# Confusion about laws versus theories. **URL:** \ **Category:** Factual Questions\ **Created:** [April 14, 2003, 10:03pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739 "2003-04-14T22:03:54Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![kimera](https://avatars.discourse-cdn.com/v4/letter/k/f0a364/32.png) [@kimera](https://boards.straightdope.com/u/kimera)\ **Post date:** [April 14, 2003, 10:03pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/1 "2003-04-14T22:03:54Z")
So there was a discussion about evolution on another board and the whole “law versus theory” topic came up. I noticed that various sites seemed to have different opinions about what is a law versus what is a theory, so come to you all to sort out the mess. An example, [this[/place] place says that the " theory of relativity" should be instead considered the “fact of relativity”. Yet, [url=“http://www.sciam.com/article.cfm?articleID=000D4FEC-7D5B-1D07-8E49809EC588EEDF&catID=2”]this](http://www.facsnet.org/tools/sci_tech/methods.php3) says that > [@](#): > > No amount of validation changes a theory into a law, which is a descriptive generalization about nature. . So I am confused. Can a theory be made into a law? Finally, what is the difference between the law of gravity and the theory of gravity? Is there one? I have this feeling that I am just being completely dense and missing something that should be perfectly clear to me. It’s been decades since I have had a science class, so I would appreciate it if you explain things so they are easy to understand. Thanks for your patience. ---
**Author:** ![kimera](https://avatars.discourse-cdn.com/v4/letter/k/f0a364/32.png) [@kimera](https://boards.straightdope.com/u/kimera)\ **Post date:** [April 14, 2003, 10:07pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/2 "2003-04-14T22:07:44Z")
The second link is [http://www.sciam.com/article.cfm?ar...588EEDF&catID=2](http://www.sciam.com/article.cfm?ar...588EEDF&catID=2) ---
**Author:** ![Meatros](https://avatars.discourse-cdn.com/v4/letter/m/b4bc9f/32.png) [@Meatros](https://boards.straightdope.com/u/Meatros)\ **Post date:** [April 14, 2003, 10:20pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/3 "2003-04-14T22:20:59Z")
Here’s talk origins idea of [a theory](http://www.talkorigins.org/faqs/evolution-fact.html) Here’s another [one.](http://www.talkorigins.org/faqs/faq-misconceptions.html#proof) > [@](#): > > First, we should clarify what “evolution” means. Like so many other words, it has more than one meaning. Its strict biological definition is “a change in allele frequencies over time.” By that definition, evolution is an indisputable fact. Most people seem to associate the word “evolution” mainly with common descent, the theory that all life arose from one common ancestor. Many people believe that there is enough evidence to call this a fact, too. However, common descent is still not the theory of evolution, but just a fraction of it (and a part of several quite different theories as well). The theory of evolution not only says that life evolved, it also includes mechanisms, like mutations, natural selection, and genetic drift, which go a long way towards explaining how life evolved. Basically a theory involves a specific thing while a law encompasses a lot of ground. Law- What goes up comes down. A theory would be something to the effect of the precise pull that the sun has on the earth. Or at least that’s how I understand it. ---
**Author:** ![Joe\_Random](https://avatars.discourse-cdn.com/v4/letter/j/e8c25b/32.png) [@Joe\_Random](https://boards.straightdope.com/u/Joe_Random)\ **Post date:** [April 14, 2003, 10:26pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/4 "2003-04-14T22:26:04Z")
> [@](#): > > \*Originally posted by ava \* > **Can a theory be made into a law?** No. A theory and a law are two totally different things. A law is a description of what is observed. A theory is a description of how that law works. > [@](#): > > **Finally, what is the difference between the law of gravity and the theory of gravity? Is there one?** The law of gravity simply states the observable relationship between mass, distance, and gravitational force. The _theory_ of gravity attempts to explain how the law of gravity actually works. If reference to the original topic, there is a sort of law of evolution. The problem is, it’s usually referred to simply as “evolution”, or sometimes the “fact of evolution”. Evolution happens, and has been observed in limited cases. It can also be easilly extrapolated from available evidence for larger cases. The _theory_ of evolution attempts to explain how evolution actually works. ---
**Author:** ![PhuQan\_G\_Nyus](https://avatars.discourse-cdn.com/v4/letter/p/f14d63/32.png) [@PhuQan\_G\_Nyus](https://boards.straightdope.com/u/PhuQan_G_Nyus)\ **Post date:** [April 14, 2003, 10:51pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/5 "2003-04-14T22:51:20Z")
a law is a rule that matter or whatever seems to obey regardless of the explanation. In other words the laws of gravity dictate that what goes up must come down. The “theory” of gravity attempts to explain WHY such a thing occurs. Theory can only become law when it can be proven correct. For instance we can theorize that mars has water on it and we can give all kinds of evidence to defend our views. It will stay a theory though until such time as water can be proven. Now we know that with gravity what goes up must come down. That is essentially a “law” that is observable and provable. Now the theory is that all mass attracts other mass and that gravity represents a “warping” of space. We can not see this warping nor can we really prove there is such a thing as gravity we can only observe the laws in action and theorize the cause. ---
**Author:** ![Joe\_Random](https://avatars.discourse-cdn.com/v4/letter/j/e8c25b/32.png) [@Joe\_Random](https://boards.straightdope.com/u/Joe_Random)\ **Post date:** [April 14, 2003, 11:02pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/6 "2003-04-14T23:02:59Z")
> [@](#): > > \*Originally posted by PhuQan G Nyus \* > **Theory can only become law when it can be proven correct.** Wrong on two different issues. 1. Theories _explain_ laws. Theories never, ever _become_ laws. 2. Sience never proves _anything_. Only math has proofs. > [@](#): > > **For instance we can theorize that mars has water on it** Another common misconception. That’s called a _hypothesis_, not a theory. The definition of “theory” that is used by people in everyday conversation is much different than how the word is used in science. > [@](#): > > **Now we know that with gravity what goes up must come down.** “Must” is a little too strong. Just exceed escape velocity, and it ain’t comin’ back down. > [@](#): > > **Now the theory is that all mass attracts other mass and that gravity represents a “warping” of space.** No, the _law_ is that all mass attracts other mass. The “warping of space” is the theory that attempts to explain the law. ---
**Author:** ![Meatros](https://avatars.discourse-cdn.com/v4/letter/m/b4bc9f/32.png) [@Meatros](https://boards.straightdope.com/u/Meatros)\ **Post date:** [April 15, 2003, 3:53am UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/7 "2003-04-15T03:53:02Z")
I agree with Joe, who said the difference between a law and theory a little more…coherently than I did :D. **PhuQan G Nyus** -as **Joe** said laws never become theories, in fact that’s one of the sticking points for creationists that I’ve found. The idea is that since theory is (in the popular vernacular), is basically a ‘guess’ then it shouldn’t be regarded as correct. This is actually not the case. A scientific theory is a lot more then a guess, as is a hypothesis (which is an educated guess). ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [April 15, 2003, 3:55am UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/8 "2003-04-15T03:55:43Z")
All it really means is that scientists began to lose some of their hubris. All of the “Laws” of science are pre-1900. After that, I don’t believe that any new “Laws” have been stated. (The last ones were probably Maxwell’s Laws of Electromagnetism.) The first statement we call a "Theory"entered the public consciousness after 1859 when Darwin’s work began being referred to as the Theory of Evolution . Since that time we’ve also had the Theory of Relativity and Quantum Mechanical Theory. The changeover is as much sociological as anything else. Scientists had a different conception of their place in society and looked at their work as descriptions of the way the world worked rather than as final explanations of it. Even so, there just aren’t that many capital “T” Theories, and there were only a few capital “L” Laws. I’m not even sure that any of the individual discovers of the Laws and Theories were the ones responsble for labeling them Laws and Theories. Others in their cultures took these and used them as they saw appropriate in their day. However, there is still some use of the older term, in that physics is considered to consist of universal laws that apply to any place and time (outside singularities). But these are small “l” laws rather than capital "L’ Laws. ---
**Author:** ![Agback](https://avatars.discourse-cdn.com/v4/letter/a/977dab/32.png) [@Agback](https://boards.straightdope.com/u/Agback)\ **Post date:** [April 15, 2003, 6:22am UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/9 "2003-04-15T06:22:32Z")
G’day Consider this. Gravity follows an inverse square law. It does not follow an inverse cube law. But we don’t say that newton’s Theory of Universal Gravitation is a law and that inverse-cube gravity is ‘only a theory’. “Law” has been used several different ways in science over the years. When Malthus wrote that population rises according to a geometrical law he meant that (as we would put it now) that it tends to rise as an exponential function of time, nothing more. Lots of ‘laws’ in science and maths, especially older ones are what we would call ‘functions’ now. Some others are verbal formulations in a more general sense, such as the ‘Laws’ of Thermodynamics. The Laws of the Thermodynamics now have the status of having been well-tested and almost universally accepted–but they were called ‘laws’ before that was true. Meanwhile, a theory is a different class of thing. A theory, like the Theory of Universal Gravitation, Atomic Theory, the Molecular Theory of Gases, Number Theory, Quantum Theory, the Theory of Special Relativity, the Theory of General Relativity, Galois Theory, the Germ Theory of Disease, etc, etc, is a _coherent body_ of axioms and reasoning, especially one that provides a unified explanation for diverse phenomena. On occasions, rival theories have attempted to explain the same phenomena–for example the Theory of the Humours and the Germ Theory of Disease, or the Wave Theory of Light and the Corpuscular Theory of Light. In some such cases one of the rivals makes a testable prediction that is not borne out by experiment, or fails to predict something that the other predicts and that is observed. But it is not the tentative nature of the body explanations that makes it a theory: all propositions in science are, formally speaking, tentative. Rather, it is the coherence and ability to generate predictions and explanations that makes a theory. Regards, Agback ---
**Author:** ![Agback](https://avatars.discourse-cdn.com/v4/letter/a/977dab/32.png) [@Agback](https://boards.straightdope.com/u/Agback)\ **Post date:** [April 15, 2003, 6:26am UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/10 "2003-04-15T06:26:24Z")
G’day One more thing: Number Theory includes propositions that have been proven to be true: these are called “theorems” and “lemmas”, not “laws”. Number Theory also includes propositions that have not been proven, and may never be. They are called “conjectures”, not “theories”. Regards, Agback ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [April 15, 2003, 6:34am UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/11 "2003-04-15T06:34:02Z")
Previous related threads: [What is the proof of the law of inertia?](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=167530) [When does something become scientific law?](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=83683) My take from the most recent thread: > [@](#): > > \*Originally posted by robby \* > You cannot “prove” physical laws nor theories. To do so would require observation and/or experimental verification over all time and space. > > A physical “law” is simply a summary of observations. > > A theory is an explanation of one or more observation(s). > > To use a chemistry example, it has been observed that a given chemical compound always contains the same proportion by mass of each of its constituent elements. After this was observed to be true for every chemical compound so analyzed, the observation was deemed important enough to be summarized as the “Law of Definite Proportions.” > > Soon thereafter, Dalton proposed an explanation for why the aforementioned law was always observed to hold true. His theory is called “Dalton’s Atomic Theory.” The theory hypothesizes that all elements are made up of atoms that combine to form elements. > [@](#): > > \*Originally posted by robby \* > …as I stated in my last post, you cannot prove physical laws. You can only gather more observations that support a law and do not disprove it. > > While laws cannot be proved, they can be disproved. One example is the “Law of Conservation of Mass.” This law was experimentally invalidated with the advent of nuclear physics. In short, a “law” summarizes _what_ happens, while a theory attempts to explain _why_ something happens. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [April 15, 2003, 6:51am UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/12 "2003-04-15T06:51:15Z")
> [@](#): > > \*Originally posted by Agback \* > \*\*…Number Theory includes propositions that have been proven to be true: these are called “theorems” and “lemmas”, not “laws”. > > Number Theory also includes propositions that have not been proven, and may never be. They are called “conjectures”, not “theories”.\*\* **Agback** , no offense intended whatsoever, but I wouldn’t drag mathematics into this discussion. The foundation of the physical sciences is experimental observation, a key part of the scientific method. All physical laws and theories must agree with what is actually observed and measured. In math, on the other hand, the foundation is a set of assumptions (postulates?) which leads to everything else (or so I am lead to believe, but IANAM\*). Physical observation never comes into it. For example, Euclidean geometry is based on Euclid’s five postulates presented in his _Elements_–physical observations of the universe are irrelevant. These two very different foundations lead to differing views of laws and theories. For one thing, mathematicians prove things. Physical scientists do not. [sub]\*mathematician[/sub] ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [April 15, 2003, 2:37pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/13 "2003-04-15T14:37:47Z")
I see it another way & quite simple that: a theory is always trying to be disproven. ---
**Author:** ![I\_Brian](https://avatars.discourse-cdn.com/v4/letter/i/c89c15/32.png) [@I\_Brian](https://boards.straightdope.com/u/I_Brian)\ **Post date:** [April 15, 2003, 3:00pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/14 "2003-04-15T15:00:28Z")
As Stephen Hawking made an especial point of in “A Brief History of Time”, science does not deal with facts and certainties, only probabilities. ---
**Author:** ![Barbarian](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Barbarian](https://boards.straightdope.com/u/Barbarian)\ **Post date:** [April 15, 2003, 6:12pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/15 "2003-04-15T18:12:39Z")
But for the layperson, a scientific probability or theory may as well be fact. I chalk it up to scientists talking a different language than regular people. ---
**Author:** ![Billdo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/billdo/32/315_2.png) [@Billdo](https://boards.straightdope.com/u/Billdo)\ **Post date:** [April 15, 2003, 6:34pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/16 "2003-04-15T18:34:06Z")
I have a question about some “Laws” that have been “disproven” or at least found to only apply in limited situations. I’m thinking of, for instance, Newton’s Laws of Motion. They’re accurate for commonly observable physical interactions here on Earth, but when we get into relativistic speeds, for example, they become inaccurate. Put another way, the Theory of Relativity has disproven Newton’s Laws. Taken to the extreme, we can calculate the relativistic component of a slow-speed collision between two marbles, even though that component would be well below the threshhold of what we can measure about the collision. Although linguistic inertia will probably mean that Newton’s Laws will remain described as “Laws,” what how would we describe them today if we were naming them for the first time? ---
**Author:** ![andymurph64](https://avatars.discourse-cdn.com/v4/letter/a/a88e57/32.png) [@andymurph64](https://boards.straightdope.com/u/andymurph64)\ **Post date:** [April 15, 2003, 7:14pm UTC](https://boards.straightdope.com/t/confusion-about-laws-versus-theories/168739/17 "2003-04-15T19:14:57Z")
Related, The easier it would be to disprove a theory, the more powerful it is. Easy to disprove but hasn’t yet == powerful. The harder it is to disprove a theory the less powerful it is. Nearly impossible to disprove == worthless. Something my wife has trouble understanding… 😉 as she likes psychics, ghosts, etc.