What "theory" means in science

[rogue06]

Apparently the lack of understanding by many of what a theory is in science leads some to talk about how things like evolution are "only a theory" and therefore dismiss it on those grounds. But as the National Academy of Science explains, "theories are the goal of science" (see below) not, as the author and biochemist Isaac Asimov so eloquently put it, "something you dreamt up after being drunk all night."

Noted biologist Douglas J. Futuyma explains in his book "Evolution":

Source: Evolution

A theory, as the word is used in science, doesn't mean an unsupported speculation or hypothesis (the popular use of the word). A theory is, instead, a big idea that encompasses other ideas and hypotheses and weaves them into a coherent fabric. It is a mature, interconnected body of statements, based on reasoning and evidence, that explains a wide variety of observations. It is, in one of the definitions offered by the Oxford English Dictionary, “a scheme or system of ideas and statements held as an explanation of account of a group of ideas or phenomena; . . .a statement of what are known to be the general laws of something known or observed.” Thus atomic theory, quantum theory, and plate tectonic theory are not mere speculations or opinions, but strongly supported ideas that explain a great variety of phenomena. There are few theories in biology, and among them evolution is surely the most important.

© Copyright Original Source

This article from LiveScience also makes clear what theory means in the scientific sense:

Source: What is a Scientific Theory?

A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. If enough evidence accumulates to support a hypothesis, it moves to the next step—known as a theory—in the scientific method and becomes accepted as a valid explanation of a phenomenon.

When used in non-scientific context, the word “theory” implies that something is unproven or speculative. As used in science, however, a theory is an explanation or model based on observation, experimentation, and reasoning, especially one that has been tested and confirmed as a general principle helping to explain and predict natural phenomena.


Source

© Copyright Original Source

And as the prestigious National Academy of Sciences explained:

Source: Teaching About Evolution and the Nature of Science (1998)

Why isn't evolution called a law


Laws are generalizations that describe phenomena, whereas theories explain phenomena. For example, the laws of thermodynamics describe what will happen under certain circumstances; thermodynamics theories explain why these events occur.

Laws, like facts and theories, can change with better data. But theories do not develop into laws with the accumulation of evidence. Rather, theories are the goal of science.


Source

© Copyright Original Source

And before anyone gets their underwear all bunched up because I'm citing what they might call "pro-Darwin" sources perhaps these will help:

Source: American Heritage Dictionary

the·o·ry

1. A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.

© Copyright Original Source

Source: Dictionary.com

the·o·ry

1. a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena: Einstein's theory of relativity.

© Copyright Original Source

Source: Wikipedia: Scientific theory

A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method, and repeatedly confirmed through observation and experimentation.

© Copyright Original Source

In science theories explain facts. Without them facts are merely isolated data points with no relation to one another. Science without theory is useless since facts without explanatory principles are meaningless. This is why that in science theories occupy the highest tier of knowledge.

So when scientists use the word "theory" they don't mean a "guess," a "conjecture" or a "hunch" (like when someone says "I have a theory why Susie doesn't like broccoli"), but rather a well-substantiated, well-supported, well-documented explanation for our observations.

IOW, in science theory means an overarching framework that has been carefully constructed, based upon facts and encompassing many tested hypotheses, used to explain a variety of observations concerning the real world.

So when someone grumbles about how evolution is "just a theory" it isn't a valid objection to it, but rather a persuasive point in its favor.

[klaus54]

The anti-evolutionist's use of the wrong definition of "theory" is either

1) Out of ignorance OR

2) Intentional equivocation designed to confuse hoi polloi.

Throwing in the junk word "only" makes it even more misleading.

K54

[robrecht]

I miss Isaac Asimov ... Arthur C. Clarke, not to mention Kilgore Trout.

[Truthseeker]

rogue06, I misstated my thoughts. There are facts that we can be reasonably sure we know: I exist, I eat, I am typing a post, I expect to be abed in several hours, etc. The body of other "facts" that I think I "know" are far larger than the preceding one. The body of "facts" that I don't know that does not include the second one is far, far larger than it. Some scientific theories are in the 2nd body as far as my "knowledge" goes; other scientific theories are in the third one. Incidentally, I suspect Einstein's Theory of Relativity is not quite correct. Time dilation works a bit differently depending on what path the moving phenomena takes through space-time.

Observations--what is usually meant by scientific fact, right?--can be mistaken. Equipment, including one's own senses, can go blooie. Read up on the canals of Mars sometime.

One can indeed assess the probability of a proposition concerning some observation. "On the basis of the data, the null hypothesis is rejected. Phenomenon A follows Phenomenon B as sure as night follows day" [kidding]! But probabilities are not facts, unless we define a fact to be a proposition that we believe to be 0.99 probable. We can be mistaken, though how probable a "fact" is. People were claiming evidence for the canals of Mars or for 24 human chromosomes.

Didn't some people say that science can only attempt to determine probabilities, not facts?

[rogue06]

rogue06, I misstated my thoughts. There are facts that we can be reasonably sure we know: I exist, I eat, I am typing a post, I expect to be abed in several hours, etc. The body of other "facts" that I think I "know" are far larger than the preceding one. The body of "facts" that I don't know that does not include the second one is far, far larger than it. Some scientific theories are in the 2nd body as far as my "knowledge" goes; other scientific theories are in the third one. Incidentally, I suspect Einstein's Theory of Relativity is not quite correct. Time dilation works a bit differently depending on what path the moving phenomena takes through space-time.

Observations--what is usually meant by scientific fact, right?--can be mistaken. Equipment, including one's own senses, can go blooie. Read up on the canals of Mars sometime.

One can indeed assess the probability of a proposition concerning some observation. "On the basis of the data, the null hypothesis is rejected. Phenomenon A follows Phenomenon B as sure as night follows day" [kidding]! But probabilities are not facts, unless we define a fact to be a proposition that we believe to be 0.99 probable. We can be mistaken, though how probable a "fact" is. People were claiming evidence for the canals of Mars or for 24 human chromosomes.

Didn't some people say that science can only attempt to determine probabilities, not facts?

This is why most scientists try to avoid saying that they "proved" something because they understand that they don't know everything and will never know everything about a given subject. There is always the chance that something new might be discovered that overturns what we understood about something.

Still, there are some things that we've gathered so much evidence for, that it is so well attested, that it becomes increasingly unlikely to the point that the odds are infinitesimally small that it will be completely overturned. That does not mean that our understanding won't continue to be modified as new data becomes available.

[klaus54]

There's a similar distinction in two definitions of "proof".

1) Absolute certainty of a proposition, which is only possibly within the confines of any axiomatic system.

2) Data, evidence - verified and tangible measurements or observations.

Proof in science is the latter, proof in mathematics and logic is the former.

These definitions are readily conflated, usually innocently. But that conflation can lead to problems related to and as difficult to unwind as "Evolution is only a theory. It has no proof." There are at least four ways that can be interpreted, and (modulo "only) one way is correct.

K54

[Truthseeker]

Let me add this:
The correspondence between our perceptions and what we think is reality "out there" appears to vary from time to time. http://www.scientificamerican.com/ar...s-can-deceive/

[klaus54]

This does NOT apply to geology for sure. E.g., it's impossible to misread what one observes about the Appalachian cyclothems or shocked quartz from dozens of impact structures.

K54

P.S. And this link does not obviate the obvious distinctions in the dual definitions of both "theory" and "proof".

[klaus54]

Let me add this:
The correspondence between our perceptions and what we think is reality "out there" appears to vary from time to time. http://www.scientificamerican.com/ar...s-can-deceive/

This article deals with the psychological perception via the human eye and brain of certain everyday phenomena. It does NOT apply to careful observation by a multitude of trained people who agree on what is observed. A fortiori many of the observations are made via technology which is not subject to optical or perceptive illusions.

This is simply a worthless diversion from Rogue's thread starter.

K54

P.S. Of course we could be brains in jars and our sense of "reality" manipulated by aliens who are using us in some sort amusing video game.

Hey, maybe that's a tack that the Jorgian ilk can take? LOL

[OingoBoingo]

Apparently the lack of understanding by many of what a theory is in science leads some to talk about how things like evolution are "only a theory" and therefore dismiss it on those grounds.

A lot of this is based on what's being taught in American public school systems (or was being taught back when I went many decades ago). I was taught that when a scientist observes some phenomenon he creates a hypothesis. A hypothesis is a non-tested idea that explains what's being observed. A hypothesis is subject to change, and often is. The scientist takes a hypothesis and then rigorously tests it to see if holds water; if it needs to be tweaked, or if it can be disregarded altogether. If the hypothesis passes testing it becomes a theory. Even when a hypothesis passes initial testing and becomes a theory, its still subject to change, modification, or replacement as new data becomes available. A law is a theory that scientists are so certain of that's its considered fixed. It rarely if ever gets modified.

So basically what I was taught in school was that hypotheses and theories are in constant flux (hypotheses more than theories), and that laws are practically absolute.

To add confusion to all of this, the words "hypothesis" and "theory" are sometimes used synonymously in the common vernacular.

But, I have to say that when I hear people say that "evolution is just a theory", I don't believe they mean it in this common vernacular way that's synonymous with "hypothesis". I think they mean that, yeah, they realize that there's a whole lot of evidence for this particular scientific view, but that its not set in stone. If it was set in stone, it'd be a law!

Now that's obviously still a bad way to view the meaning of "theory", but its not as bad as thinking that a theory is just a wild guess, which is what a lot of evolutionists tend to think non-evolutionists mean when they say "evolution is just a theory". Non-evolutionists are usually a bit more clever than that (well...maybe not on this forum).

So yeah, blame it on our public school systems.

[rogue06]

Apparently the lack of understanding by many of what a theory is in science leads some to talk about how things like evolution are "only a theory" and therefore dismiss it on those grounds. But as the National Academy of Science explains, "theories are the goal of science" (see below) not, as the author and biochemist Isaac Asimov so eloquently put it, "something you dreamt up after being drunk all night."

Noted biologist Douglas J. Futuyma explains in his book "Evolution":

Source: Evolution

A theory, as the word is used in science, doesn't mean an unsupported speculation or hypothesis (the popular use of the word). A theory is, instead, a big idea that encompasses other ideas and hypotheses and weaves them into a coherent fabric. It is a mature, interconnected body of statements, based on reasoning and evidence, that explains a wide variety of observations. It is, in one of the definitions offered by the Oxford English Dictionary, “a scheme or system of ideas and statements held as an explanation of account of a group of ideas or phenomena; . . .a statement of what are known to be the general laws of something known or observed.” Thus atomic theory, quantum theory, and plate tectonic theory are not mere speculations or opinions, but strongly supported ideas that explain a great variety of phenomena. There are few theories in biology, and among them evolution is surely the most important.

© Copyright Original Source

This article from LiveScience also makes clear what theory means in the scientific sense:

Source: What is a Scientific Theory?

A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. If enough evidence accumulates to support a hypothesis, it moves to the next step—known as a theory—in the scientific method and becomes accepted as a valid explanation of a phenomenon.

When used in non-scientific context, the word “theory” implies that something is unproven or speculative. As used in science, however, a theory is an explanation or model based on observation, experimentation, and reasoning, especially one that has been tested and confirmed as a general principle helping to explain and predict natural phenomena.


Source

© Copyright Original Source

And as the prestigious National Academy of Sciences explained:

Source: Teaching About Evolution and the Nature of Science (1998)

Why isn't evolution called a law


Laws are generalizations that describe phenomena, whereas theories explain phenomena. For example, the laws of thermodynamics describe what will happen under certain circumstances; thermodynamics theories explain why these events occur.

Laws, like facts and theories, can change with better data. But theories do not develop into laws with the accumulation of evidence. Rather, theories are the goal of science.


Source

© Copyright Original Source

And before anyone gets their underwear all bunched up because I'm citing what they might call "pro-Darwin" sources perhaps these will help:

Source: American Heritage Dictionary

the·o·ry

1. A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.

© Copyright Original Source

Source: Dictionary.com

the·o·ry

1. a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena: Einstein's theory of relativity.

© Copyright Original Source

Source: Wikipedia: Scientific theory

A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method, and repeatedly confirmed through observation and experimentation.

© Copyright Original Source

In science theories explain facts. Without them facts are merely isolated data points with no relation to one another. Science without theory is useless since facts without explanatory principles are meaningless. This is why that in science theories occupy the highest tier of knowledge.

So when scientists use the word "theory" they don't mean a "guess," a "conjecture" or a "hunch" (like when someone says "I have a theory why Susie doesn't like broccoli"), but rather a well-substantiated, well-supported, well-documented explanation for our observations.

IOW, in science theory means an overarching framework that has been carefully constructed, based upon facts and encompassing many tested hypotheses, used to explain a variety of observations concerning the real world.

So when someone grumbles about how evolution is "just a theory" it isn't a valid objection to it, but rather a persuasive point in its favor.

A nice addition that I found in an article by James J. Krupa, a biology professor at the University of Kentucky wrt the Theory of Evolution:

Source: Defending Darwin

In science, something can be both theory and fact. We know the existence of pathogens is a fact; germ theory provides testable explanations concerning the nature of disease. We know the existence of cells is a fact and that cell theory provides testable explanations of how cells function. Similarly, we know evolution is a fact and that evolutionary theories explain biological patterns and mechanisms. The late Stephen Jay Gould said it best: “Evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world’s data. Theories are structures of ideas that explain and interpret facts.”

Theory is the most powerful and important tool science has, but nonscientists have perverted and diluted the word to mean a hunch, notion, or idea. Thus, all too many people interpret the phrase evolutionary theory to mean evolutionary hunch. Not surprisingly, I spend the first week of class differentiating theory from fact, as well as defining other critical terms.


Source

© Copyright Original Source

[sfs1]

My only problem with these official definitions of what "theory" means in science is that I suspect they're a bunch of hooey. Has anyone seen a study of how scientists actually use the word "theory", and whether they actually conform to these definitions? In my experience, scientists mostly describe broad, well-supported explanatory frameworks as theories for historical reasons. In contemporary usage, "theory" is all over the map. Endosymbiotic theory and the neutral and nearly neutral theories of evolution were all called "theories" long before they were widely accepted or well supported, and they still don't really have the breadth that the definition of "theory" might suggest. In particle physics, heavy quark effective theory and lattice gauge theory were mathematical approaches for doing approximate calculations, calculations that couldn't be done in the full theory, which isn't called a theory -- it's the Standard Model. Technicolor and supersymmetric models are often called theories, even though they have zero experimental support.

So do any scientists actually use the word "theory" in the way that's proposed? How do other fields use the word?

[shunyadragon]

My only problem with these official definitions of what "theory" means in science is that I suspect they're a bunch of hooey.

Your suspicions do not justify our question the scientific concepts of theory.

Has anyone seen a study of how scientists actually use the word "theory", and whether they actually conform to these definitions? In my experience, scientists mostly describe broad, well-supported explanatory frameworks as theories for historical reasons. In contemporary usage, "theory" is all over the map. Endosymbiotic theory and the neutral and nearly neutral theories of evolution were all called "theories" long before they were widely accepted or well supported, and they still don't really have the breadth that the definition of "theory" might suggest.

Your all over the place and not coherent concerning what theory means in terms of science. Do you accept the science of evolution?

In particle physics, heavy quark effective theory and lattice gauge theory were mathematical approaches for doing approximate calculations, calculations that couldn't be done in the full theory, which isn't called a theory -- it's the Standard Model.

The standard model is a model not a theory

Technicolor and supersymmetric models are often called theories, even though they have zero experimental support.

Sometimes called, ah . . . no.

So do any scientists actually use the word "theory" in the way that's proposed? How do other fields use the word?

Science is the issue here, and yes scientist use and know perfectly well what 'theory' means.

[sfs1]

Your suspicions do not justify our question the scientific concepts of theory.

Why ever not? Scientists question things.

Your all over the place and not coherent concerning what theory means in terms of science.

Exactly my point. What the word "theory" means in science is actually all over the map, not the tidy meanings that are sometimes offered.

Do you accept the science of evolution?

Yes, although I have no idea what that has to do with anything.

The standard model is a model not a theory

Which of the definitions previously offered does it not fit? It's a 'big idea that encompasses other ideas and hypotheses and weaves them into a coherent fabric. It is a mature, interconnected body of statements, based on reasoning and evidence, that explains a wide variety of observations. It is, in one of the definitions offered by the Oxford English Dictionary, “a scheme or system of ideas and statements held as an explanation of account of a group of ideas or phenomena; . . .a statement of what are known to be the general laws of something known or observed.”'

Science is the issue here, and yes scientist use and know perfectly well what 'theory' means.

I asked for evidence of this usage, not bare assertion.

[shunyadragon]

Why ever not? Scientists question things.

True, they propose a hypothesis, and test and falsify the hypothesis with scientific methods, and the result may be called a theory or a hypothesis that supports a theory. That's how science works in the real world. The hypothesis or theory fails or succeeds based on the evidence.

Exactly my point. What the word "theory" means in science is actually all over the map, not the tidy meanings that are sometimes offered.

No, not all over the map. You are all over the map without a coherent argument.

Yes, although I have no idea what that has to do with anything.

Trying to establish your agenda and negative view towards science. Your avoiding the question.

Which of the definitions previously offered does it not fit? It's a 'big idea that encompasses other ideas and hypotheses and weaves them into a coherent fabric. It is a mature, interconnected body of statements, based on reasoning and evidence, that explains a wide variety of observations.

Big Idea? Theories most often start with small ideas and hypothesis, which are then tested by scientific methods. Not meaningful. Hypothesis are proposed usually based on some evidence. The hypothesis is tested and falsified by objective scientific methods, and often combined math. By the way, not 'proven' in science. The theories may by applied to models, and theories that apply to the models are further tested and falsified to determine if the models are sound.

It is, in one of the definitions offered by the Oxford English Dictionary, “a scheme or system of ideas and statements held as an explanation of account of a group of ideas or phenomena; . . .a statement of what are known to be the general laws of something known or observed.”'

To vague to be real in the scientific application of the meaning of a theory. Let's stick with the specific meanings and uses of theory in science as I described above.

I asked for evidence of this usage, not bare assertion.

Not a bare assertion at all. Scientist know what theory means and use it specifically as I described it above.