There Are No Quarks : Can You Prove Me Wrong? (Page 9)

CoIin: Yes, I acknowledge I said that. And I stand by it.

You'll have to explain for us where the dishonesty in this lies.

TheismIsUntenable: Don't be obtuse. Acknowledge that we have detected photons.

CoIin: No, This is our entire disagreement.

I acknowledge that you BELIEVE you have detected photons. And you may indeed be right.

But you may also be wrong.

Now, you still haven't explained how I've been dishonest. Please do so now.

TheismIsUntenable: I haven't detected any photons.

Am I to understand that you are rejecting the entire body of sources I provided to establish the detection of photons?

CoIin: I accept all your evidence as legitimate.

What I'm denying is the claim that photons exists CAN BE KNOWN WITH CERTAINTY. I submit anyone who advances such a claim is unjustified.

When can we expect this explanation from you about my dishonest behavior?

TheismIsUntenable: I'm not sure anything at all can be known for certain. All knowledge is epistemically contingent. Is that really all this has been about? The delusion of certainties?

CoIin: You said on page 7 : "What we have called photons exist."

You said on page 8 : "Until you've read the sources I provided for you (which make it impossible to say that photons do not exist) then you're just wasting your energy on a losing argument."


I have asked you time and time again - and you have evaded time and time again - whether it's possible that you (and other people) could be wrong about the existence of photons.

Are you ready to answer now?

And after that, I'd still like you to provide support for your accusations of my dishonesty. Thanks.

TheismIsUntenable: So your issue was with "which make it impossible to say that photons do not exist?"

If so, I'm sorry to inform you that this was hyperbolic.

CoIin: So you could be quite wrong about photons?

TheismIsUntenable: In the same way that I could be wrong about the existence of the moon. But beyond that, no.

CoIin: No, not in the same way at all. Your comments betray a fundamental misunderstanding of the thread, which is the division between SCIENTIFIC realism and antirealism.

The scientific antirealist does not dispute the existence of everyday macroscopic OBSERVABLE entities (like the Moon).

Can we agree that photons and quarks are not entities of this kind? They are unobservable, THEORETICAL entities.

To dispute the existence of the Moon, tables and chairs, and all the rest would take us into the realm of metaphysical antirealism. This thread ain't going there.

We tend not to be wrong about the existence of macroscopic observable entities (like rabbits or the Sun) because, as I described earlier in the thread, they are learned ostensively, i.e. we can point at them! Their reference is thereby FIXED. It may turn out that our knowledge of rabbits and the Moon is grossly in error, but their very existence is not threatened thereby - "It's still that thing over there. LOOK!"

It may turn out that rabbits are actually immensely sophisticated robots designed by superintelligent extraterrestrials, perhaps as part of a psychological experiment on us. But even supposing such an unlikely revelation came to light, they'd still be rabbits, would they not? It's unlikely we'd say "We used to believe in rabbits but now we don't. There is no such thing as a rabbit."

This is not the case with unobservable theoretical entities in science which, as a matter of historical fact, have a tendency to be ephemeral. Unlike observable entities, they have no fixed reference. It IS sometimes the case in science that unobservable theoretical entities - like the aether, phlogiston and perhaps photons - are initially taken to be real only to be abandoned later.


And you still haven't supported your accusations of my dishonesty.

TheismIsUntenable: "Your comments betray a fundamental misunderstanding of the thread"

I'm gonna presume English isn't your first language since this effectively says the opposite of what I think you're trying to say.

Photons are observed (by detection) just as all the other subatomic particles. Do you doubt the existence of carbon monoxide?

If you can cite a single relevant subatomic particle that has gone by the wayside in modern physics (e.g. since the advent of DNA) then you may have a case. Unfortunately you seem to be desperately grasping at straws...phlogiston (1600s), aether (1800s). Be serious, Colin.

CoIin: First, you're back to saying that photons have been "detected" and "observed". These are both success terms. To say you have detected photons is to presuppose their existence. You're arguing in a circle.

Now, don't misconstrue, Perhaps you HAVE really detected them, but you can't know that with certainty.

re carbon monoxide : Yes, we could be wrong about that too. I'm not saying it's LIKELY; but a possibility nonetheless. Are you, on the other hand, claiming that carbon monoxide is eternally epistemically secure?

( I'd remind you of your comment above : "All knowledge is epistemically contingent" )


re "If you can cite a single relevant subatomic particle that has gone by the wayside in modern physics (e.g. since the advent of DNA) then you may have a case."

No, I can't. Not off the cuff anyway. Perhaps there are no such examples.

But then I'd have to turn the question back at you. You seem to be implying these abandonments of theoretical entities is a thing of the past; it DOESN'T or CAN'T (which one? ) happen any more. Is this a correct representation of your position? If so, please explain how you know this.

Thanks!

And what of my dishonesty? Are you going to support your allegations or not?

TheismIsUntenable: I am not understanding you here. I mean, I could say the same thing about the moon. "I see it" means I presuppose it exists? WHAT? Please clarify, because the detection / observation is the confirmation of the existence.

You're sounding more and more like a christian fundamentalist here. I'm not sure if you're serious about carbon monoxide. Do you mean we can be wrong in the same sense as we can be wrong about the moon, or is this about "scientific antirealism?"

You're right, it's not a proper defense to say that recent science is improved. So I'll add that those ideas (aether, phlogiston) were not observed / detected. Merely ideas that could provide some explanations.

Your dishonesty was in your tacitness to my comment. Instead of explaining that you are rejecting the scientific conclusion, you made a tangential reply about some mythological argument.

What is your explanation for why you have rejected the conclusion by the way?

CoIin: I've grown tired of humoring you and tolerating your rudeness.

I do not care to have my honesty impugned, especially by a man who has behaved as you have.

This exchange cannot continue until you apologize. I will not be treated this way.

Bourbaki: Colin, TheismIsUntenable, your argument is interesting.

@Colin, I'd like to say something regarding "The scientific antirealist does not dispute the existence of everyday macroscopic OBSERVABLE entities (like the Moon).
Can we agree that photons and quarks are not entities of this kind? They are unobservable, THEORETICAL entities.".
Though the moon is on a completely different scale from subatomic particles - big enough to enable unaided detection by the human eye - It can still be argued that our indirect observations of subatomic particles are in many senses more reliable. Had we not made physical contact with the moon I doubt one's certainty of its existence would have been of varied degree. In a sense, all observation is indirect.
Human sight is in a sense much more prone to measurement error and intervening variables than the multitude of carefully conducted intricate experiments which very consistently point to the existence of subatomic particles in the framework of their respective scientific models. Now although it's true that we're using some theoretic model to infer things from empirical data, I feel that implicitly, this is always the case. The thing is, in science, this "problem" is recognized yet relegated to a status of tacit understanding, while in using our primitive senses, we're often simply unaware of it e.g when seeing stars in the sky we do not even consider that their position may in fact be very different due to something like gravitational lensing (not the best example but I have little time).

Of course this is probably not the point and I agree entirely that nothing is certain, but this applies equally to absolutely all knowledge of the environment ever gathered by humans. As I've said before, while true, I feel this is not a very productive attitude as these subtleties are perhaps not of the greatest significance to the practicing scientist. Sure, awareness is an important thing, but I think even if it's tacit and unrefined, scientists generally understand this inherent fallibility in their system.

CoIin: Your post is insightful and thought provoking as always. I'll respond with a few rather disorganized thoughts that float to mind.

First of all, I'd point out that scientific antirealism, and its close cousin instrumentalism, are not quack positions -- I am neither an enemy of science, a Barry Manilow fan, nor a religious nutcase -- but are arrived at from examination of the evidence for and against the epistemological warrant for a literal reading of scientific theories. The antirealist gladly admits all the empirical findings of science, and concedes with respect that there are good reasons for adopting a realist stance. He concludes, however, that the arguments for antirealism are even more compelling. These arguments are sketched in the opening page of this thread.

And to repeat for the umpteenth time, the antirealist does not deny that scientific theories WORK, indeed work spectacularly well; what he denies is the inference from empirical adequacy (agreement between theory and observation) to the LITERAL TRUTH of said theories.

And no, it's not just head-in-the-clouds no-life philosophers who adopt the antirealist or instrumentalist stance; I think you'll find Niels Bohr and Werner Heisenberg, for example, both displayed antirealist tendencies with regard quantum physics. From a slightly earlier period, figures such as Henri Poincare, Heinrich Hertz, Pierre Duhem, and Ernst Mach also waxed lyrically on the subject. The link below might be useful for anyone serious about getting an overview of the issues involved:-

http://plato.stanford.edu/entries/scientific-realism/

Bourbaki, you hit one of the nails on the head in your first post on Page 1, and that is the distinction between the observable and the unobservable, a critical distinction that must be defended by certain antirealists such as Bas van Fraassen, prominent advocate of "constructive empiricism" (more below).

And when the distinction breaks down, WE break down.

Er, I mean, if the distinction cannot be maintained then this form of antirealism collapses, and the entities contained in scientific theories would indeed be on an epistemic par with the macroscopic objects of our everyday experience.

Now, how this distinction is to be drawn is a matter of some disagreement among the antirealist gentry. You'd have to do your own research for more details. It's a VAGUE distinction, but that doesn't mean it can't be a meaningful one. (And "vague" here might be regarded as a technical term; much has been written recently on "vague" predicates). That the distinction between obese and thin, for example, is vague needn't imply that it's insignificant.

(In a similar vein, in their attempts to keep the riff-raff at bay, scientists have always been keen to construct demarcative walls separating bona fide science from pseudoscience or metaphysics. No one thus far has succeeded in doing so in any sharp, decisive manner though. The riffraffophobes may have to settle for vagueness.)

No matter how the antirealist defines the observable/unobservable dichotomy, it seems a matter of common sense to me at least that the farther removed we proceed from direct observation via our unaided human sensory apparatus, the more precarious the epistemic fate of the entities involved. I deliberately chose quarks for the title of the thread since quarks are about as unobservable as it gets!

The example of the Moon that you raise is a particularly interesting one, I think, for until we actually went there, as you note, our experience was limited to the visual, and thus it would seem more vulnerable than rabbits and chairs to the kind of eliminative "reduction" which befell rainbows, say. Rainbows, we're now told, have no mind-independent existence; they are merely an optical illusion; there is no "arch in the sky". Our lunar pal gratifyingly escaped with its ontological credentials largely intact, green cheese scandals notwithstanding.

Or consider the real life very macroscopic example of witches. People around 1500 might have been as dumbfounded as Theis is today by the suggestion that witches don't exist. "But LOOK. There's one right in front of you, FFS!!!"

Q : Well, had these people really observed/detected witches?
Ans: Granted that there is no such thing as a witch, then clearly NO.

Q : Had they really observed/detected WHAT THEY BELIEVED TO BE witches?
Ans : Of course.

Now, no one is suggesting witches were a scientific creation; the lesson to be learned, rather, is that the conceptual infrastructure on which our observations/detections are based are subject to constant revision. "Witch" is a theory-laden term. It's naive to suppose that any putative observation of a witch or detection of a photon is PURE; substantial theoretical baggage is carried by the observer to each encounter. The principal danger for the photon defender in particular and the scienctific realist in general, then, I'd suggest, lies not in possible flaws in experimental design or misinterpretation of current evidence, but in the spectre of these not-terribly-rare wholesale conceptual revolutions in science whereby old conceptual frameworks are jettisoned and replaced with new.

Conceptual change or meaning drift, then, represents a threat of a different kind to scientific realism than that of the disrespect shown for unobervable rights by the likes of Bas van Fraassen (see below). Think for example of all the various models of the atom that have been proposed and later discarded. Should this be regarded as entities popping in and out of epistemic existence (a la phlogiston), or can the realist make a case for continuity of reference? Are we in any sense talking about THE SAME THING?

Bourbaki, you said ... "Now although it's true that we're using some theoretic model to infer things from empirical data, I feel that implicitly, this is always the case. "

Another valuable insight. You're alluding here to the "theory ladenness" of observation that we hear a lot about these days, the ubiquity and significance of which each of us must appraise for ourselves.

In the post below this one I'm going to reproduce an excerpt from realism defender, Ernan McMullin, exploring the two topics we've just been discussing : the observable vs unobservable divide, and the threat to scientific realism posed by meaning change in science.

I leave you now with the words of scientific realist par excellence, Sgt Barnes :

"You read this scientific antirealism shit to escape from reality? I don't need this shit. I AM reality!"

CoIin: What follows is taken from "A Case For Scientific Realism" by Ernan McMullin



If one takes empiricism as a starting point, it is tempting to push it (as Hume did) to yield the demand not just that every claim about the world must ultimately rest on sense experience but that every admissible entity must be directly certifiable by sense experience.

This is the position taken by Bas van Fraassen. His antirealism is restricted to those theoretical entities that are in principle unobservable. He has no objection to allowing the reality of such theoretical entities as stars (interpreted as large glowing masses of gas) because these are, in his view, observable in principle since we could approach them by spaceship, for example. It is part of what he calls the "empirical adequacy" of a stellar theory that it should predict what we would observe should we come to a star. This criterion, which he makes the single aim of science, is sufficiently broad, therefore, to allow reality-claims for any theoretical entity that, though at present unobserved, is at least in principle directly observable by us. His antirealism has more than a tinge of old-fashioned nominalism about
it, the rejection of what he calls an "inflationary metaphysics" of redundant entities. Since neither of the two main arguments he lists for realism, inference to the best explanation and the common cause argument, are (in his view) logically compelling, this is taken to justify his application of Occam's razor.

One immediate difficulty with this position is, of course, the distinction drawn between the observable and the unobservable. Since entities on one side of the line are ontologically respectable and those on the other are not, it is altogether crucial that there be some way not only to draw the distinction but also to confer on it the significance that van Fraassen attributes to it. In one of the classic papers in defense of scientific realism, Grover Maxwell argued in 1962 that there is a continuum in the spectrum of observation from ordinary unaided seeing down to the operation of a high-power microscope. Van Fraassen concedes that the distinction is not a sharp one, that "observe" is a vague predicate, but insists that it is sufficient if the ends of the spectrum be clearly distinct, that is, that there be at least some clear cases of supposed interaction with theoretical entities which would not count as "0bserving." He takes the operation of a cloud chamber, with its ionized tracks allegedly indicating the presence of charged entities such as electrons, to be a case where "observe" clearly ought not be used . One must not say, on noting such a track: I observed an electron.

To lay as much weight as this on the contingencies of the human sense organs is obviously problematic, as van Fraassen recognizes. There are organisms with sense-organs very different from ours that can perceive phenomena such as ultraviolet light or the direction of optical polarization. Why could there not, in principle, be organisms much smaller than we, able to perceive microentities that for us are theoretical and able also to communicate with us? Is not the notion "observable in principle" hopelessly vague in the face of this sort of objection? How can it be used to draw a usable distinction between theoretical entities that do have ontological status and those that do not? Van Fraassen's response is cautious:


"It is, on the face of it, not irrational to commit oneself only to a search for theories that are empirically adequate, ones whose models fit the observable phenomena, while recognizing that what counts as an observable phenomenon is a function of what the epistemic community is (that observable is observable-to -us)."


So "observable" means here "observable in principle by us with the sense organs we presently have." But once again, why would "unobservable" in this sense be allowed the implications for epistemology and ontology that van Fraassen wants to attach to it? The question is not whether the aim of science ought to be broadened to include the search for unobservable but real entities, though something could be said in favor of such a proposal. It is sufficient for the purposes of the realist to ask whether theories that are in van Fraassen's sense empirically adequate can also be shown under certain circumstances to have likely ontological implications.

Van Fraassen allows that the moons of Jupiter can be observed through a telescope; this counts as observation proper "since astronauts will no doubt be able to see them as well from close up." But one cannot be said to "observe" by means of a high-power micro scope (he alleges) because no such direct alternative is available to us in this case. What matters here is not so much the way the instrument works, the precise physical or theoretical principles involved. It is whether there is also, in principle, a direct unmediated alternative mode of observation available to us. The entity need not be observable in practice. The iron core that geologists tell us lies at the center of the earth is certainly not observable in practice; it is a theoretical entity since its existence is known only through a successful theory, but it may nonetheless be regarded as real, van Fraassen would say, because in principle we could go down there and check it out.

The quality of the evidence for this geological entity might, however, seem no better than that available for the chromosome viewed by microscope. Van Fraassen rests his case on an analysis of the aims of science, in an abstract sense of the term "aim," on the "epistemic attitude" (as he calls it) proper to science as an activity. And he thinks that reality-claims in the case of the chromosomes, but not the iron core, lie outside the permissible aims of science. Is there any way to make this distinction more plausible?


Reference
--------------
Some theoretical entities (such as the iron core or the star) are of a kind that is relatively familiar from other contexts. We do not need a theory to tell us that iron exists or how it may be distinguished. But electrons are what quantum theory says they are, and our only warrant for knowing that they exist is the success of that theory. So there is a special class of theoretical entities whose ENTIRE warrant lies in the theory built around them. They correspond more or less to the unobservables of van Fraassen.

What makes them vulnerable is that the theory postulating them may itself change or even be dropped. This is where the problems of meaning change and of theory replacement so much discussed in recent philosophy of science become relevant. The antirealist might object to a reality-claim for electrons or genes not so much because they are unobservable but because the reference of the term "electron" may shift as theory changes. To counter this objection, it sounds as though the realist will have to provide a theory of reference that is able to secure a constancy of reference in regard to such theoretical terms. R. Rorty puts it this way:


"The need to pick out objects without the help of definitions, essences, and meanings of terms, produced (philosophers thought) a need for a "theory of reference" which would not employ the Fregean machinery which Quine had rendered dubious. This call for a theory of reference became assimilated to the demand for a "realistic" philosophy of science which would reinstate the pre-Kuhnian and pre-Feyerabendian notion that scientific inquiry made progress by finding out more and more about the same objects."


Rorty is, of course, skeptical of theories of reference generally, and derides the idea that the problems of realism could be handled by such a theory. He chides Putnam, in particular, for leading philosophers to believe that they could be. Recall the celebrated realist's nightmare conjured up by Putnam:


"What if all the theoretical entities postulated by one generation (molecules, genes, etc. as well as electrons) invariably "don't exist" from the standpoint of later science? ... One reason this is a serious worry is that eventually the following meta-induction becomes compelling: just as no term used in the science of more than 50 (or whatever) years ago referred, so it will turn out that no term used now (except maybe observation-terms if there are such) refers."


This is the "disastrous meta-induction" which at that time Putnam felt had to be blocked at all costs. But, of course, if the theoretical entities of one generation really did NOT have any existential claim on the next, realism simply would be false. It is, in part at least, because the history of science testifies to a substantial continuity in theoretical structures that we are led to the doctrine of scientific realism at all. Were the history of science NOT to do so, then we would have no logical or metaphysical grounds for believing in scientific realism in the first place. But this is to get ahead of the story. I introduced the issue of reference here not to argue its relevance one way or the other, but to note that one form of antirealism can be directed against the subset of theoretical entities which derive their definition entirely from a particular theory.

One way for a realist to evade objections of this kind is to focus on the manner in which theoretical entities can be causally connected with our measurement apparatus. An electron may be defined as the entity that is causally responsible for, among other things, certain kinds of cloud tracks. A small number of parameters, such as mass and charge, can be associated with it. Such an entity will be said to exist, that is, not to be an artifact of the apparatus, if a number of convergent sorts of causal lines lead to it. There would still have to be a theory of some sort to enable the causal tracking to be carried out. But the reason to affirm the entity's existence lies not in the success of the theory in which it plays an explanatory role, but in the operation of traceable causal lines. Ian Hacking urges that this defense of realism, which relies on experiential interactions, avoids the problems of meaning-change that beset arguments based on inference to the best explanation

CoIin: Here's a terrific resource I found : "Philosophy of Science : A Very Short Introduction" by Samir Okasha. And the whole thing is available online.

http://popovkin-av.narod.ru/materials/Okasha_Philosophy_of_Science.pdf

Of particular interest to followers of the present discussion is Okasha's overview of the scientific realism vs anti-realism debate on pages 58 - 77.

CoIin: @ Bourbaki

I offer an analogy, drawn from the legality of abortion, for your consideration and critique:-

Q1 : Should a 20 year-old Alfred Tarski be considered a human being?
Q2 : Should the zygote formed at the moment of conception which will later develop into the adult Alfred Tarski be considered a human being?

If you're like me, you'll answer "yes" to Q1 and "no" to Q2. A claim to the effect that there is no qualitative difference between the Tarski zygote and the adult Tarski seems, to me anyway, preposterous.

As we all know, though, such a distinction is not considered preposterous at all by many on the Pro-Life side of the abortion controversy. If I understand them correctly, the proto-Tarski zygote IS a human being and its abortion constitutes an act of murder.

The Pro-Choice advocate, meanwhile, having distinguished between a human and a potential human, now risks running afoul of the dreaded "Sorites paradox" : Most of us admit a meaningful distinction between a hirsute man and a bald man, yet it appears there is no definite threshold point before which he was hairy and after which he is bald.

"I wasn't bald when I went to bed last night, but upon awakening this morning I discovered to my horror that I was!"

Well, inasmuch as most of us feel decidedly uncomfortable with the idea of fully formed pre-natal infants being aborted and destroyed -- that WOULD be murder, we protest -- then for legal reasons we have to draw the line somewhere, perhaps 100 days after conception.

But surely no one supposes that a 99 day-old foetus is not human while a 100 day-old foetus IS. The line we've drawn is, in a sense, entirely arbitrary, nevertheless the arbitrariness of the demarcation does not imply that there is no meaningful distinction between a zygote and an adult human. The distinction is not artificial.

This is how I see things with the observable vs unobservable distinction vis-à-vis the scientific realism controversy.

Q3 : Should our (putative) knowledge of quarks be considered on an epistemic par with our (putative) knowledge of macroscopic objects such as tables, chairs, rabbits, and the Moon?

My unhesitating answer is no. The very suggestion is preposterous. Tables and chairs are, by anyone's standards, observable. Subsequently, we move down in scale from everyday furniture to objects visible only through a magnifying glass, to those visible only through a microscope, and so on deeper and deeper down to molecules and atoms, finally pulling into the railway terminus at Quark Central. The entities at this end of the line are surely, by anyone's standards, UNobservable and their existence -- if they exist at all -- is inferred, not observed. Our putative knowledge of the microphysical zoo at this end of the continuum is, I submit, QUALITATIVELY less secure.

Now, wherever the empiricist draws the epistemological line between the observable and the unobservable, it can't help but appear as arbitrary as the 100-day legal line drawn by the Pro-Choice advocate, and he exposes himself to the same strawman type ridicule as that of the Pro-Life activist who scoffs:-


: "So, let me get this straight. Your position is that a 100 day foetus that is human now was NOT human just a few hours -- or minutes -- ago? "

: "So, let me get this straight. Your position is that the entities we examine under a X1000 magnification microscope are observable and those examined under a X1001 magnification microscope are unobservable? "


Yes, it does appear capricious. It IS capricious and we recognize that it is. But what's the alternative? The alternative is to hold that zygotes are human beings and quarks are observable.

I think I know where I stand.

Any thoughts, B? Is the analogy appropriate?

(And where exactly on our [zygote >>> fully grown adult] continuum should we locate photons? Ten days after conception? One minute after conception? 0.000000001 seconds after conception? )


As a final remark : in matters such as the one under discussion right now, it's unfortunate that we're not normally able to test whether the disputants would be willing to put their money where their mouth is, as I suspect the results might be very revealing.

Take the devout Christian in the Religion Forum proud of his faith in God the Almighty : "Nothing could be more certain than God's existence" he might proclaim. Well, supposing he were abducted by malevolent but superintelligent aliens who informed him that the Moon and the Christian god do not both exist; only one of them does. The Christian must choose one of the two - and his child's life hangs in the balance.

If indeed nothing is more certain than God's existence, as the Christian brazenly claims, then his choice is obvious. But I do wonder ...

Likewise, if the Pro-Life activist for whom a zygote is supposedly as human as a 20 year-old adult were forced (by mischievious aliens again perhaps) to destroy one of them, which do you think she would choose?

And in our case, to the scientistic apologist who asserts with a proud (and, I daresay, not carefully thought through) faith eerily redolent of the devout Christian that our (putative) knowledge of photons' existence enjoys PRECISELY the same degree of epistemic warrant as our (putative) knowledge of the Moon's existence, I ask : "How serious are you?"

You've been abducted by these same pesky aliens. They tell you that in a hundred or a thousand years from now the human race, by and large, will have abandoned its belief in the existence of either photons or the Moon. You have to choose which one. A child's life hangs in the balance.

You've made your bed. Now, are you prepared to lie in it?

CoIin: W.V.O. Quine on realism (and his doctrine of scientific naturalism):-

"... There is nothing we can be more confident of than external things -- some of them, anyway -- other people, sticks, stones. But there remains the fact -- a fact of science itself -- that science is a conceptual bridge of our own making, linking sensory stimulation to sensory stimulation; there is no extrasensory perception.

[...]

But I also expressed, at the beginning, my unswerving belief in external things -- people, nerve endings, sticks, stones. This I reaffirm. I believe also, if less firmly, in atoms and electrons and classes. Now how is all this robust realism to be reconciled with the barren scene that I have just been depicting? The answer is naturalism : the recognition that it is within science itself, and not in some prior philosophy, that reality is to be identified and described."

(from "Things and their Place in Theories" )



Now, I'm more of an agnostic than a realist myself when it comes to the unobservable entities of scientific theories. Quine is a realist, but his is what I'd call a SENSIBLE realism. It's a realism that I can respect.

On the other hand, and with no offence intended to anyone, a scientific realism that elevates our warrant for belief in photons, quarks, and all their invisible buddies to the same level as that of sticks and stones -- including very BIG stones like, say, the Moon -- is a realism that I don't think deserves much respect at all.

The latter realism, I'd suggest, is another case of a grotesquely bloated scientism. It's perfectly alright to defend science - but surely not at ANY cost; not when the defense is no longer "within reason".