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theory

theory

(OP)
Many people post here questioning the use or misuse of a word. A lot of the time I will look up the word and find the postor's use and the questioned use are both valid. Some of these multiple definitions, though, make our language imprecise. "Troop" comes to mind. Here's another. In scientific circles, "theory" is something that is well established. But in common usage, it is a synonym for "hypothesis," or sometimes "guess." This usage is so wide spread that the dictionary endorses it. Even scientists will sometimes use the common meaning. It has come to the point where some are advocating the idea that an untestable wild donkey guess is just as valid as real scientific theory that has a century of testing behind it. After all, "it's just a theory." I'd like to suggest, that as technical folk, we watch our usage of the word. Let's use "hypothesis" when it fits. Maybe we can reverse the trend. Okay, maybe I'm dreaming. http://wilstar.com/theories.htm

RE: theory

Interesting.  So when someone says, "evolution is just a theory," they are actually saying it is well established!

DaveAtkins

RE: theory

2
It always irks me to hear someone say "such-and-such is JUST a theory", as if this somehow invalidates it. From a scientific point of view, "a theory" is as good as it gets. You can never "prove" a theory is true, only that a theory fits all observed phenomena so far. However, every theory is always subject to the risk that a single contrary observation can show that the theory is incomplete or even incorrect. (E.g. objects fall to earth because the earth is the natural centre of the universe => Newton's Theory of Gravitation => Einstein's Theory of Relativity => Quantum Mechanics => String Theory => "Theory of Everything" => ???) Note that even though Newton's Theory has been well and truly shown to be incomplete, it still holds "true" for pretty well all everyday applications, and is still a useful theory, as longs as its limitations are understood.

A hypothesis can be no more than a conjecture, which seems plausible in that it appears to fit the observed facts, but has not been "fleshed out" to be testable by experiment.

In scientific usage, a theory goes further than a hypothesis, in that it makes specific predictions of as-yet unobserved phenomena, which can be tested by experiment. If the experiment is conducted, and fits the prediction, this supports the theory, but does not "prove" it. You can never "prove" a theory is true, but you can immediately disprove it by obtaining a repeatable negative result.

Typically, the process is that some phenomenon will be observed which does not fully fit the existing theory of the day, thus calling into question some or all of the validity of the existing theory. (e.g. the discovery that dinosaur bones appear to be many millions of years old, when the Bible tells us that God created the universe only some thousands of years ago, in pretty much its current form. It seems that the exiting biblical explanations of Creation don't fit all the observed facts.) Someone will make a hypothesis that better fits the observed facts (millions of years ago, there were entirely different species roaming the earth which have somehow evolved into the current observed forms), but this hypothesis may not make any specific prediction as to how this all came about. People will work on the hypothesis to develop a fully-fledged theory (random mutations can be inherited by a process of natural selection, such that any mutation which provides a survival advantage, no matter how small, is more likely to be retained than mutations which do not provide such an advantage. Over time, new species are evolved.)

The theory of evolution by natural selection qualifies as a true theory, not just a conjecture or hypothesis, because it provides an explanation for the mechanism of the development of species, and is testable by experiment and observation. As yet, no-one has found a single instance which contradicts the basics of the theory of evolution.

So-called "Intelligent Design" (a.k.a. "Creation Science") does NOT qualify as a scientific theory, and has no place in science education, because it is based on faith and a simple assertion that life is too complex to have evolved by chance, so an intelligent creator must have been involved. Importantly, it makes no predictions which are testable by experiment or observation, so it is not Science.

While Science cannot disprove "Intelligent design" (precisely because it makes no predictions which can be tested), the Theory of Evolution has stood up to test and observation for well over 100 years, and is still looking rock solid!

hypothesis: a proposition proposed as an explanation for the occurrence of some phenomenon, either as a simple conjecture, or accepted as highly probable in the light of established facts

theory: a coherent set of propositions used as principles of explanation of a class of phenomena, which makes specific predictions which can be tested by experiment or observation

RE: theory


JulianHardy's definition of theory suits the scientific approach, although others may add that, in general, the explained phenomena are inferred from more "primitive" phenomena in less need of explanation.

But there are other colloquial definitions that include speculation, hypothesis, belief, policy, conjecture, etc., as can be found in english dictionaries.

RE: theory

I think some of the bad press the word “theory” has received comes from scientists extrapolating or expanding from the original theory and presenting it as the original theory.

For example:  “The theory of evolution proves that every living thing on earth evolved from a single cell organism.”  No it does not.  

You may have a deep rooted belief that this is true but it is not the theory of evolution.  You may believe that life was started by cosmic dust from comets, steam vents under the sea, alien intervention or intelligent design.  None of these contradict the theory of evolution.

When scientists tie the validity of their own hypotheses to the theory of evolution or any other theory and the hypotheses get disproved every other year the public is taught the worth of theories.  

I do not think there is any hope of scientists not extrapolating on theories and presenting it has the original theory.  It is just too easy and people are lazy.

Barry1961        

RE: theory

I disagree with julianhardy that theories can't be proven....assuming your usage of "theory" is identical to "theorem".

I recall from  high school that theorums were first proposed, then sometimes proven (not all theorems were proven to be true, and some cannot be proven true or false).

From my available dictionaries, a theorem is essential a sub-set of theory, one that can be deduced from other formula, facts, or propositions.  

ALso, a theory is a synonym for hypothesis.

RE: theory

(OP)
Before it was proven, it was a postulate. After proof it became a theorem. But the proof always depended on one or more underlying assumptions. Similarly in science, absolute fact is unattainable. And in science, theory is not a synonym for hypothesis. They are, however, synonyms in common use, which brings us to the confusion of today.

RE: theory

I was taught that a hypothesis becomes a theory through tests with repeated expected outcome.  A theory can become law once the expected outcome is inevitable.

Although colloquially theory and hypothesis are used as synonyms, they are different and I place more weight on theory.

In addition, there are various subjects where these words apply such as in Mathematics, Physics, Nature, Economics, Human Behavior, etc.  Laws of Mathematics may be easiest to establish while hypothesis of human behavior can be easily disproved.

RE: theory

(OP)
Please see my link above to see the difference between law and theory. Theory is actually a higher order than law. Law is just an observation, while theory answers why.

RE: theory

Thanks for reminding me to go to the link.  It was informative.

I can see that theory explains a more complex phenomena than law.  But shouldn't law be higher order than theory in that it is more difficult to disprove?

If higher order simply means complexity, I agree with you.

RE: theory

this discussion is central to the branch of philosophy called epistemology... which is the science that studies science... there are literally whole libraries dedicated to the subject... it will be difficult to encapsulate in just a few postings all the centuries long discussions about the subject...

having said so... i do agree that popular use has mixed up the use of hypothesis and thesis...
nevertheless, it will be a social faux-pas or a career-decission move to face anyone in a conversation with something like this:
- sorry, but you are calling a theory what in fact is only a hypothesis.

which reminds me of the Dilbert's salary theorem...
we know that:
knowledge is power K = P
time is money T = $

from physics... P = W/T power is work per unit time

so...
K = W/$

then...

$ = W/K

thus:
given that you can only work so many hours a week... W has a maximum, and so does your salary ($)

but...

knowledge... the more you know the less money you make no matter how hard you work...
conversely... the less you know the higher your salary...

even if you do no work and know nothing... you can still be making ends meet thanks to L'Hospital

so if you show this to somebody that does not understand this demonstration... annoyingly, his/her salary is surely pretty nice.

saludos.
a.

RE: theory


Sometimes W = f (K), as when working as a consultant, in which case the application of L'Hopital's rule becomes more difficult. No es cierto ?

RE: theory

mshimko,

Gödel's incompleteness theorem (paraphrased) states that for any consistent formal system (e.g. any area of scientific study) there exist certain propositions which may be true, but which cannot be proven within the formal constraints of the system.

More generally, any formal system must have certain statements which are taken as being self-evidently true (these are known as Axioms), but which cannot be proven to be true within the constraints of that system.

Referring back to your high school geometry, you may remember Euclid's Axioms - these are accepted as "fact", but cannot in fact be proven within Euclidean geometry.

A-1 Every two points lie on exactly one line.
A-2 Any line segment with given endpoints may be continued in either direction.
A-3 It is possible to construct a circle with any point as its centre and with a radius of any length.  (This implies that there is neither an upper nor lower limit to distance. In-other-words, any distance, no matter how large can always be increased, and any distance, no matter how small can always be divided.)
A-4 If two lines cross such that a pair of adjacent angles are congruent, then each of these angles are also congruent to any other angle formed in the same way.
A-5 Given a line l and a point not on l, there is one and only one line which contains the point, and is parallel to l.

RE: theory

There are some planar geometry postulates that can be added to the list by JulianHardy:

1. Two straight lines cross at only one point
2. Only one perpendicular exits trough a point on a line
3. Only one perpendicular exists through a point not on a line

Then there are the famous equality axioms that serve as premises to many theoretical disciplines:

1. Reflexive: any quantity is equal to itself
2. Transitive: two quantities equal to a third, are equal to each other
3. Substitution: if two quantities are equal, then one can replace the other in any expression without changing the results
4. Partition: a quantity is equal to the sum of its parts.
5. Rate: INPUT-OUTPUT = ACCUMULATION (or DEPLETION)

Observation or experimental work -used as base for theories or laws- often precede theoretical confirmation.

Take, for example, the 20 years or so that took Kepler to discover his third law: the squares of the periods T of revolution of the planets about the sun are proportional to the cubes of their average distances D from the sun.

He must have studied long and hard before discovering the constancy of the ratio T2/D3.

Only a few years later, Newton derived Kepler's laws by the use of calculus, showing that they hold for any orbital system that obeys the laws of motion and gravitation.

RE: theory

L'Hospital, Guillaume de (1661-1704)  
French mathematician who, at age 15, solved a difficult problem about cycloids  posed by Pascal. He published the first book ever on differential calculus,  L'Analyse des Infiniment Petits pour l'Intelligence des Lignes Courbes (1696). In this book, l'Hospital included l'Hospital's rule.  l'Hospital's name is commonly seen spelled both "l'Hospital" and "l'Hôpital" (e.g., Maurer 1981, p. 426), the two being equivalent in French spelling.

http://scienceworld.wolfram.com/biography/LHospital.html

saludos.
a.

RE: theory


Aceptado y confirmado.

RE: theory

However we select from nature a complex [of phenomena] using the criterion of simplicity, in no case will its theoretical treatment turn out to be forever appropriate . . . . I do not doubt that the day will come when general relativity, too, will have to yield to another one, for reasons which at present we do not yet surmise. I believe that this process of deepening theory has no limits.
     Albert Einstein



 

RE: theory

JulianHardy, for Godel's theorem to apply the system has to be sufficiently powerful, as well as consistent and formal, and it doesn't mean axioms, it is talking about other statements.

I don't think there are any undecidable propositions in simple arithmetic, for example. If you accept the axioms then you get a complete, but very limited, formal system, that cannot say anything very interesting.

And, oddly enough, the test for whether a system is sufficiently powerful for Godel's Theorem to apply, is that it must be possible to state Godel's Theorem in that system.

Which is about as neat a piece of recursion as I have ever seen.



Cheers

Greg Locock

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