Logical Positivism

[Michael Stuart Kelly]

Bob,

I was going to agree with you until you came up with that ruler thing.

By your standard, how do you know you know anything? Not about rulers or anything like that. How do you know your mind functions properly? What is your standard of verification? Another mind? Is that "theory laden"?

I do agree that certain presumptions have to be made in order for awareness stuff to work. One is that things exist. Another is that they have identity. Another is that you have consciousness and can know stuff.

I even have another. Our minds are made out of the same stuff as the rest of the universe. We are not freaks of existence. So if our minds are made out of the same stuff as everything else, they work in the same manner as everything else.

That means both determinism and volition exist in the universe.

In your ruler example, you want to subject the law of identity itself to scientific verification. But you can't without using the law of identity to validate your own mind (i.e., deciding that it is an individual awareness that is competent to judge scientific facts). In other words, you can only presume that the identity of rulers does not exist if you accept the identity of your own mind. Otherwise you can't presume anything at all.

btw - I never did like the term "theory laden." To me, after you cut out all the gobbledygook, that always sounds like simple conceptual thought. In other words, when I translate the basic argument by using this term, it comes out that you have to think in order to think about existence, thus your thoughts are not valid nor are they scientific because they are theory laden based on thinking.

How something can be scientific without anyone thinking is beyond me...

Michael

[BaalChatzaf]

Bob,

I was going to agree with you until you came up with that ruler thing.

By your standard, how do you know you know anything? Not about rulers or anything like that. How do you know your mind functions properly? What is your standard of verification? Another mind? Is that "theory laden"?

Eyes and ears and hands. A ruler seems rigid, so we suppose that it is rigid. However our physical theory which depends on the assumed rigidity of our measuring rods is also used to justify the assumption. Theory laden-ness builds in a kind of circularity. It cannot be avoided. We make those assumptions and conventions that match our perceptions in a comfortably close manner. Sometime this backfires. For example, Einstein showed that length depends on relative motion in an inertial frame. It is not an inherent and absolute value. Ditto for time. A second is not necessarily a second. It depends on what frame of reference one is using. And besides Poincare pointed out that we cannot lay intervals of time side by side to compare them. We have to equate an interval of time with a cycle of motion of a harmonic oscillator. But that is a convention.

Theory laden-ness is pesky, but we have to live with it. That is why we have to assume uniformity of laws in order to have a science at all. So uniformity of law produces theory which is then used to justify uniformity of law. Around and around it goes. But the game is the same. Save the appearences. Make the phenomenon match the theory, by hook or by crook.

Ba'al Chatzaf

[Xray]

[Robert Campbell]:

"I'm still not sure what a New Atheist is. If the appellation covers Christopher Hitchens, Richard Dawkins, and Daniel Dennett—in which case I have to wonder about the "New" part—none of these gentlemen is a Logical Positivist."

(end quote)

Imo the label New Atheists is used to categorize the leading figures (plus their supporters) of the recent atheist movement which has, starting in Europe a few years ago with the publication of Dawkins' book, swept over the western world.

Suddenly atheists seem to attract a far larger public, they are sought by the media, sit in talk shows offering their philosophies as viable to an ever growing number of people open to the idea of there being no god.

I still grew up at a time where "the atheist" was viewed by the church as someone who dared to "challenge god", a figure like the devil's disciple so to speak.

To deny the existence of god as such was considered as a blasphemy of ultimate magnitude; the new atheist movement just shows to what extent religious institutions like e. g. the catholic church have lost their grip on people's minds.

Dawkins & Co may be polemic, often too simplistic - but at least they try to get believers in transcendence to rethink their premises. It is often the encounter with such books which can work as a catalyst.

Edited July 11, 2009 by Xray

[Selene]

...subjectively speaking

YAWN

[Michael Stuart Kelly]

Bob,

Although I agree with the gist of what you say, there is a sour note in the symphony. I get the impression that you are arguing from a position where science exists without thought, that the human being is somehow separate from reality and part of it at the same time, in the same respect, to the same degree, etc.

Michael

[kiaer.ts]

Boy, for someone who prides himself on his hard-hearted scientific attitude, your faith in some as yet undiscovered miracle and your capacity for selective adherance to scientific evidence is impressive. What do you mean, we haven't looked everywhere? Do you mean that orbiting around some distant star whose light that we see shows that it obeys all the same laws of physics that we do there may be a planet on which there may be a rock under which, when we look, we may find a happy Bob Kolker, violating all the laws of the known universe? Your remark argument is arbitrary. We have looked everywhere that matters for any reasonable meaning of your claim. The laws of the universe are uniform everywhere we have looked, and we have looked at a sphere 13.5 billion years in diameter. If you are troubled by leprechauns in your dreams that is your problem.

I don't believe in miracles. I believe in FACTS. When we have every last FACT perhaps we can verify that our universally quantified laws of physics are in FACT true. Please write when we have every last FACT there is recorded properly along with proof that theyu are recorded properly. In the mean time I will assume whatever I have to assume to permit universally quantified physical laws to be instantiated generally. If that means making a conventional assumption of uniformity, then that is what I do.

Also write us when we have a method of empirical verification that is NOT theory laden. For example you verify that your bookshelf is three feet two inches long (plus or minus an eight of an inch). How do you do that. You use a ruler. But you assume your ruler is rigid and carrying it from your storage closet to your bookshelf has not altered its length. But how do you know it is rigid and transporting it has not altered its length? Do you use another ruler to check? If so, how do you know that second ruler is rigid enough to check the first? Ah! You assert a theory that implies rulers made of materials such as hardwood or steel are rigid. But how do you know those theories are true in the application to your rulers? You need yet another set of verifications based on assumptions and so on and so on. In short you can't get away from theory laden modes of verification. So how do you sleep at night. By assuming the assumptions underlying your most basic theories (from which you infer the soundness of all your other theories) are true. In short you do what ever you have to do to draw conclusions from your empirical tests.

And so it goes.

Read Henri Poincare's -Science and Hypothesis- to find out why we cannot get away from conventions in science. Science is not totally reducible to apodictic judgments. At some point we have to resort to some kind of induction or abduction to have universal laws in hand. Or put it another way: there is no way to deduce the universe from necessarily true judgments. We have resort to observational contingencies. No choice. We either do that or we have no science. Among the observational contingencies we are forced to infer uniformity of law by some kind of induction. Our most imposing castles of thought are built on somewhat squooshy foundations. That is what we get for not being Gods or not being Omniscient and Omnipotent.

Do not be overly shocked to fiind out someday that your favorite theory in which you have the greatest confidence has been empirically falsified. That possibility always exists. In the mean time use the theories which are supported by massive amounts of empirical verification and are not yet falsified. (Think of Newtonian Gravitation before it was found out that it did not predict the orbit of Mercury correctly). And don't be totally confident in The Theory of General Relativity. Said theory did not predict Vera Ruben's motion curves which contradict Keplerian motion without some help, and Fritz Zwicky's Dark Matter. Dark Matter is a conventional hypothesis that has been formulated to save the Theory of General Relativity. It is the only way to keep Keplerian Motion of stars in galaxies intact (at this juncture).

To answser you other question the Theory of General Relativity has never been tested inside a Black Hole. There is no reason to believe it will hold inside a Black Hole. No one has been inside a Black Hole --- ever. Not only that even if someone did go in he would not be able to tell someone outside what he found. And without Black Holes (a hypothetical entity) we cannot account for the strange dances that some stars do around no visible body.

As long as we depend on obsevations and instruments we will have to play the Very Old Game of Saving the Appearances. Scientists have been doing it for nearly three thousand yers.

Ba'al Chatzaf

You are cute, like a child who thinks he is invisible when he closes his eyes, Bob. The issue is the plain old common sense uniformity of nature, as in do the same broad rules apply everywhere, or, is the nature of the universe such that far away objects are rule goverened in their interaction with us. The simple common sense answer is yes, look at the light of the furthest visible stars, it shows that the laws of physics are the same there and throughout all the space and time between them and us through which their light has passed. You know this is the case yourself, Bob, and you don't doubt it. As for my theories being empirically invalidavted, which ones? And why not yours? Whys is your skepticism indubitable? My theory that the fact that light from distant stars gets here implies that the nature of the forces is the same here, there, and in between? What will empirically invalidate that? The discovery that the distant stars we are seeing aren't distant stars? That is the empirical given, that we see different stars. You want to keep open minded that the stars may not be stars, that their spectra may not be spectra? You don't mean or believe what you are saying. And more important, neither does anybody reading this who really wants an answer to the question, rather than a self-contradictory nonsense position held to prove the Humean subtlety of his thought. Hume loved to make noises as if our knowledge of causation was myth and that the laws of reality might dissolve before our eyes. But he was very careful to maintain his rights as an author and to collect his royalties. As of this point, I appoint Adam to continue any further arguments on behalf of my postion.

[Dragonfly]

It is not the business of philosophy, science, or any reasonable person to consider something for which no evidence appears to exist. Your reasoning here is epistemological poison.

Bob is right. Uniformity of nature has not been not proved and cannot be proved, it is a hypothesis that seems to work well for that part of the universe we can observe. However, we do not know whether that uniformity can be extrapolated to a larger universe or a multiverse of which our visible universe is only a small part. Nothing can be more treacherous than so called "common sense". Many notions that were common sense during centuries were destroyed by the emergence of new and successful theories, like the theory of relativity and quantum mechanics. It turned out that you cannot extrapolate the behavior of systems moving at low speeds to speeds comparable to the speed of light, and that you cannot extrapolate the deterministic and localized behavior of macroscopic systems to systems at atomic scales.

[Michael Stuart Kelly]

Dragonfly,

Your post conveys the exact meaning of "open-ended concepts."

Michael

[kiaer.ts]

It is not the business of philosophy, science, or any reasonable person to consider something for which no evidence appears to exist. Your reasoning here is epistemological poison.

Bob is right. Uniformity of nature has not been not proved and cannot be proved, it is a hypothesis that seems to work well for that part of the universe we can observe. However, we do not know whether that uniformity can be extrapolated to a larger universe or a multiverse of which our visible universe is only a small part. Nothing can be more treacherous than so called "common sense". Many notions that were common sense during centuries were destroyed by the emergence of new and successful theories, like the theory of relativity and quantum mechanics. It turned out that you cannot extrapolate the behavior of systems moving at low speeds to speeds comparable to the speed of light, and that you cannot extrapolate the deterministic and localized behavior of macroscopic systems to systems at atomic scales.

Your universe that can't be observed or your multiverse is an ad hoc creation that serves no point other than to keep alive a pointless pet theory of yours. We'll worry about your observations of what can't be observed when you have observed it. Until then, your claim is arbitrary, vacant and, as it turns out regarding the universe that matters, false.

[Michelle]

It is not the business of philosophy, science, or any reasonable person to consider something for which no evidence appears to exist. Your reasoning here is epistemological poison.

Bob is right. Uniformity of nature has not been not proved and cannot be proved, it is a hypothesis that seems to work well for that part of the universe we can observe. However, we do not know whether that uniformity can be extrapolated to a larger universe or a multiverse of which our visible universe is only a small part. Nothing can be more treacherous than so called "common sense". Many notions that were common sense during centuries were destroyed by the emergence of new and successful theories, like the theory of relativity and quantum mechanics. It turned out that you cannot extrapolate the behavior of systems moving at low speeds to speeds comparable to the speed of light, and that you cannot extrapolate the deterministic and localized behavior of macroscopic systems to systems at atomic scales.

You said it. Uniformity holds for the observable universe. Man can only obtain knowledge about the observable universe. Your speculations exist outside of the context of man's knowledge.

Do invisible pin unicorns exist? You cannot say "no," because it is quite possible that, somewhere out in the depths of space, or perhaps in another dimension, where nature is suitably distinct enough from our own to allow a creature to be both invisible and pink at the same time in the same respect, invisible pink unicorns do, in fact, exist. But we have no reason to think that they exist, the traits they possess are self-contradictory, and there is no justified reason to entertain their existence. Thus, it would be absurd to speak of invisible pink unicorns as being anything other than pure fantasy. This is not saying that they cannot exist. They might, in a universe or section of a universe that is different from our own. But, within the context of man's knowledge of the universe, they don't exist. So we are justified in saying "invisible pink unicorns do not exist," as we are justified in saying "the universe is uniform in the laws governing its nature."

Of course, if evidence to the contrary surfaces, then a person is justified in taking an interest in it, as they have a good reason to. Until then, however, you should just admit that there is no celestial teapot.

Edited July 11, 2009 by Michelle R

[Dragonfly]

Your universe that can't be observed or your multiverse is an ad hoc creation that serves no point other than to keep alive a pointless pet theory of yours. We'll worry about your observations of what can't be observed when you have observed it. Until then, your claim is arbitrary, vacant and, as it turns out regarding the universe that matters, false.

No, I don't make a claim, you do. I do not claim that nature is not uniform, I only say that you cannot prove your claim of the uniformity of nature. We can only say that we haven't seen contradictory evidence so far, but as Bob said, absence of evidence is not evidence of absence.

[Dragonfly]

You said it. Uniformity holds for the observable universe. Man can only obtain knowledge about the observable universe. Your speculations exist outside of the context of man's knowledge.

With every second we get new information about the observable universe. Scientific knowledge is tentative, that we've seen only white swans so far doesn't imply that all swans are white.

Do invisible pin unicorns exist?

Wrong analogy, as the existence of invisible pink unicorns is a positive claim. I don't make any positive claim, I only say that you cannot prove your positive claim.

[Michael Stuart Kelly]

Here is a quote that is pertinent to this discussion. ITOE, "7. The Cognitive Role of Concepts," pp. 65-66.

Remember that the perceptual level of awareness is the base of man's conceptual development. Man forms concepts, as a system of classification, whenever the scope of perceptual data becomes too great for his mind to handle. Concepts stand for specific kinds of existents, including all the characteristics of these existents, observed and not-yet-observed, known and unknown.

It is crucially important to grasp the fact that a concept is an "open-end" classification which includes the yet-to-be-discovered characteristics of a given group of existents. All of man's knowledge rests on that fact.

In other words, the categories and known details are absolute, but yet-to-be-discovered details (and categories, for that matter) are... well... yet-to-be-discovered.

Here is how this works on a practical level with an easy example. People used to think the earth was flat. Later it was discovered by other people that the earth is a globe. The earth (the concept, i.e., the planet) still is the earth. The flatness (the detail) is still basically flat on immediate perception, but the scope has broadened. Other details are added to the perceived flatness. That flatness did not go away. It better not, either, if we want to build skyscrapers. It merely no longer applies to the whole shebang.

(This scope issue, incidentally, is my main criticism of several of Rand's ideas.)

Michael

[Michael Stuart Kelly]

One other thing.

What do you guys mean by "uniformity of nature"?

Fundamental axioms or something more?

Michael

[BaalChatzaf]

One other thing.

What do you guys mean by "uniformity of nature"?

Fundamental axioms or something more?

Michael

Uniformity of nature = assumptions that the fundamental physical laws hold everywhere in the cosmos. A special case is that the laws of physics hold in all inertial frames of reference.

Ba'al Chatzaf

[Selene]

Ba'al:

If we added known before cosmos, you would be in agreement?

Uniformity of nature = assumptions that the fundamental physical laws hold everywhere in the cosmos

And:

"This scope issue, incidentally, is my main criticism of several of Rand's ideas..." <<< In what way Michael

Adam

[Xray]

(bolding mine)

Here is a quote that is pertinent to this discussion. ITOE, "7. The Cognitive Role of Concepts," pp. 65-66.

Remember that the perceptual level of awareness is the base of man's conceptual development. Man forms concepts, as a system of classification, whenever the scope of perceptual data becomes too great for his mind to handle. Concepts stand for specific kinds of existents, including all the characteristics of these existents, observed and not-yet-observed, known and unknown.

It is crucially important to grasp the fact that a concept is an "open-end" classification which includes the yet-to-be-discovered characteristics of a given group of existents. All of man's knowledge rests on that fact.

In other words, the categories and known details are absolute, but yet-to-be-discovered details (and categories, for that matter) are... well... yet-to-be-discovered.

Here is how this works on a practical level with an easy example. People used to think the earth was flat. Later it was discovered by other people that the earth is a globe. The earth (the concept, i.e., the planet) still is the earth. The flatness (the detail) is still basically flat on immediate perception, but the scope has broadened. Other details are added to the perceived flatness. That flatness did not go away. It better not, either, if we want to build skyscrapers. It merely no longer applies to the whole shebang.

(This scope issue, incidentally, is my main criticism of several of Rand's ideas.)

Michael

How can categories (which are arbitrary groupings by similarities) be "absolute"?

Edited July 11, 2009 by Xray

[Michael Stuart Kelly]

Uniformity of nature = assumptions that the fundamental physical laws hold everywhere in the cosmos. A special case is that the laws of physics hold in all inertial frames of reference.

Bob,

Those "fundamental physical laws" should be specified because "fundamental physical laws" have not even held throughout human history.

Existence holds. Identity holds. Consciousness holds. Even physical laws within "frames of reference"—your "special case"—hold.

(In Objectivism, this is called "contextual absolute" and those who itch to bash Objectivism at all costs have great fun mocking this phrase. I admit the phrase is clunky, but those who mock it misrepresent its meaning.)

Unless people specify this, they will keep talking past each other when they disagree over "uniformity of nature."

Michael

[Michael Stuart Kelly]

How can categories (which are arbitrary groupings by similarities) be "absolute"?

Xray,

You need to understand "objective" before this will make sense to you.

Michael

[anonrobt]

I'd love to see a Logical Positivist account for the uniformity of nature. I've been harping the New Atheists about this for a long time.

The uniformity of nature cannot be proved or accounted for. It is assumed. Without the assumption of uniformity there can be no science based on universally quantified postulates.

There is no way empirically establish the uniformity nature because no one can visit every place in the cosmos and test the laws of physics empirically. So it must be assumed.

Ba'al Chatzaf

So much for the law of identity, huh...

[Xray]

How can categories (which are arbitrary groupings by similarities) be "absolute"?

Xray,

You need to understand "objective" before this will make sense to you.

Michael

Just give me the definition of "objective" if you claim I don't "understand" the term. TIA.

Meanwhile, maybe others here can answer the question I asked you:

How can categories (which are arbitrary groupings by similarities) be "absolute"?

Edited July 12, 2009 by Xray

[BaalChatzaf]

So much for the law of identity, huh...

The Law of Identity (or as I prefer, the Law of Non-Contradiction) does NOT imply that physical laws must be uniform at all times and places in the spacetime continuum. There is no logical contradiction in non-uniformity.

Ba'al Chatzaf

[Guyau]

From my essay Induction on Identity

Objectivity V1N3 (1991, 37–39)

VIII. Hume – Uniformity

Hume thought that if we did have a valid rational basis for induction, it would be the principle “that instances, of which we have had no experience, must resemble those, of which we have had experience, and that the course of nature continues always uniformly the same” (T 89). Taken superficially, this principle, the ‘uniformity of nature’ principle is false and uninteresting (Mill 1973, 3.2.2). Wells do not always work, let alone work “uniformly,” and the atomic chemical elements did not always exist. I think the principle that Hume was really trying to get at was an identity principle, something like the principle of substantive propagation, something like, “whether things continue the same or change, there will be reasons, growing out of the way things were at earlier times, for the way things are at later times.”

Hume says it is possible the uniformity principle is false since we can conceive of it being false. The principle is false under the superficial reading, quite apart from Hume’s rationalism. Under the identity reading, the principle stands up to all of our experience, provided we construe “growing out of” in the broad causal mode. The principle stands up to much of our experience even where “growing out of” is construed in the narrow mode.

[[From Section VI, p. 25]]

[[Hume’s commonsense principle that same causes yield same effects was endorsed also by Aristotle: “It is a law of nature that the same cause, provided it remain in the same condition, always produces the same effect” (GC 336a27–28). Ockham endorsed the principle in a form close to Hume’s: “Causes of the same kinds are effective of effects of the same kinds” (Weinberg 1965, 142). Ockham took this principle to be necessary and self-evident. As the principle is formulated by Ockham or Hume, it is subject to two interpretations. One, a broad one, I shall endorse in a moment. The other—and this is what both Ockham and Hume (E 64) most likely meant—is just the principle as stated without ambiguity by Aristotle. I think we should be wary of Aristotle’s principle. Hereafter, I shall refer to it as the narrow mode of causality. Although it obtains through vast ranges of experience, throughout much of existence, it evidently does not obtain for physical processes in quantum regimes [a, b] . . . . I suggest we reformulate the principle more broadly thus: “Identical existents, in given circumstances, will always produce results not wholly identical to results produced by different existents in those same circumstances.” Application of the law of identity to action or to becoming would seem to require only this much (contrary to Peikoff 1991, 14–15).]]

“Very well,” a modern Humean might say, “how do we know that this identity principle, the substantive propagation principle, with the broad mode of cause, will be true in the future?” Well, how do we know there will be a future? Because we know that our being here just now does not make now cosmically special. . . . At this stage of modern science [1991], we reasonably ask whether the universe will eventually contract to a singularity, whether such singularity would be final, whether time would stop. But the end of time, if there be such, is very far off and is not predicated on any fantasies one might indulge concerning the world ending tomorrow.

. . . .

The modern Humean would continue shamelessly: “Yes, Einstein’s field equations, Hamilton’s principle, and the conservation of energy may have all held up until now, but what about tomorrow? We concede that since the beginning of time there has been nothing cosmically special about present times per se, but what about present times per se in the future? And again, what about this principle of substantive propagation, this principle that the ways things will be grow out of the ways things have been? That may have been true yesterday, but what about tomorrow?”

I shall give a negative argument, then a positive argument. . . .

The negative argument is this: The principle that the way things will be grow out of the ways things have been is not a bald analytic statement. It is not a stupid tautology. One could go ahead and say “perhaps it is not always the case that the way things will be grow out of the ways things have been” without having misunderstood the simple meanings of the terms of the principle. Suppose the principle were false. Would the principle of noncontradiction then be true tomorrow? If the principle of noncontradiction is true tomorrow without having been an identity in time with itself today, then it is a radical, Humean contingent truth. Then, in the Humean mentality, it could be false day after tomorrow. Then was it true today? Suppose the principle of noncontradiction is true for any tomorrow but only contingently so. Better yet, suppose we just return to reality. There we find all the necessity worth having. There we find the principle of noncontradiction and our principle of substantive propagation always true.

. . . .

The positive argument [begins with] this: The principle that the ways things will be grow out of the ways things have been comprehends all of its specific occasions. An oak grows from an acorn, a pair of gamma photons are born from the annihilation of an electron with a positron, mammals evolved from reptiles, the view became clear because I washed the window—these are specific occasions of the principle. Why not just stick to the specific occasions of the principle? Why try to summarize them all in a single principle? What work does our substantive propagation principle do? It helps us think and learn.

. . . .

David Hume is very pleased to have received these insights into how it is useful to suppose always that the ways things will be grow out of the ways things have been. He really would like to see our positive justification for thinking this principle always true.

Our principle provides a unifying explanation of our successes in finding more specific unifying explanations. Our principle has the connective character of justified true belief; it is a belief which tracks truth (Nozick 1981, 169–78). Had the principle been false in our experience, we could have noticed it . . . . Were the principle to be false in some corner in the future, we could notice that . . . . The principle grew out of experience; it is a self-subsuming principle; it is an instance of itself. New experience has grown from the principle (Mill 1973, 3.3.1). Our principle has bearings of a fundamental justified justification (Nozick 1981, 137–40, 641–42).

References

Aristotle 1984 [c. 348–322 B.C.]. The Complete Works of Aristotle. J. Barnes, editor. Princeton.

Hume, D. 1975 [1893, 1748]. Enquiries Concerning Human Understanding. 3rd ed., L.A. Selby-Bigge, editor. Oxford.

——. 1978 [1888, 1740]. A Treatise of Human Nature. 2nd ed., L.A. Selby-Bigge, editor. Oxford.

Mill, J.S. 1973 [1848]. A System of Logic Ratiocinative and Inductive. University of Toronto.

Nozick, R. 1981. Philosophical Explanations. Harvard.

Weinberg, J.R. 1965. Abstraction, Relation, and Induction. University of Wisconsin.

[Xray]

[Flagg]:

I'd love to see a Logical Positivist account for the uniformity of nature. I've been harping the New Atheists about this for a long time.

Flagg,

Do you think "uniformity of nature" necessarily points to a god as "creator"?

Edited July 13, 2009 by Xray

[Robert Campbell]

I don't believe in miracles. I believe in FACTS. When we have every last FACT perhaps we can verify that our universally quantified laws of physics are in FACT true. Please write when we have every last FACT there is recorded properly along with proof that theyu are recorded properly. In the mean time I will assume whatever I have to assume to permit universally quantified physical laws to be instantiated generally. If that means making a conventional assumption of uniformity, then that is what I do.

Also write us when we have a method of empirical verification that is NOT theory laden. For example you verify that your bookshelf is three feet two inches long (plus or minus an eight of an inch). How do you do that. You use a ruler. But you assume your ruler is rigid and carrying it from your storage closet to your bookshelf has not altered its length. But how do you know it is rigid and transporting it has not altered its length? Do you use another ruler to check? If so, how do you know that second ruler is rigid enough to check the first? Ah! You assert a theory that implies rulers made of materials such as hardwood or steel are rigid. But how do you know those theories are true in the application to your rulers? You need yet another set of verifications based on assumptions and so on and so on. In short you can't get away from theory laden modes of verification. So how do you sleep at night. By assuming the assumptions underlying your most basic theories (from which you infer the soundness of all your other theories) are true. In short you do what ever you have to do to draw conclusions from your empirical tests.

And so it goes.

Read Henri Poincare's -Science and Hypothesis- to find out why we cannot get away from conventions in science. Science is not totally reducible to apodictic judgments. At some point we have to resort to some kind of induction or abduction to have universal laws in hand. Or put it another way: there is no way to deduce the universe from necessarily true judgments. We have resort to observational contingencies. No choice. We either do that or we have no science. Among the observational contingencies we are forced to infer uniformity of law by some kind of induction. Our most imposing castles of thought are built on somewhat squooshy foundations. That is what we get for not being Gods or not being Omniscient and Omnipotent.

Do not be overly shocked to fiind out someday that your favorite theory in which you have the greatest confidence has been empirically falsified. That possibility always exists. In the mean time use the theories which are supported by massive amounts of empirical verification and are not yet falsified. (Think of Newtonian Gravitation before it was found out that it did not predict the orbit of Mercury correctly). And don't be totally confident in The Theory of General Relativity. Said theory did not predict Vera Ruben's motion curves which contradict Keplerian motion without some help, and Fritz Zwicky's Dark Matter. Dark Matter is a conventional hypothesis that has been formulated to save the Theory of General Relativity. It is the only way to keep Keplerian Motion of stars in galaxies intact (at this juncture).

Bob K,

As far as I understand it, the uniformity of nature is something that scientists assume. It is not a basic axiom, subject to reaffirmation through denial.

OK so far... but what's the import of calling the assumption a convention? We can have a convention about the uniformity of nature if, among other things, I assume that you assume that those other guys assume, and so on, that physical laws apply everywhere. But the conventionality doesn't seem to be at the core of it.

I don't have a problem with the claim of theory-ladenness either, if all you mean by it is that assumptions have to be true (sometimes entire theories have to be true) in order for our measurement procedures to function as they are supposed to.

When the claim is made that a measurement or observation is laden with the very theory being tested, then I see things getting dicier.

What I'm trying to do here, in part, is peel away positivistic vocabulary from positions that don't appear to be consistent with Logical Positivism (which, we may faintly recall, was the original topic of this thread). Is your notion of a convention the same notion that the Logical Positivists were fond of appealing to? And isn't theory-ladenness of observation normally taken as a mark of post-positivistic philosophy of science?

Robert C