Why do scientists call evolution a "theory"?

[Jupiter60]

TL;DR

"just a theory"

Why do scientists refer to evolution as a theory which leads to the argument that evolution is "just a theory"? Why don't they use a less confusing word?

 

[hutchphd]

Because it is not wise to allow fools and miscreants to dictate one's allowed speech. We routinely say Electromagnetic Theory for instance. Or Quantum Theory
You should feel free to suggest something more helpful and argue it be included in the lexicon instead, but it is not clear to me this serves a useful purpose. Science is, to a large degree, about rejecting dogma.

.

 

[phinds]

To add to what @hutchphd said, back in Newton's day science discoveries were considered more concrete and unlikely to change. So Newton's LAW of Gravity would today be called Newton's Theory of Gravity, just as the more recent, and more accurate theory is called Einstein's Theory of Relativity. We just don't call things Laws any more even when they are not expected change, except perhaps by being expanded to include domains that were not originally there (such as the expansion from Newton to Einstein).

People who say that something is "just a theory" in a pejorative way are simply scientifically ignorant.

 

[jim mcnamara]

It extends into a lot of other words like belief, coincidence. Helen Quinn takes a very different tack from @hutchphd - she claims we know better and should find ways to communicate
see: https://ned.ipac.caltech.edu/level5/March07/Quinn/Quinn.html

 

[phinds]

People who say that something is "just a theory" in a pejorative way are simply scientifically ignorant.

And I would add to that ... almost always someone who acts like that does NOT want to be educated, so it's pointless to even have a discussion with them.

 

[hutchphd]

It extends into a lot of other words like belief, coincidence. Helen Quinn takes a very different tack from @hutchphd - she claims we know better and should find ways to communicate
see: https://ned.ipac.caltech.edu/level5/March07/Quinn/Quinn.html

I respectfully yet emphatically disagree with her emphasis. I see her recommendation as a plea to reduce scientific "fact" (what is that?) to a dogma that can be easilly swallowed. This approach is intrinsically anti-scientific and therefore eventually counterproductive and in fact dangerous.
The antivaxxers criticised Dr Fauci most vehemently for changing his mind when the evidence required. One is not allowed to change dogma.

 

[StevieTNZ]

The word 'theory' in a scientific context has a different meaning than the ordinary definition of the word.

 

[Godot_]

Because it still is a theory, albeit one, where we can prove all the elements and several steps in small scales in vitro. Or observe evolution in work in nature.

But alas, we didn't have an observer in place when the first ribozymes formed so we can't prove it from A to Z. So it's a theory.

However, "theory" in the science world means that there is a significant body of evidence to back it up - before that it'd be "hypothesis". As would be the "theory" in the "Evolution's just a theory!"-people's terminology. Which, BTW, I love to counter with "...and the creation story is just hearsay from five thousand years ago. I place my bet where I see data backing it up."

To add to what @hutchphd said, back in Newton's day science discoveries were considered more concrete and unlikely to change. So Newton's LAW of Gravity would today be called Newton's Theory of Gravity, [...}.

Newton's Law of Gravity is a different story: It's a mathematical formula, that can be observed, measured, quantified, verified, and validated within its limits. So the term "law" is somewhat appropriate. This isn't just about its age... ...many newer phenomena still get the law treatment. But like Newton's law, these only pertains to one small aspect, and can be quantitatively verified and validated. Like Avogadro's law, the Boltzmann law, Hagen-Poiseulle-Law etc. etc.

These are most often referred to as ___ equation, too, but they're, within their known and often defined limits, true and testable, so the term law is somewhat applicable, and sometimes still in use in some languages, like my native German. In e.g. the case of Avogadro's law, those limits are that the whole thing must remain in the gaseous phase, there must not be chemical reactions, etc. etc. But as long as you stay within these bounds, it can be quantitatively verified, over and over again.

The theory of relativity, however, is of the grandest scope, just like the theory of evolution. So no scientist would consider calling it a law...

In molecular biology for example, you won't find many "laws". Even the "universal genetic code" isn't universal - there are quite a bunch of exceptions. "General" or "most common genetic code" would be a better term... ...so it's mostly just called the genetic code, without any overbearing qualifiers. But in general, most things MolBiol are a) to some extent "wobbly", b) thus rarely work 100% of the time, and c) are often initially inferred via somewhat arcane steps. Which sometimes means that they are later found to be experimental artifacts. So the term mostly used here is ___ model.

 

[Godot_]

On a slight sidestep from the original OP topic, here's one pretty awesome for-show-experiment demonstrating and illustrating the concept of evolution:



Enjoy the ride...

 

[pinball1970]

Summary: "just a theory"

Why do scientists refer to evolution as a theory which leads to the argument that evolution is "just a theory"? Why don't they use a less confusing word?

Richard Dawkins dedicated the first chapter to this problem in his book 'the greatest show on earth.'

https://publicism.info/nature/show/2.html

In short, it is not a problem for kids willing to learn about Science if it is explained properly, so why should scientists change recognized terminology?

If you talking to people who really do not want to be educated as @phinds said you are wasting your time anyway.

Certain groups want to point out a flaw wrt TOE to reinforce their own belief which may be nothing at all to do with science.

 

[jack action]

When you look in the dictionary, it's pretty clear what the word "theory" means, depending on the context:

Noun​

theory (countable and uncountable, plural theories)

1. A description of an event or system that is considered to be accurate.
2. (sciences) A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc. [from 17th c.]
3. (uncountable) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice. [from 17th c.]
4. (mathematics) A field of study attempting to exhaustively describe a particular class of constructs. [from 18th c.] Knot theory classifies the mappings of a circle into 3-space.
5. A hypothesis or conjecture. [from 18th c.]
6. (countable, logic) A set of axioms together with all statements derivable from them; or, a set of statements which are deductively closed. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems). The statements may be required to all be bound (i.e., to have no free variables). A theory is consistent if it has a model.
7. (obsolete) Mental conception; reflection, consideration. [16th-18th c.]

Usage notes​

In scientific discourse, the sense “unproven conjecture” is discouraged (with hypothesis or conjecture preferred), due to unintentional ambiguity and intentional equivocation with the sense “well-developed statement or structure”.

Saying "evolution is just a theory" is a straw man fallacy, where the reasoning is a fallacy of relevance: it fails to address the proposition in question by misrepresenting the opposing position.

 

[hutchphd]

here's one pretty awesome for-show-experiment demonstrating and illustrating the concept of evolution:

A truly terrifying piece of work, and a nice video. Makes me want to wear my facemask to bed! Show it often, lest we get too fat and happy.

 

[pinball1970]

On a slight sidestep from the original OP topic, here's one pretty awesome for-show-experiment demonstrating and illustrating the concept of evolution:



Enjoy the ride...

That IS amazing.

 

[gleem]

Even today we are modifying the details of evolution, now we suspect that it may be significantly quicker than previously thought.

https://www.sciencealert.com/evolution-may-be-happening-up-to-four-times-faster-than-we-thought

 

[Filip Larsen]

So Newton's LAW of Gravity would today be called Newton's Theory of Gravity

I seem to recall the convention that historically at least, laws were called "laws" because they are cannot be disproved at such because they are are definitions (e.g. Newton's laws of motion) or are a "fitted description" based on empirical data (e.g. Hooke's law). Right?

If modern work (e.g. in cosmology) happens to call itself a theory I, being just a mortal engineer, am not sure if this is because the distinction has been muddled over the last century or half, or if its just that it has become a more acceptable route to consensus to establish a theory first and then confirm it with empirical data afterwards, rather than doing the old school "fit data at hand to some power law" (or maybe we just ran out of unique power laws to give a name ).

 

[DaveC426913]

So Newton's LAW of Gravity would today be called Newton's Theory of Gravity,

This is not as I understand it.

It is a Law of Gravity because it is empirically derived from observation. Same with Kepler's Laws, etc.
"We see these things happen, given a set of conditions."
It says nothing about how they happen.

Our observations and measurements are not going to change going forward.

just as the more recent, and more accurate theory is called Einstein's Theory of Relativity.

Einstein's GR is a theory because it is an attempt to model how things happen. It could always be replaced with a newer model.

I see Filip has beat me to it.

 

[DaveC426913]

I find myself repeating this one a lot:

Evolution is not a theory; Evolution is a fact. It can be witnessed in any fish shop or dog kennel. We can empirically see that offspring have herited traits from their ancestors.

What you no doubt intend to say is the Theory of Evolution-by-Natural-Selection. That is a theory, because it models how survival pressures tend to drive evolution. That is difficult to show. And it could always be overturned by a new model going forward.

 

[Jupiter60]

There are lots of laws in physics. Laws are less common in other fields of science.

Theories don't upgrade to laws overtime. You will never see an article in a newspaper where a certain scientific theory has officially become a law.

Gravity and evolution are both facts. They can both be directed observed. The difference is that you can directly observe gravity instantaneously. Let go of a ball and it will immediately drop to the ground. To directly observe evolution you need more patience.

Evolution has been observed directly. It is the reason that the ingredients in pesticides always need to be changed because they eventually quit working at killing insects.

 

[Rive]

..."just a theory"...

Somehow, I found all the logical and meaningful explanations for that kind of backward-thought and a bit forced, also: too complex.

So I've came up a solution of my own.
It's just ... everything starts as a theory. And then:
... it sticks.

There was once a discussion about the evolution of science which made an impact on me. It was about the way the new theories overtakes the old. The conclusion was, that surprisingly the old tends to linger around till the old generation is still active. And due this the new generation often politely does not promote the new too forcefully.

 

[Godot_]

The "old generation" are the people deciding what work will be funded...

...so few "angry young scientists" will forcefully oppose them. And those who do tend to not become the most successful ones.

 

[Rive]

...hence the ambiguity of the word 'theory' may come handy when it's about evolution ... of science

 

[Jupiter60]

A common misconception about evolution by those who object to it is what it refers to.

It refers only to how life changes over time, not how life originated, not how the Earth originated, and not how the universe originated.

 

[Godot_]

...which is only somewhat correct - evolution theory after all implies and includes how life evolved from the humble beginnings, and can be used to deduce this. (which can be seen and browsed / explored in the excellent Tree of Life at the onezoom.org website or tolweb.org)

Also, a diehard conservationist (the smarter, rhethorically trained sort) will then maintain that that might be true, but as the world only is 6ky old, this can't explain the plethora of species, so the big G must've created that. *shrug* See above for my reply...

 

[DaveC426913]

...which is only somewhat correct - evolution theory after all implies and includes how life evolved from the humble beginnings,

Sorry, are you referring to Jupiter60's post?

If so, I'm not sure what part you challenge. Any part of this:

"[Darwinian evolution] refers only to how life changes over time, not how life originated, not how the Earth originated, and not how the universe originated."

 

[hutchphd]

Before we descend into a semantic miasma:

"[Darwinian evolution] refers only to how life changes over time, not how life originated, not how the Earth originated, and not how the universe originated."

This meaning depends crucially upon exact definition of "life" vs "non-life" so I declare it unconditionally true. If we really want to try to define "what is life" may I suggest a dedicated thread. I care not to!

 

[DaveC426913]

This meaning depends crucially upon exact definition of "life" vs "non-life"

I am not convinced it does.

1. The fact that there is a grey area between life and non-life doesn't seem to me to affect the definition of Darwinian evolution - which claims to apply only to what is undisputedly life - i.e. the theory errs in favour of caution/modesty. Darwinian evolution does not explicitly say it applies to anything we might consider in the grey area.

2. Even if you wanted to equivocate the near edge of that grey-area, I'd say that does not warrant the use of the "only partly correct" equivocation.

If we really want to try to define "what is life" may I suggest a dedicated thread. I care not to!

It seems to me that's exactly what you're requiring. Nonetheless, I still don't agree it's necessary.

The theory does not make any claims that are called into question by the grey-area. For example, Darwinian evolution does not claim to "drive all life, even from the (albeit poorly-defined) moment of biogenesis".

 

[BillTre]

As @hutchphd said, it a "semantic miasma", not only in how one might define life, but also in what is meant by evolution and Darwinian evolution.

1) I consider the term "Darwinian evolution" a bit of misnomer.
It is usually meant to refer to evolution affecting the frequency of different genes in a breeding population. The "genes" are usually taken as nucleic acid based genes that can generate phenotypes in offspring.
There are a few problems with this:

a) When Darwin can up with natural selection, he had no realistic concept of genetics. That was Mendel, a colleague in time, but overlooked until 40 or 50 years later (well after Darwin died). He described a particle like inheritance. This is Mendelian inheritance. The connection of nucleic acids with genetic "factors" was noticed much later.
What Darwin thought was going on was blending of "factors". These were in some way inherited and lead to traits in the progeny.
Darwin had no great connection to genes. This was a mystery to him and his colleagues, which is why Mendel's findings were such a revelation.
Darwin's insightful vision concerned how natural selection worked to change the frequencies of traits in populations of competing reproducing individuals.

b) Non-genetic traits can be inherited, and therefore selected for or against by natural selection.
There are classic cases in genetics books from when I was an undergraduate (1970's), like the inheritance of cortical patterns of cilia in paramecia. These are propagated through generations, by mechanisms that copy the pre-existing pattern and pass that on to their progeny. By reproduceably generating different inherited patterns of cortical cilia, the entities involved come under the influence of natural selection (favorably or not). (Paramecia with cilia patterns that do not work well for movement or eating will not survive well and will be selected out of the population.)
There are lots of other inheritance mechanisms that don't directly involve genes, often involving "epigenetics".
Some are conceived as inheritance of sets of molecules that could together form an autocatalytic reaction set (makes more of it own components, significant in origin of life considerations). This would be inheritance of different sets of non-genetic molecules passed to progeny as a cell/protocell divides.
Not all evolution involves genes in the Watson and Crick sense.

c) Evolution can proceed without natural selection. Usually, this would refer to changes in gene frequencies in populations over time by mechanisms of random genetic drift (through the luck of which alleles are inherited by which breeding individual. This involves gene frequency changes with impacts on adaptation that are too small to be "visible" to selection mechanisms. this was applied to molecular evolution by Kimura. Michael Lynch has more recently written a lot on this subject.

2) There are literally hundreds of attempts to define life. There is not a lot of agreement on this, so there is no expectation for agreement on when a non-life to life transition might have occurred.

3) By not using a qualifier on the term evolution, @Jupiter60 has left things open to interpretation.
I have my own personal issues with Darwinian evolution (and the NASA life definition that uses that term). I considered using biological evolution instead, that would seem to imply involve defining life.

4) There is a lot of work on what might be called pre-biological chemical evolution of various kinds. Some just involve things like "Where did the complex organic chemicals come from before "life"?". This is covered in geochemistry and systems chemistry. Others involve mechanisms very similar to natural selection working on preps of vesicles containing nucleic acids and how they can evolve over time in the lab. In many ways, the mechanisms in the second group are indistinguishable from natural selection in organisms today.

5) In these confusing subjects, it is probably better in explain, using many words, what you are talking about, rather than using loaded terms, with lots of often forgotten history which can lead to confusion.
You could also ask clarifying questions.

The problem of people misinterpreting the meaning of "theory" in this context (either intentionally or unintentionally, often to make some point) is a similar kind of semantic problem.

 

[MevsEinstein]

Summary: "just a theory"

Why do scientists refer to evolution as a theory which leads to the argument that evolution is "just a theory"? Why don't they use a less confusing word?

It could be that by chance evolution didn't happen but there were just some other animals with similar bones and organs. I mean, it's possible, but highly unlikely.

 

[BillTre]

It could be that by chance evolution didn't happen but there were just some other animals with similar bones and organs. I mean, it's possible, but highly unlikely.

There is more than just the structure (I would also include molecular biology in here) of animals (as well as plants, fungi, and everything else living) supporting the theory of evolution.

There's also fossils. An old explanation for them is that God put them in the ground to test people's faith.
Similarly, God could have created everything a few minutes ago along with our memories, similarly as a test. This approach could explain almost anything.

In general, there are often weird (seemingly unlikely) ways to dismiss evidence that disagrees with some interpretation.
None of it is very convincing.

 

[Laroxe]

I would actually agree that the term is problematic, it's too broad and over inclusive. If we consider evolution as denoting that change occurs over time, then It's pretty clear that evolution is a fact. However, most people use the term in biology to describe an explanatory framework which helps to explain how and why such changes occur. Used in this way, evolution describes a whole range of ideas with each one having different levels of supporting evidence, and work continues in order to refine our understanding.

I think even in physics, there can be similar problems, gravity is clearly a fact but science is more than just a collection of facts, the aim is usually to understand and use this understanding, to predict future outcomes. I suspect that for most people, its the accuracy and utility of these predictions that give the various areas of science their credibility. It has become popular for many people who claim to support science to attack those that challenge the scientific consensus, often when their isn't one.

I'm not really convinced there are large numbers of people who can be described as science deniers, people are avid consumers of the products of science and are often very interested. There are however lots of people who don't like being described as stupid or deniers when they question things, something which used to be considered a hallmark of good science. We also fail to consider the huge social value associated with belonging to large powerful, groups with shared beliefs, this has been a continuing issue in discussions of evolution.

I think that the debates around evolution, provide a really good example of some of the many problems of science in our current culture. Within the loose framework of theories, there are some with the predictive validity of haruspicy, which is fine, (well, not for the animal of course), it encourages debate. It is in fact the lack of debate that leads to these being used to discredit the whole evolutionary framework, it's hard to get good evidence for some idea's, we need to bring back critical appraisal.

I will now get back to proving my own theory that things don't fall down because of gravity, its because the Earth sucks. :)