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Let's get this out of the way first...

In the realm of science, a theory is an idea that is so strongly supported by data and prediction that it might as well be called a fact. But in common conversation among non-scientists, "theory" means almost the opposite. To the non-scientist, calling something a theory means you don't have enough data to confirm it.

I'll be talking about the scientific definition of a theory in this post. And I have one question that I have seen asked many times (unsuccessfully) on the Internet: How often are scientific theories overturned in favor of new and better theories?

I assume Creationists are the ones usually asking the question. And if history is our guide, the comments on this blog will focus on that one area and destroy the value of this blog post. I'm hoping we can ignore evolution and creationism and climate change for one day and just ask the following question: How often does a scientific theory get discarded or replaced with a better one?

I don't think there's a good answer to my question, for lots of reasons.

For starters, I doubt anyone has been keeping a stat on overturned theories. And I don't think it's fair to compare theories from a hundred years ago to theories created today because our ability to collect confirming data today is better than it used to be. I would expect that a theory created recently would be more likely to stand than one created last century.

Still, it has always been true that the stuff we believe today looks way smarter than the dumbass things our grandparents believed. Why wouldn't that be just as true for our future great-grandkids looking back at our primitive beliefs? Some humility is always called for.

Science requires credibility to be useful. And that's a problem. The non-scientist asks "What is your success rate?" and gets no useful answer. Scientists, as it turns out, are terrible at marketing. About 90% of my exposure to science involves media reports that get correlation and causation confused. As a result of that exposure, the more I hear about science, the less credible it feels.

To make matters worse, I have a jaded Dilbert mindset about every industry. Unless science is different from all other human endeavors, 10% of scientists are honest and amazing and doing important science while the other 90% are like Dilbert's worthless co-workers. So when I hear that 98% of scientists are on the same side of an issue, I wonder how many unreliable people you have to add together to get an opinion you can trust.

I don't think I'm alone in my views. I'll bet that if you did a poll you'd find that scientists believe theories are fairly dependable and useful whereas the average non-scientist believes that everything we think we know today eventually gets disproved. Part of the problem is that scientists are looking at utility and non-scientists are looking at "truth" which is a fuzzy and overrated concept.

In every other field, your track record of success determines your credibility. Personally, I have no idea what the track record of science is. All I know are anecdotes about wonderful successes and notable mistakes. I don't even have a general sense of whether scientific theories have usually held up over time or not.

So when scientists say a particular theory is backed by the majority of scientists, how much weight should I put on that? Is that a situation in which I can depend on the scientists to be right 95% of the time or 5%? What's the track record?

Note to the Bearded Taint's Worshippers: Evolution is a scientific fact. Climate change is a scientific fact. When you quote me out of context - and you will - this is the paragraph you want to leave out to justify your confused outrage.


Scott Adams

Co-founder of CalendarTree.com

Author of a book on success. (Makes a good graduation gift, btw)


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Apr 15, 2014
whtllnew: [ If you want it to tell you how we got here/how big the universe is/how will the world end/etc. its track record is pretty lousy (i.e., has gone through a number of changes). ]

That's a lousy way to define lousy. That scientific opinions can change is a STRENGTH, not a weakness. The record would only be "lousy" if opinions were out of sync with the data available when the opinions were held -- i.e., the sun going around the earth makes sense if all the data you have is seeing it rise and set each day.

Others have amply made the point that science does not seek "truth" in the normal sense of the word, so I won't retread there. The point I would like to make is in reference to this:

[ About 90% of my exposure to science involves media reports that get correlation and causation confused. As a result of that exposure, the more I hear about science, the less credible it feels. ]

I think it is more that honest scientists will typically hedge, because they are trained to avoid absolutist statements, which are, of course, ALWAYS wrong. The people who are doing non-science, however, have no such compunctions against certainty, so they come across as more confident in their positions -- and I guess, in a way, they are.

Unfortunately, most people don't understand the difference between "confidence" and "correctness". Why would someone be so confident if they didn't *know* they were right? In reality, there is almost an opposite relationship between the two; the less real data someone has to support their beliefs, the more stridently they will defend them. (Witness sports fans and all other religions.) It is a quirk of psychology that I wish more people understood.
Apr 15, 2014
In my experience, scientific theories are very rarely wholly discarded and replaced. They usually evolve in tiny steps, through the collaborative work of many people. We only hear about big breakthroughs because the small ones would seem trivial and overwhelming to lay folk.

Compare it to the progress of a runner. He starts out running a 10 minute mile, but slowly improves to under 5 minutes. His improvement is not a stairstep of whole minutes, but for convenience he uses those as benchmarks. To an outsider, then whole-minute benchmarks look like discrete improvements, where the last one was thrown out and replaced with the new one. But the runner knows there were a lot more data points in between.
Apr 15, 2014
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Apr 15, 2014

Bumping this from jensfiederer


But this is exactly the kind of 'science' we see in the news:

In 2003, the government in the U.K. launched a widespread effort to encourage companies to gradually reduce sodium levels in processed foods. Now, a new study in the British Medical Journal is showing the impact of this public health initiative.

Researchers analyzed data from more than 31,500 people participating in the Health Survey for England between 2003 to 2011. During the study period, levels of salt intake among the population decreased by about 15 percent. Over the same period, deaths from stroke decreased by 42 percent and deaths from coronary heart disease dropped by 40 percent....

[Wow. OK, sounds good.
We should force food manufacturers to decrease salt in their foods. Let's do it.]

...Rates of smoking and overall cholesterol levels in the population declined over the same period, while produce intake and body mass index both increased. The researchers, from Queen Mary University of London, noted that the single largest factor contributing to the decline in deaths was decreased blood pressure among the population.

[ Wait, so how do you know it was the salt and not the smoking or diet that affected the stroke, disease and blood pressure? Do we force people to remove salt from food or force them to stop smoking or force them to eat veggies? Or was the reduction of salt that caused people to stop smoking or to eat right? ]

Are these scientists worth listening to, is their track record of success any good? Where is the scientific communities version of the Better Business Bureau or where is the Consumer Reports of science?

Stop using bad science to force a behavior change. It makes me not trust you.

Apr 15, 2014
Scientist here.

Two points need to be made. First, most theories are wrong. Really. For any bit of unexplained phenomena there will be ten wrong explanations for every right one. There is a free scientific paper hosting site called the arXiv that has nearly a million papers, and most of the theoretical ones are "wrong" to some extent. Some fields are better than others, and your mileage may vary, but in one field it has gotten so bad that someone made the snarXiv of randomly generated buzzwords and you can play the arXiv vs snarXiv game to try and guess the real paper.

This brings us to the second point. In real science, wrong theories are still helpful. We still learn and move forward by testing predictions and proving them wrong. A wrong theory isn't a failure, its progress. (Of course, a right theory is better, but no one gets lucky all the time)

Apr 15, 2014
@EdconDilbert "adding CO2 to the atmosphere will continue to increase IR absorption and re-emission, and that will continue to warm the earth."

Just about nobody disputes that. However, if you dig into the reports, you will see that a doubling of CO2 will cause roughly 1.5 degrees Celsius of warming on it's own. In order to get the catastrophe, you have to have all kinds of positive feedback effects in water vapor concentrations, etc. that amplify the CO2 driven problem.

That is where the controversy is. Some people believe in positive feedback effects and some people don't. The pro AGW crowd knows that this is where the disagreement is, but they (and the media) continue to frame the debate as "deniers don't believe CO2 raises temperature", in order to discredit the skeptics. That is why they keep pointing to statements like "95% of scientists believe mankind is a/the primary cause of global warming".

What you won't find is statements like "95% of scientist believing that CO2 causes warming, and warming causes other effects that amplify the warming until we reach catastrophic levels", because there is nothing near consensus on that.

That being said, I believe you can have an honest belief in the positive feedback effect. You can also have an honest belief that the feedbacks are more likely to be negative - i.e. that other parts of the earth's systems are likely to offset CO2 driven warming.

(The negative feedback argument has two very strong attributes in its favor. First, if the earth was driven by positive feedback systems, it would be unstable, and past periods of high temperature would have basically turned us into Venus. Secondly, the models that rely on positive feedback effects have consistently overestimated future warming).

But, the bigger point is that the AGW crowd and the media want to frame the debate as "CO2 does/does not cause warming", because that makes their case look unassailable, whereas the real debate is "feedback cycles are positive vs. negative", which is terrain upon which the evidence is much less favorable to their cause.
Apr 15, 2014

[Science gets too much scrutiny, probably because scientists have admitted they were wrong so many times. What about… say… humanities. We live in a world where 98% of English literature experts will agree that a given classic is a great, entertaining work of fiction (and you basically have to agree with this to become an "English literature expert") and people buy into this, even though all of us who read said work find it to be a boring piece of crap. I think you should write a post about that. Why do we trust these people to tell us what is "good" and what isn't?]

Hands up anyone who actually trusts english teachers/professors to tell them what books they should read for their own enjoyment.

Apr 15, 2014
never attribute to malice that which can be plausibly explained by ignorance or laziness...

people say theory when they should say hypothesis b/c the later has four syllables versus the former's two. I used to get criticized for using "unnecessarily big" words - the fact that the bigger one was correct and the shorter one not was irrelevant (or more frequently the more verbose version was more precise and/or accurate).

I suppose one could argue that a plausible hypothesis IS a theory given an acceptably large "p" {sigh...}
Apr 15, 2014
I can't actually think of a scientific theory (established in the way you mean in this post) that's been discarded. The typical evolution is that existing theories are extended by new theories when we learn to work in new areas. Newtonian mechanics isn't wrong and hasn't been discarded. It's been extended into the world of the very small by quantum mechanics and into the world of the very fast by relativity.

Similarly, modern evolution theories extends Darwin's work, especially in mechanisms of selection and less intuitive behaviors that are selected. But new theories (established in the way you mean in this post) aren't going to replace evolution by variation and natural selection.

And future work on global warming will improve our data, add additional (smaller and smaller) effects, and extend our understanding from global averages to include geographical and seasonal variations. But adding CO2 to the atmosphere will continue to increase IR absorption and re-emission, and that will continue to warm the earth.
Apr 15, 2014
If anyone has kept track of this stat it would have been Feyeraband


But I have to concur with your thought, scientists would find most scientific theories reliable while people would seek truth of the brand they seek with predictable results. Speaking of predictable results scientists would come up with Moore's Law versus this Byte Magazine cover: https://archive.org/stream/byte-magazine-1981-04/1981_04_BYTE_06-04_Future_Computers#page/n0/mode/2up

Apr 15, 2014
@MTBob... Spoken like an engineer who pays too much in taxes!

...and for the blog....
This seems like the perfect time to throw this out: remember a while back when the article came out that there is evidence we may just all be holograms? (Referenced in this blog?) I wonder if perhaps God is a programmer. It just seems too coincidental. Creation, evolution, either way, it is code reuse. I mean, if you write a great bit of code, you reuse it and tweak it, and wouldn't you agree that one of the basic foundations of all life is that DNA is present?

I would say that's a Theory we can all get behind. ;-)

Keep up the good writing; love the Thought Experiments on a nearly daily basis!
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Apr 15, 2014
Scott: "How often does a scientific theory get discarded or replaced with a better one?"
What's your definiton of being discarded and replaced? Or can you give an example?
I mean, theories get modified all the time in order to better fit the observed facts.
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Apr 15, 2014
When we hear statements like "95% of scientists agree anthropogenic climate change is real", I don't think that's supposed to be an "argument from authority". If you're concerned about the topic - as they are - you have to say *something*, even if you expect the usual suspects to attack it.

You don't have to take their word for it, you can examine the evidence behind the consensus and draw your own conclusions. However, that requires a level of intellectual honesty, the willingness to examine *all* the evidence, not just the bits that support your biases.
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Apr 15, 2014
DISCLAIMER: Absolutely no evidence for anything that follows.

A couple big differences between now and a few hundred years ago that make 'comparison' difficult is that while a) scientific fields of study have become a lot more specialised requiring much more background study to even get started working on anything new, simultaneously b) much more people have a basic level of exposure to the same stuff. "Back in the day" scientists were often polymaths and entire fields of study could be comprehended by just reading one book and the only people reading those books and therefore giving a damn about the field were the educated elite.

By way of example, Newtonian Gravity and Evolution are fundamentally quite easy to understand, there are nuances of course that get tricky, but with a basic level of scientific literacy most people can understand the concept. I have an engineering degree and quite substantial scientific reading behind me but I can't understand more than the absolute simplest explanation of the Higgs Boson field or Big Bang Inflation.

This is why scientific consensus becomes important. Yes we know that it's not infallible and yes it's not hard to find examples of where "we used to think..." but that doesn't in itself prove the consensus wrong. What they should say is, "the people who understand this at all mostly think..." and "BTW YOU probably don't understand this. Sorry."
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Apr 15, 2014
I think science's "track record of success" is not how many theories stay unchanged. It's how successful the existing theories are in understanding Nature.
I would say that putting a man on the moon (and bringing him back!) using nothing but scientific knowledge is a pretty good track record (not to mention the near-infinite number of other useful, or at least impressive, accomplishments).
Revisions to scientific theories are more like refinements, and as time goes by, they become more and more like refinements and less like "overturns". Our accuracy keeps getting better. The new theory of today may be radically different than that which it replaces, but its implications are usually in the 10th decimal place, and about something at the edge of the universe. Newton's theories can still be used to launch satellites into orbit.
Apr 15, 2014
Your mistake is to mis-identify where scientists' credibility comes from - they get the greatest kudos from upturning the current theory.

I was lucky enough to visit the Large Hadron Collider at CERN just before it started operating. A Chinese scientist was showing us around, saying how wonderful it would be after 20-odd years of effort to find the Higgs boson.

As non-scientists, one of us asked the obvious question: "And what if you don't find it?"
The scientist excitedly replied with a huge smile "Ah, that would be MUCH more interesting!"

Apr 15, 2014
If it turns out that there's a flaw regarding the discovery of atoms, then that might mean that we don't exist. On the other hand, we must exist since we have no place else to be.

If you have any questions regarding this memo, please bring them up in the latter pre-meeting meeting this Thursday.


Apr 15, 2014
Maybe make that "200 years". Einstein's theories are 100 years old and so far the more they get tested, the more they hold together... Just sayin'.
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Apr 15, 2014
Putting together the words *taint* and *beard* always triggers a sophomoric snicker.....
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Apr 14, 2014
Scott, you are a social media genius! You’re the best!

After following your writing for a long time, I still wonder when you’re just messing with us. You are way too intelligent for us to really believe your opinion that evolution and global warming are facts.

What animals that are still evolving (not adapting)?
What will the climate look like in 500 years based on facts?

-Bearded Man
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