main features of the Received View as initially presented by the Vienna Circle. In essence that initial version of the Received View construed scientific theories as axiomatic theories formulated in a mathematical logic L meeting the following conditions:-

(i) The theory is formulated in a first-order mathematical logic with equality, L.

(ii) The nonlogical terms or constants of L are divided into three disjoint classes called vocabularies:
.......(a) The logical vocabulary consisting of logical constants (including mathematical terms).
.......(b) The observation vocabulary, Vo, containing observation terms.
.......(c) The theoretical vocabulary, Vt, containing theoretical terms.

(iii) The terms of Vo are interpreted as referring to directly observational physical objects or directly observable attributes of physical objects.

(iv) There is a set of theoretical postulates T whose only nonlogical terms are from Vt.

(v) The terms in Vt are given an explicit definition in terms of Vo by correspondence rules C - that is, for every term 'F' in Vt, there must be given a definition for it of the following form:
.................................................. (x)(Fx iff Ox)
where 'Ox' is an expression of L containing symbols only from Vo and possibly the logical vocabulary.


It is a corollary to this characterization that all theoretical terms are cognitively significant in the sense that they each satisfy the verification criterion of meaningfulness. The set of axioms T is the set of theoretical laws for the theory, and the set C of correspondence rules stipulates the allowable applications of the theory to phenomena; the theory is identified with the conjunction TC of T and C."
(Edited by CoIin)
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CoIin
CoIin: Can we have a new page please?

This PMT is killing me
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StarryStarryNight
StarryStarryNight: PMT? No idea what that means...I'm only familiar with PMS...
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