Why not? Another post on Evolution

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We're on a roll here, so I figured I'd post my pet peeve about Anti-Evolutionism. I know I do so at my peril as I'm hitting two hot buttons at the same time: Evolution, and Language Usage, but here goes...

I'm really tired of hearing Anti-Evolutionists say things like "Even scientists think that Evolution is just a Theory, not a Law." Well, if you omit the "just", then that is entirely accurate. However, scientists mean something very different by "theory" and "law" than the common usage.

In everyday language, we use "theory" to mean an as yet unproven possibility. And in the Anti-Evolution slogan, the "just" implies that usage and contrasts it with "law" with the implication that laws are proven. Thus, the implication is that even scientists don't fully trust evolution else they would have called it the Law of Evolution.

This is to completely misunderstand how scientists use the words "law" and "theory". In scientific contexts, a law is an elegant statement of a basic regular feature of the universe. It is elegant in that it can be stated in a very definitive manner through an equation or a couple of unambiguous sentences. As such, it is narrow in scope and concrete in meaning. Laws are simple.

Theories, on the other hand, are complex. They describe whole systems. They are much broader in scope than laws. As such, they cannot be written as concisely, nor as concretely.

The primary difference between a law and a theory is scope, not reliability.

The law of gravity, Newton's Laws of Motion, Kepler's Laws of Planetary Motion, etc. are all expressible as concise equations or single sentences. The Theory of Relativity, the Theory of Quantum Mechanics, the Molecular Orbital Theory, Atomic Theory, etc. encompass to much to be expressed so simply. But scientists don't think that the Laws are better than the theories. In fact, scientists think that the Theories of Relativity and Quantum Mechanics trump Newton's Laws.

So just because Evolution is classified as a theory does not imply that it has yet to pass some critical test in order to become a law. It is simply to say that Evolution is too broad in scope to be classified as a law.

(Now one could point out that both scientific theories and scientific laws can be in error, and you would be right. But that is a whole nother discussion that has little to do with my pet peeve.)

(I should also point out, as has been noted in Abednego's "Evolution and the Pope", that evolution as a scientific theory is compatible with Christianity (though neither implies the other). Naturalistic evolution as a philosophical worldview, on the other hand, is not.)

18 Comments

I think there's some sense that more complex theories are harder to confirm and thus less likely to be true. Simpler ones, by Occam's Razor, are almost universally agreed to have better support. Many theories do have an extremely high support, but I don't think the difference between simpler laws and more complex theories is merely over the simplicity or complexity. I do think there's an epistemic difference. That doesn't justify treating a theory as a mere hypothesis, which is what the people you're complaining about do, but I think it does justify distinguishing between theories and laws in more ways than just degree of complexity. No one ever put special relativity on the same level as Newton's laws of motion. As it turns out, they're all false, but the laws of motion had a higher degree of certainty until they were seen to be false than special relativity did before it was seen to be false.

Hi Wink,
Well this is my field so how can I resist? Jeremy is right - the difference is not one of simplicity and complexity. It's a difference in the amount of direct evidence. There are three common terms used: model, theory, law. A model contains some findings (evidence) with a lot of gaps - you could say that a model doesn't refute observed phenomena, but that it is speculating or hypothesising to fill the gaps. A model is a work plan really - here's some of the pieces, this is how we think it would all fit - and we need more direct evidence to substantiate it. Margulis symbiotic hypothesis, which proposes the origin of mitochondria is a good example of a model.
A theory contains a lot more direct evidence. However it still contains gaps - either because the experimental data has not been obtained, or because it cannot be obtained. In the case of evolution there is data that simply cannot be obtained - we cannot recreate species which are now extinct for example. The fossil record is incomplete as another example.
A law is based on direct evidence. There are no gaps as far as the law is concerned. However the defining of a law does not preclude that other laws may work in conjunction with that law. A real law should not be incorrect. An incorrect law is one that has passed peer review without adequate critque.
A law may be simple of complex - or based on a complexity of data but expressed in it's most simple terms.
A model may be simple or complex, likewise a theory. It is a difference in the amount of direct evidence contained within the position. Sometimes model and theory can be confused a little. Example - some scientists refer to the prion hypothesis, others refer to it as a theory as we do not know how proteins appear to self-replicate, but there is evidence that these aberrant proteins do. A law is not confused.

Hi Jeremy,
Just a quick observation. Relativity, general and special, are theories as I understand it, rather than laws. It could be debatable I guess, but Einsten presented them as theories. I'm aware that some physicists have attempted to refute special relativity, but am not aware of anyone conclusively proving it false and presenting a substitute. Are there any journal articles you know of? (I don't read all the physics stuff - too busy reading blogs!)

A philosopher of physics from Rutgers (which goes between #3 and #1 in the philosophy rankings most of the time, so this is a specialist at a top institution) told me that special relativity has been decisively refuted. I don't know the details. It might have had to do with assuming spacetime to be Euclidean, which we now know is false. If that's the issue, then it would simply be a matter of replacing the Euclidean axiom with one of the other two systems, but we don't know which one of the other two is correct.

Hmmm, I guess I should have done more fact checking before posting. I had always understood that a model was of lower episetemic certainty than either a theory or a law, but that there was no similar step separating theory and law. This was bolstered by the fact that there are theories are are utterly complete and contain no gaps, yet are called theories and not laws. Take Molecular Orbital Theory for example. There are no data gaps in this theory, and it has no exceptions. True, it is only accurate to a first or second approximation of reality, but the same could be said for Newton's Laws or Kepler's Laws. So why is MO Theory not called a law?

We didn't know Newton's laws were wrong about very small particles until long after they were called laws. Is the same true of MOT?

Hi Wink,
I've given you what we work with, and explained how there is some overlap between model and theory. Molecular orbital theory? There probably are pieces of data that cannot be directly determined. To be honest I'm not going to look it all up. Theories can appear to be complete in terms of direct evidence but are not. There is a difference between extrapolating data and having direct evidence. When you say "there are no gaps in this theory" I think you miss it - the theory will not appear to have gaps - it will all hang together. i.e.e evolution just as an example. But the direct evidence for some parts of the theory is not available. It's an important distinction. I'm not actually arguing pro or con evolution, just looking at the usage of the different terms.
Jeremy - yes, you are onto something there. Also Newton had an easier time of it calling something a law. Which does bring us to the limitations of the human mind in a way. Appreciate your comments on special relativity. I think I'll dig around on that.

ooops - to not confuse things - with MOT I should have said there are possibly pieces of direct evidence missing.

I think we're trying to press these terms somewhat beyond how they're really used in science. I think particular theories/laws get the name theory or law associated with them in the beginning, and there's no "official" way of determining whether something should be called a theory or a law; it's just a matter of convention. There's no court that weighs the evidence and decides between one or the other. I do think, however, that Wink is somewhat on the right track, in that a law is often a more concise statement than a theory. But in all my science classes I've never heard anyone make this distinction before. We just have particular names for things -- law, theory, model, etc., and we just call things whatever everyone else calls them.

Here are some specific examples:
1) Einstein's "theory" of Special Relativity. This states simply that the speed of light is constant with respect to any observer, regardless of the observer's velocity. The statement is simple enough that you might call it a law, as it's verified on a regular basis now. From that, one can use some basic trigonometry and show a lot of other things. But the theory itself is quite simple, even compared to other "laws". Why not call it a law? There's direct evidence for it, too. But it's called a theory simply by convention. And for Catez and Jeremy: There is a huge amount of direct evidence for special relativity, yet it is still considered a theory.
2) Newton's Laws and Boyle's Law: These are expressed by simple equations, but are really (we now know) oversimplified. That is, they are a good approximation under some (or many) conditions, but they don't apply universally. For example, there are corrections to Newton's laws due to the effects of Special Relativity under some circumstances, and due to quantum mechanics under others. They are, however, concise statements, as Wink points out.
3) Quantum Mechanics: I hear scientists talk about the laws of quantum mechanics. Others talk about the theory of quantum mechanics. QM is sort of tricky, because one can use it to make predictions about the outcome of experiments which provide a significant amount of evidence that it's right, but it's hard to test the theory itself at the most basic level. There are also a number of people who try to draw philosophical conclusions from QM, which I find even more troubling. Nevertheless, I think the fact that there's some disagreement about whether it's a "law" or a "theory" shows that things aren't so simple.

I think part of the problem is that scientists themselves don't really think about the difference between a law and a theory, so probably people have different definitions of the two.

My own opinion based on usage is that a "law" tends to be used to describe something which applies without exception under certain known conditions, and has been fairly well tested, while a theory is more often used to describe something studied recently which is somewhat less well tested. Laws, for example, can still be laws if they are oversimplifications and thus are wrong in some situations (like the two I mentioned above). And Special Relativity is a case where the amount of attestation doesn't seem to affect the designation of theory vs. law. So again, things aren't so simple.

So I think it would be more useful to make several sorts of distinctions that scientists usually don't make, as it could help focus debate, etc. First, one could distinguish between different sorts of theory/law (considering theories and laws together) based on the amount of evidence. Suppose we decide to call them all theories. We could have "strong theories" and "weak theories". And, I think more importantly, we could distinguish between theories based on the *kind* of evidence. Someone recently pointed out that much of modern science is done with the hypothetico-deductive method: You develop a hypothesis, then predict what should be true if your hypothesis is correct, then test those predictions. If you do a good job at making predictions, odds are you'll easily be able to find out if your theory/hypothesis is wrong because experiments will show your predictions to be wrong. After you do enough experiments in this way, you tend to get some confidence your theory is right, and with good reason: Your theory is correctly predicting what will happen. This is what goes on with theories like special relativity, quantum mechanics, etc. etc. For example, special relativity says that the speed of light is constant regardless of the observer's motion, so people try and measure the speed of light in different directions, and find that it appears constant.

But the other sort of approach is the inductive method, where one takes evidence that is available and tries to come up with an explanation for such evidence. This often applies more to history: For example, Big Bang Theory works (at least in part) this way: There are some facts about the universe, and one explains them by suggesting that the universe began with a bang 15 billion years ago. Evolution (at least, common origins) also works this way. Now, people will also try to test these by predicting other things we should see in the present (the cosmic microwave background is one such prediction from big bang theory), so really in practice this ends up being somewhat of a blend with the first method. But still, it seems like a fairly useful distinction. It's much more difficult to gain confidence that a theory correctly describes past events than it is to gain confidence that a theory correctly describes future events, simply because if we have a theory for future events, we can directly test its predictions. With a theory about past events, we're limited to evidence that is more peripheral.

Interesting post wink. I have never heard a creationist say that evolution is a theory, not a law. I think this is because, in lawman's terms the concept of scientific law is not understood (Just as the mistake what a 'theory' is in science).

What I have heard most often is that evolution is a theory, not a fact. Which is one sense correct. In science a fact is merely an observation such as the intensity of light coming from the sun. As such, evolution (Common descent, goo to you sort of evolution) does not fit into this category (And cannot because it is historical) Once again however, as you have said, the layman does not use the term 'theory' correctly. It doesn't help the clarity when many evolutionists say that evolution is a 'fact'.

FYI, I think calling evolution a theory gives it way too much credit. It is way too plastic to give real predictions. This is why Karl Popper called it a meta theory, a useful concept for bringing together many other theories.

A fact is not an observation. An observation is a perception of something that's factual. A fact is more like a truth, and an observation is more like how we discover the truth. Evolution is indeed a fact if the theory is correct. The problem with saying it's a theory, not a fact is that it puts these two things as opposites, when they're not. If the theory of general relativity is correct, then the equations of the theory are facts. Whether something is a fact depends on how the world is. Whether something is a theory depends on facts about our understanding, perception, and confirmation of further facts.

An analogous conversation might go like this. A theist claims that God exists. An atheist says that's nonsense. There's no evidence for it, and any proposed evidence can be taken in a different way. The theist says personal experience and the inner light of God's revelation count as evidence too, but the atheist refuses to accept that because only certain people have access to it. Atheists want their own inner light if they're going to accept that as a convincing argument for theism. As the discussion continues, the theist gets more insistent that God's existence is a fact. God really does exist. The atheist counters, "theism is a theory, not a fact". To the theist, that just sounds silly. It's a theory in the sense that it's a view that some people hold, that those people think has been confirmed over and over again to them even if others can't see it. Maybe they even think those others are ignoring the best evidence. What's stupid about the statement is that none of that would mean that it's not a fact. However unconfirmed the atheist thinks theism is, however irrational the theist's belief might be, that doesn't give the atheist the right to say it's not a fact with 100% certainty unless the atheist has 100% certainty, which doesn't seem to be the sort of thing you can have about theism. To the theist, this statement sounds so odd because it says that something is not a fact when it should be saying something about our understanding, evaluation, and level of certainty about whether it's a fact.

When you bring it back to evolution, the statment amounts to this. It's like saying that evolution is not fully confirmed, and therefore it's not true. That's about as bad a non sequitur as you can get. No matter how bad your support for a thesis is, that doesn't mean that thesis is false. What you need to establish it's falsity would be arguments against it. No matter what you might mean by saying something is a theory, it can't mean that there are arguments against it. The term at best has to do with the lack of arguments for it, and thus it doesn't make sense to contrast something's being a theory with being a fact, even on the most charitable interpretation of what people mean when they say this.

Completely not in the flow of the discussion but spurred by someone asking about a substitute for Einstein's relativity. Someone recently linked to this http://www.peterlynds.net.nz/ on my site and it seems (so far) pretty interesting.

Evolution (as in molecules to man) is not supportable as a 'Theory'. (as the term is used scientifically)
No transitional form has ever been found. (a couple of fakes have been put forward in the past)
For 'molecules to man' to work there has to be information added to the DNA. No evidence for this has ever been found.
Evolution (molecules to man) plays no part in true science.

Jeremy, the problem with defining in science that 'fact' = 'truth' is that science does not get truth. Science is always tentative, giving the best explanation it can at the time. Hence according to your definitions, there is no scientific value in calling anything a fact because that is saying more than science is able to say.

I have no problem with that conclusion, Alan. There are some real problems with taking the results of science as guaranteed and certain truth, given that most of the things we were most sure of 100 years ago have turned out to be only approximations. We're getting closer to the truth, and thus to real facts, but that doesn't mean the results of science are always going to be facts. Some of them will be. We just don't always have access to which ones are and which aren't.

Never mind, I'll leave you to play as there is nothing serious going on here.

Jeremy, Fair enough. But I think it is dangerous or unclear to say that we are getting closer to the truth. It may be the case in many instances, but science cannot tell us that. This is because as knowledge grows, so does our understanding of the possible explanations and causes.

Let me explain. In empirical testing we test a hypothesis by controlling the variables that can affect the outcome.

For instance, in a year 7 science class I taught many years ago we tested the effects of viscosity on the rolling speeds of the containers the viscous liquids were contained in. To control the variables, the same containers were used for each liquid, the same amount of each liquid was put in each container and the same slope was used to test the speed.

However, as our knowledge has increased, so has our knowledge of the different variables that would need to be controlled. If our knowledge of those variables grows faster than our ability to control those variables, we may be 'closer' to the truth in one sense, but further away in another.

It is also the case than a new variable or explanation can completely replace an existing explanation. When this happens, although you may have said that the previous explanation was 'closer' to the truth that the explanation before that (The previous previous explanation), it was in fact not.

Essentially science uses induction, which is a logical fallacy. It attempts to mitigate this by controlling the possible causative agents (variables) in experimentation, but this relies on having an exhaustive knowledge of those possible causative agents, which is impossible.

By a closer approximation, I mean that the results of a theory will give answers that are much closer to the right ones. I do not mean that metaphysical views will always be closer. I'm talking about things like Newton's laws, which we now know to be false. They're false, but they're so close to being true that when we use them we get exactly the answers we want at the level of precision we want when we're dealing with the macroscopic level.

Induction is a problem in philosophy of science, but it's a problem given certain views in epistemology, ones I don't share. I hold to the dominant epistemological view in philosophy today, which holds that you don't need to have access to what makes your belief reliable for it to be knowledge. You don't have to know that you know for it to be knowledge nonetheless. If you use a reliable method to get true beliefs, and they're caused by the thing they're about, then it's knowledge. Science can do that. Induction can lead to true beliefs in a very reliable way, beliefs caused by the very thing they're about. You can't prove that the method is reliable, but if it is then it counts as knowledge in the same way that beliefs about the external world from our senses count as knowledge as long as our senses really are reliable and lead to true beliefs caused by the external world. Using induction as an argument to say that you have demonstrated the truth of your conclusions without doubt would be fallacious, but no one thinks inductive arguments do that. All they do is make it more reasonable to believe something than something without as much confirmation.

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