Theories and Laws and falsifiability in Science

[Beavah]

 

Sure you can "falsify" that theory. Just you can prove that God doesn't exist.

 

However, I don't believe that a theory has to be able to be proven false to be a theory. A theory is simply an organized set of ideas about a subject. Once proven, it becomes a law. Newtons Laws of Motion started out as theory.

 

Yah, I figured all da science types would want some extra space in a new thread so as to educate GW and da rest of us on what is really meant by "falsifiability" and whether Newton's "Laws" are a theory or not

 

Have at it!

 

Beavah

 

[Merlyn_LeRoy]

Theories are never proven true; they can only be shown to be false (or incomplete).

 

"Newton's laws of motion" are still a theory. There is no difference between a law and a theory in science, though law is usually used for a simple or elegant or broadly applicable or famous theory.

 

It's doubly absurd to say that Newton's laws of motion have been proven, since they are wrong. They do not accurately describe motion involving large masses or speeds near C (see Mercury's orbit). Newton's laws are still useful, though. Most NASA calculations just use Newton's laws from what I've heard.

 

A theory is falsifiable if part of the theory could be shown to be incorrect via an observation or an experiment. Mercury's orbit is observed to not be correctly predicted by Newton's laws.

[FireKat]

Merlyn_LeRoy stated "Theories are never proven true; they can only be shown to be false (or incomplete)" I beg to differ with you. You CANNOT prove a negative or that something does not exist.

And also: "There is no difference between a law and a theory in science".

Please get a refresher in science before you make those statements as they are not part of science.

[Merlyn_LeRoy]

FireKat writes:

Merlyn_LeRoy stated "Theories are never proven true; they can only be shown to be false (or incomplete)" I beg to differ with you. You CANNOT prove a negative or that something does not exist.

 

How does that even relate to what I wrote?

 

And also: "There is no difference between a law and a theory in science".

 

Please get a refresher in science before you make those statements as they are not part of science.

 

So refresh me on the difference between Newton's law of gravity and his theory of gravity.

[packsaddle]

GAD, Beavah! I had intentionally ignored that other thread and now you did THIS to us.

 

FireKat, I am interested in what you think the differences are. I know what I have in mind but you were so forceful in your rejection of Merlyn's assertion that I am wondering what your thoughts are.

 

The term 'falsifiability' is often used interchangeably with 'testability' or that sort of idea. The application of this concept has been in practice for as long as there have been experiments but Karl Popper (a philosopher) was responsible for some of the strongest statements on science and testability. I recommend his book, "The Logic of Scientific Discovery" to anyone who is sincerely interested in the concept of 'falsifiability'. Or to anyone interested in science in general for that matter.

 

There is a rich variety of ways that we 'know' things. Pragmatically, regardless of which method we choose, if it works, it works...and we tend to accept that until it doesn't work, or until a better way is discovered. In essence this accounts for the development of many current ideas in science, as well as technology, economics, political systems, etc. You get the idea. We change and adapt many of these things depending on needs and evidence.

So it is with Newton's 'laws'.

At one time we 'knew' that the earth was the center of the universe and that everything started about 7 thousand years ago, give or take a few thousand. This worked fine and was incorporated into some of the world's great religions in various ways. Later, when navigation became more important and when better observations were made of celestial objects, geocentrism became rejected by most of us...because of good evidence to the contrary. Likewise, evidence also supports a much older earth and universe. Copernicus, Galileo, and Newton and others set the stage for much of what we now recognize as modern science. With further investigation and better observations, we now understand that Newton's 'laws' still work within limits of temporal and spatial scale. For those of us interested in marksmanship, they still work fine. If we are interested in nuclear physics we must rely on another level of physics that Newton may have not imagined.

There are similar lines of advancement in biology as well.

 

But within this vast range of means of 'knowing', we have constructed descriptive terms that categorize those means in ways that are useful for communication. Such typographical conveniences are described in various dictionaries and I see that Wikipedia also has a version. I'm OK with most of them as long as we don't get preoccupied with the terms rather than the ideas. For example, while we still employ Galileo's and Newton's 'laws' of gravity, we also understand that there is, in addition, Einstein's 'gravitational theory'. I'm fairly certain that the 'theory' hasn't been put to very much practical use outside of the fields of astronomy or astrophysics.

 

The concept of 'proof' is troublesome. Strictly speaking, we can't 'prove' anything absolutely in science. For that matter we can't 'disprove' absolutely either and this leads to the conclusion that we never possess 'absolute' knowledge. I tend to think along these lines. What we DO have is a system that, in time, tends to correct erroneous ideas. Every 'fact', every 'theory', every 'law' is open to criticism and potential rejection if sufficiently good evidence to the contrary is discovered.

 

This could go on at great length so I'll stop there.

Beavah, I hope you're proud of yourself!

[epalmer84]

Let me jump in here a bit...

 

 

"In common usage, the word theory is often used to signify a conjecture, an opinion, or a speculation. In this usage, a theory is not necessarily based on facts; in other words, it is not required to be consistent with true descriptions of reality. This usage of theory leads to the common incorrect statement "It's not a fact, it's only a theory." True descriptions of reality are more reflectively understood as statements which would be true independently of what people think about them. In this usage, the word is synonymous with hypothesis."

 

"In science, a theory is a mathematical or logical explanation, or a testable model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations of the same kind, and capable of being tested through experiment or otherwise falsified through empirical observation."

http://en.wikipedia.org/wiki/Theory

 

"The laws of science are various established scientific laws, or physical laws as they are sometimes called, that are considered universal and invariable facts of the physical world. Laws of science may, however, be disproved if new facts or evidence arise to contradict them. A "law" differs from hypotheses, theories, postulates, principles, etc., in that a law is an analytic statement, usually with an empirically determined constant. A theory may contain a set of laws, or a theory may be implied from an empirically determined law."

http://en.wikipedia.org/wiki/Laws_of_science

 

"Falsifiability (or refutability or testability) is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, it means that it is capable of being criticized by observational reports."

http://en.wikipedia.org/wiki/Falsifiability

 

Newton's theory of gravitation encompasses several laws.

http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation

 

Ed

[Beavah]

Beavah, I hope you're proud of yourself!

 

Hee hee :)

 

Indeed I am.

 

But that explanation, packsaddle, had to be one of da most circuitous and overly nuanced academic dances I've read in a bit . I think yeh should give it another go, or poor Merlyn is goin' to be left all alone with his notion that a theory and a law are functionally the same thing, or that it ain't possible to falsify a (scientific) theory.

 

Einstein's 'gravitational theory'. I'm fairly certain that the 'theory' hasn't been put to very much practical use outside of the fields of astronomy or astrophysics.

 

Well, there's always GPS. That seems kinda practical.

 

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html

 

Beavah

 

[Merlyn_LeRoy]

Beavah writes:

I think yeh should give it another go, or poor Merlyn is goin' to be left all alone with his notion that a theory and a law are functionally the same thing,

 

They are. There's no hard and fast line between a theory and a law. Scientists refer to Newton's theory of gravity or his law of gravity.

 

or that it ain't possible to falsify a (scientific) theory.

 

I gave an EXAMPLE of a scientific theory being falsified; how do you get "it isn't possible to falsify a scientific theory" out of that??

 

Theories aren't ever PROVEN. They can be falsified, as Newton's theory of gravity has been. Newton's theory isn't correct, but it's close enough to be useful. It's a slightly incorrect scientific theory.

 

Even in Newton's time, stating that the acceleration of a falling body at the earth's surface due to gravity is 32 ft/sec^2 isn't accurate, because as the falling body gets closer, the acceleration increases by a tiny amount because it's now closer to the earth's center of mass, and lifting it up higher reduces it slightly. But for experiments on the earth's surface, it's normally just used as a constant acceleration, even though everyone (including Newton) knows that it isn't constant.

[packsaddle]

Third attempt. I have identified an immutable law: if you run Windows, you will frequently see the 'blue screen of death'.

I can hardly wait to get back to the Mac.

 

Thanks, epalmer, for clipping in those definitions.

Beavah, sorry about the confusion. I guess the confusion IS the reason for my attempt. I can't speak for Merlyn - only for myself. I see a spectrum of ideas that differ in degrees of confidence. Those that have withstood tests most successfully have the greatest confidence. We might categorize them as 'laws'.

Ideas which can generate testable hypotheses and which have withstood those tests so far, but whose underlying mechanisms are still being discovered, might fall into the category of 'theory' or 'body of theory'.

Ideas that are still being subjected to tests, experimental or otherwise, might be categorized as 'hypotheses'.

 

Some examples:

I think the 'Law of Uniformitarianism' has great confidence. It is one element of the foundation of science. Anything that shakes that 'law' will shake all of science.

 

'Cell Theory' is the foundation of biology. After almost 170 years of existence, it has attained great confidence although the underlying processes and mechanisms of biology are in great flux.

Cell theory originally had three elements. The last of the three was subsequently rejected as false, thus modifying the 'theory'.

 

I greatly enjoy arguing about the 'Diversity/Stability' hypothesis in ecology. We are still grasping for ways to further test this hypothesis - and in the meantime I can have fun poking an epistemological stick in the eyes of ecologists who defend the idea.

 

Would you please explain how the GPS is related to Einstein's gravitational theory? As I understand it, the GPS is a cluster of satellites that emit very precisely-timed signals that allow a receiver to detect their position and distance...and subsequently calculate the position of the detector. This I think, involves geometry and computational power (and some really precise clocks) but aside from keeping the satellites in orbit (Newtonian motions), I'm not sure what gravity has to do with it. Your web link was with respect to Einstein's theory of 'relativity', not gravitation, or are they the same thing?(This message has been edited by packsaddle)

[Beavah]

I see a spectrum of ideas that differ in degrees of confidence. Those that have withstood tests most successfully have the greatest confidence. We might categorize them as 'laws'.

 

Nah, I don't buy it, eh?

 

'Cell Theory' is the foundation of biology.

 

So "Cell Theory" is the Foundation of Biology? Then shouldn't it be a law, not a theory? Seems like it's more qualified than somethin' like Newton's Laws or the components of the Ideal Gas Law, all of which are known to be wrong!

 

epalmer's definitions from wiki were different, but every bit as silly, eh?

 

I think Merlyn's got the right of it. The term "Law" gets used for strong relationships discovered during the 17th, 18th, and early 19th century when that language was in vogue ("natural laws"). It's an historical accident of terminology arisin' from da epistemology of the time. Da effort to try to make a distinction between "law" and "theory" these days arises from misguided elementary and middle school teachers.

 

Now there I go agreein' with Merlyn. End of the world must be the day after tomorrow.

 

Would you please explain how the GPS is related to Einstein's gravitational theory?

 

I'm da wrong guy to be askin' that, I think. I'm just a hobbyist astronomer who likes helpin' with astronomy MB at camp.

 

My understandin' is that there are two effects that need to be compensated for in GPS. One is that the satellites are movin', and movin' clocks run slower when viewed from a stationary clock. That's special relativity. Second is that clocks that are deeper in a gravity well will run slower when viewed by a clock farther away from a gravitational source. Dat's why black holes redshift light, eh? So an earth-based clock will run slower than a satellite-based clock. That's general relativity/gravitation.

 

The two effects partially cancel, but for the altitude and speed GPS satellites work at, the gravitational effect is stronger. Satellite clocks run faster than ground-based clocks, because the ground-based clock is stuck closer to the earth's gravitation. Now you'd think the effect would be small, and it is... but even a small effect counts when you're talkin' about da level of precision involved in GPS. It's about 5 orders of magnitude greater than da slew error of the atomic clocks, and at least several orders of magnitude greater than some of the other error components. Makes a big difference.

 

B

 

[packsaddle]

I guess my point is that even the 'laws' are open to examination, test, and modification if sufficient evidence is discovered. Perhaps there is something to the historical artifact explanation and today's 'theories' just never made it to 'law' status. If you make a list of all the so-called 'laws' of those past centuries you might find quite a few that have been rejected. For me, it isn't all that important, this distinction. Likewise for 'cell theory', whether it is called 'theory' or 'law' is less important than the ideas and understanding that we have and are discovering. What IS important is that all of it, regardless of what we call it, remains subject to review and critical examination...perhaps modification or rejection. That's the 'falsifiability' part of the original question.

 

I'm hoping the 'proof' part is clear enough already. If we perform a test of some kind and discover evidence that conflicts with the idea, then we can say that there is a problem to be resolved some way, or else the idea must be set aside or rejected.

I like to pick on the 'cold fusion' guys, Pons and Fleischman, for this. They thought they had a great, revolutionary idea. Tests failed to support their claims. Was it disproven? They are still working on it. I would say it is unsupported by independent tests.

However, if the tests had confirmed the effect. And if it led to a revolutionary new source of nearly unlimited energy, I'd have to put my money on the proof side. I hope they're right but my money is still in the bank.

 

Regarding GPS: OK, I buy the argument. Don't understand it - but I know how to use the technology and that's good enough for me. I'll add that to the practical list. That's one example, you know of any more?

[packsaddle]

Beavah, From the NAS report I noted in another thread (Evolution, Science, and Creationism: National Academy of Sciences Report - 2007), some of your questions are addressed. FYI, this report can be downloaded for free. Long clip...

 

Some essential quotes from the report.

 

Page 10: In science, explanations must be based on naturally occurring phenomena. Natural causes are, in principle, reproducible and therefore can be checked independently by others. If explanations are based on purported forces that are outside of nature, scientists have no way of either confirming or disproving those explanations. Any scientific explanation has to be testable there must be possible observational consequences that could support the idea but also ones that could refute it. Unless a proposed explanation is framed in a way that some observational evidence could potentially count against it, that explanation cannot be subjected to scientific testing.

Because observations and explanations build on each other, science is a cumulative activity. Repeatable observations and experiments generate explanations that describe nature more accurately and comprehensively, and these explanations in turn suggest new observations and experiments that can be used to test and extend the explanation. In this way, the sophistication and scope of scientific explanations improve over time, as subsequent generations of scientists, often using technological innovations, work to correct, refine, and extend the work done by their predecessors.

 

Page 10 insert: Definition of Science

The use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process.

 

Page 11:

Is Evolution a Theory or a Fact?

 

It is both. But that answer requires looking more deeply at the meanings of the words theory and fact.

 

In everyday usage, theory often refers to a hunch or a speculation. When people say, I have a theory about why that happened, they are often drawing a conclusion based on fragmentary or inconclusive evidence.

The formal scientific definition of theory is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the Sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales (the theory of plate tectonics). Like these other foundational scientific theories, the theory of evolution is supported by so many observations and confirming experiments that scientists are confident that the basic components of the theory will not be overturned by new evidence. However, like all scientific theories, the theory of evolution is subject to continuing refinement as new areas of science emerge or as new technologies enable observations and experiments that were not possible previously.

 

One of the most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not yet been observed. For example, the theory of gravitation predicted the behavior of objects on the Moon and other planets long before the activities of spacecraft and astronauts confirmed them. The evolutionary biologists who discovered Tiktaalik (see page 2) predicted that they would find fossils intermediate between fish and limbed terrestrial animals in sediments that were about 375 million years old. Their discovery confirmed the prediction made on the basis of evolutionary theory. In turn, confirmation of a prediction increases confidence in that theory.

 

In science, a fact typically refers to an observation, measurement, or other form of evidence that can be expected to occur the same way under similar circumstances. However, scientists also use the term fact to refer to a scientific explanation that has been tested and confirmed so many times that there is no longer a compelling reason to keep testing it or looking for additional examples. In that respect, the past and continuing occurrence of evolution is a scientific fact. Because the evidence supporting it is so strong, scientists no longer question whether biological evolution has occurred and is continuing to occur. Instead, they investigate the mechanisms of evolution, how rapidly evolution can take place, and related questions.

 

Page 11 and 12:

In science it is not possible to prove with absolute certainty that a given explanation is complete and final. Some of the explanations advanced by scientists turn out to be incorrect when they are tested by further observations or experiments. New instruments may make observations possible that reveal the inadequacy of an existing explanation. New ideas can lead to explanations that reveal the incompleteness or deficiencies of previous explanations. Many scientific ideas that once were accepted are now known to be inaccurate or to apply only within a limited domain.

 

However, many scientific explanations have been so thoroughly tested that they are very unlikely to change in substantial ways as new observations are made or new experiments are analyzed. These explanations are accepted by scientists as being true and factual descriptions of the natural world. The atomic structure of matter, the genetic basis of heredity, the circulation of blood, gravitation and planetary motion, and the process of biological evolution by natural selection are just a few examples of a very large number of scientific explanations that have been overwhelmingly substantiated.

 

Science is not the only way of knowing and understanding. But science is a way of knowing that differs from other ways in its dependence on empirical evidence and testable explanations.

[Beavah]

In science, a fact typically refers to an observation, measurement, or other form of evidence that can be expected to occur the same way under similar circumstances. However, scientists also use the term fact to refer to a scientific explanation that has been tested and confirmed so many times that there is no longer a compelling reason to keep testing it or looking for additional examples. In that respect, the past and continuing occurrence of evolution is a scientific fact. Because the evidence supporting it is so strong, scientists no longer question whether biological evolution has occurred and is continuing to occur. Instead, they investigate the mechanisms of evolution, how rapidly evolution can take place, and related questions.

 

Yah, they seem to be gettin' a little bit ahead of themselves here, eh?

 

I wouldn't be callin' theories with a large amount of evidence "facts", eh?

 

Da description they give would easily have applied to Newtonian Gravitation, eh? It was tested and confirmed so many times that there was no longer a particular need to keep testin' it. Then Einstein comes along and says it's completely wrong theoretically, and only a decent approximation practically.

 

The same might have been said about electromagnetism, or lookin' further back, geocentrism.

 

The only "fact" in science is that sometimes new facts cause us to completely rethink our way of lookin' at things.

 

Evolution by natural selection has been around a bit, but yeh just never know.

 

B

 

[packsaddle]

I just thought that the NAS would tend to have more credibility than Wikipedia or I have. But "..yeh just never know." Yes, my point exactly.