Hacker News Reader

Comment by aazaa | Hacker News Reader

Sort of meta, but I always shudder when someone says that science has "proven" something.

What sets science apart from most other methods of seeking answers is its focus on disproof. Your goal as a scientist is to devise experiments that can disprove a claim about the natural world.

This misconception rears its head most prominently in discussions at the intersection between science and public policy. Climate change. How to handle a pandemic. Evolution. Abortion. But I've even talked to scientists themselves who from time to time get confused about what science can and can't do.

The problem with believing that science proves things is that it blinds its adherents to new evidence paving the way to better explanations. It also leads to the absurd conclusion that a scientific question can ever really be "settled."

View on HN

Proof never proves it only implies. People are just bad at weighing how much proof there is and how heavily it implies something. Nuance is inconvenient in policy discussion and public discourse.

Science also doesn't seek disproof. It uses both example and counter example to confirm or deny or increase how much one confirms or denies.

Not to be rude, but given current daily attacks on science and the scientific method, I can't let this stand - I think your meta intuition represents a fundamental misunderstanding of how science works.

It is simply wrong to think that scientific questions can never be definitively settled. Clearly there are some hypotheses that have been difficult (and may be impossible) to prove, for example, Darwin's idea that natural selection is the basis of evolution. There's ample correlative evidence in support of natural selection, but little of the causal data necessary for "proof" (until perhaps recently). In the case of evolution the experiments required to prove that natural selection could lead to systematic genetic change were technically challenging for a variety of reasons.

In the case of climate change, the problem again is that the evidence is correlative and not causal. Demonstrating a causal link between human behavior or CO2 levels and climate change (the gold standard for "proof") is technically challenging, so we are forced to rely on correlations, which is the next best thing. But, you are right, it is not "proof".

Establishing causality can be difficult but not impossible - the standard is "necessary and sufficient". You must show necessity: CO2 increase (for example) is necessary for global warming; if CO2 remains constant, no matter what else happens to the system global temperatures remain constant. And you must also demonstrate sufficiency: temperatures will increase if you increase CO2 while holding everything else constant. Those are experiments that can't be done. As a result, we are forced to rely on correlation - the historical correlation between CO2 and temperature change is compelling evidence that CO2 increases cause global warming, but it is not proof. It then becomes a statistical argument, giving room for some to argue the question remains "unsettled".

My point is that there are plenty of examples in science where things have been proven -- DNA carries genetic information, DNA (usually) has a double stranded helical structure, V=IR, F=Ma, etc. And there are things that are highly likely, but not "proven", e.g., human activity causes of climate change.

While some of the issues you bring are remain unproven, what's really absurd is to think that no scientific questions can be settled.

I think this goes against the basis of the scientific method. There is a reason why they say everything is a hypothesis and nothing is every proven. Anyone can propose an alternative model explaining something you call proven; you calling something proven does not inherently make that explanation correct.

This is not mutually exclusive with being against the attacks on science. Just because we shouldn't treat things as proven doesn't mean we can't come to a general consensus on a topic and act as if it was true. Climate change is real. Evolution is real. Don't inject yourself with bleach. Having a small number of quacks say 'its just a hypothesis and actually god is responsible for climate change and evolution' without any evidence doesn't change the general consensus and doesn't mean we have stop everything until we prove the negative.

Ultimate I think most of us agree in principle. Most of what we're discussing here is minor semantic differences in vocabulary.

Everything in science remains open to be disproved; it wouldn't be science otherwise. That's one way science is different from pure math. Or from religion for that matter.

That said, it is indeed annoying when people who don't understand science interpret "open for disproof" to mean "it's easy to disprove." Quantum mechanics and the second law of thermodynamics could in principle be disproven, but the evidentiary burden would be extremely high. (Insert obligatory Carl Sagan quote here.)

No. What is the basis for these claims?

They're both wrong.

It's not true that CO2 increase is necessary for global warming. If the sun got a lot hotter, global temperatures would rise. If non-CO2 GHGs increased, global temperatures would rise. If the overall albedo of the planet changes, global temperatures can rise. There are literally thousands of things that could cause the temperature to rise.

It's also not true that CO2 increase, holding everything else constant, would lead to long term or even medium term warning. We have no idea what the ecosystem will do for any given change in CO2 levels, since there are countless species both who are net producers and net consumers of atmospheric CO2, all of whom have exponential growth and feedback loops.

Even still, even since both of those claims are wrong, CO2 increase may still cause global warming.

Furthermore, the things you claim are proven, are not proven, they are true by definition. All molecules carry information, and the fact that DNA carries genetic information is a direct consequence of the fact that it is DNA. V=IR by definition. F=ma by definition. There's no such thing as a "force" or "mass" or "acceleration" entity per se, these are metrics that are by definition equal in a given physical framework.

There is no way to 'technically' prove anything in science, and the reasons are simple:

(1) The past is gone - you can't access it

(2) You can't see the future

(3) Your knowledge of the present is extremely limited and inaccurate

These are the limitations of the real world, and science does its best to provide utility within that. It only focuses on making future predictions using the observed past as evidence, because you only can do that. You can't check your model in the present, because you can't instantaneously observe anywhere you aren't already observing. Checking your model on the past relies on what you think happened, i.e. what allegedly happened, but there is absolutely no way to truly know.

You can't even really prove anything 'novel' in mathematics, which is the only place where you can actually prove anything, but even there all proofs are effectively just framing something that was already implied axiomatically in a way that allows our limited human minds to see the relevant/useful patterns that aren't immediately obvious to us.

My point is, acting as though you can truly prove anything in science,

> what's really absurd is to think that no scientific questions can be settled

is not only wrong, but in my opinion is a distraction from what science is actually for. It's not about settling questions. Science is never settled, and that's part of what's beautiful about it. It's about reducing our own ignorance and proving our past selves wrong, discovering patterns and models that equip us with the knowledge to build a better world for ourselves and the rest of humanity.

Why lie about being a great soccer player when you're already great at basketball? Let's focus on the beauty of science as a great journey of growth and exploration that accelerates the progress of humanity, instead of trying to make it do something that isn't possible in the real world.

> No. What is the basis for these claims?

"Science", as it is represented in the media, and in turn repeated and enforced (not unlike religion, interestingly) on social media and in social circles.

As opposed, of course, to actual science.

"Perception is reality." - Lee Atwater, Republican political strategist.

https://www.cbs46.com/news/perception-is-reality/article_835...

https://en.wikipedia.org/wiki/Lee_Atwater

"Sauron, enemy of the free peoples of Middle-Earth, was defeated. The Ring passed to Isildur, who had this one chance to destroy evil forever, but the hearts of men are easily corrupted. And the ring of power has a will of its own. It betrayed Isildur, to his death."

"And some things that should not have been forgotten were lost. History became legend. Legend became myth. And for two and a half thousand years, the ring passed out of all knowledge."

https://www.edgestudio.com/node/86110

Threads like this one, and many others like it, well demonstrate the precarious situation we are in at this level. Imagine the state of affairs around the average dinner table. Although, it's not too infrequent to hear the common man admit (which is preceded by realization) that they don't know something. As one moves up the modern day general intelligence curve, this capability seems to diminish. What the exact cause of this is a bit of a mystery (24 hour cable propaganda and the complex dynamics of social media is my best guess) - hopefully someone has noticed it and is doing some research, although I've yet to hear it mentioned anywhere. Rather, it seems we are all content to attribute any misunderstanding that exists in modern society to Fox News, Russia, QAnon, or the alt-right. I'm a bit concerned that this approach may not be the wisest, but I imagine we will find out who's right soon enough.

> I think your meta intuition represents a fundamental misunderstanding of how science works.

It sounds to me like the grandparent is 100% correct.

> It is simply wrong to think that scientific questions can never be definitively settled.

They made no such claim, speaking of intuition.

> Clearly there are some hypotheses that have been difficult (and may be impossible) to prove, for example, Darwin's idea that natural selection is the basis of evolution

I've seen very little evidence in online discussions (Reddit for example) among armchair scientists that the theory of evolution is anything short of cold, hard, scientific fact.

> In the case of climate change, the problem again is that the evidence is correlative and not causal. Demonstrating a causal link between human behavior or CO2 levels and climate change (the gold standard for "proof") is technically challenging, so we are forced to rely on correlations, which is the next best thing. But, you are right, it is not "proof".

Is this (it is not proven) the message they're sending when they say things like "The science is in", just as one example?

> Establishing causality can be difficult but not impossible - the standard is "necessary and sufficient". You must show necessity: CO2 increase (for example) is necessary for global warming; if CO2 remains constant, no matter what else happens to the system global temperatures remain constant. And you must also demonstrate sufficiency: temperatures will increase if you increase CO2 while holding everything else constant. Those are experiments that can't be done. As a result, we are forced to rely on correlation - the historical correlation between CO2 and temperature change is compelling evidence that CO2 increases cause global warming, but it is not proof. It then becomes a statistical argument, giving room for some to argue the question remains "unsettled".

This is not the message I've heard, at all, from any mainstream news source, and it's certainly not the understanding of 95% of "right minded" people I've ever encountered.

> While some of the issues you bring are remain unproven, what's really absurd is to think that no scientific questions can be settled.

What's even more absurd, to me, is how you managed to find a way to interpret his text in that manner. And you're obviously (based on what you've written here), a genuinely intelligent person. Now, imagine how the average person consumes and processes the endless stream of almost pure propaganda, from both "sides" on this topic and many others.

The unnecessarily dishonest manner in which the government and media have chosen to represent (frame) reality to the general public has left an absolutely massive number of easily exploitable attack vectors for "conspiracy theorists" to exploit. And if you are of the opinion that all conspiracy theorists are idiots so you have nothing to worry about, consider the possibility that this too has been similarly misrepresented to you.

If a society chooses to largely abandon things like logic and epistemology in the education of its citizens, thinking propaganda is a suitable replacement, don't be surprised when things don't work out in your favor. If we can barely manage such things here, why should we expect Joe and Jane six-pack to somehow pull it off?

See no evil, hear no evil, speak no evil.

Amen.

It kind of floors me that we're taught science the way it is. Much simpler: Karl Popper's conjecture and refutation. So I tell people that science mandates "I believe something, so I should try to prove it wrong." I think understanding that is significantly more beneficial than repeating the arbitrary n- steps of a scientific method. It's two steps. Keep it simple.

One thing that rubs me the wrong way about this "no proof ever, only disproof" attitude is that it advantages the new hypotheses too much.

Any hypothesis that I invent at this very moment, is from this perspective in the best position a hypothesis can ever be. There is no disproof. There is even no coherent argument against it, because I literally just made it up this second, so no one had enough time to think about it and notice even the obvious flaws. This is the best moment for a hypothesis... and it can only get worse.

I understand that there is always a chance that the new hypothesis could be correct. Whether for good reasons, or even completely accidentally. (Thousand monkeys with typewriters could come up with the correct Theory of Everything.) Yes, it is possible. But...

Imagine that there are two competing hypotheses, let's call them H1 and H2.

Hypothesis H1 was, hundred years ago, just one of many competing options. But when experiment after experiment was done, the competing hypotheses were disproved, and only this one remained. For the following few decades, new experiments were designed specifically with the goal of finding a flaw in H1, but the experimental results were always as H1 has predicted them.

Hypothesis H2 is something I just made up at this very moment. There was not enough time for anyone to even consider it.

A strawman zealot of simplified Popperism could argue that a true scientist should see H1 and H2 as perfectly equal. Neither was disproved yet; and that is all that a true scientist is allowed to say. Maybe later, if one of them is disproved in a proper scientific experiment, the scientist is allowed to praise the remaining one as the only one that wasn't disproved yet. To express any other opinion would be a mockery of science.

Of course, there always is a microscopic chance that H1 might get disproved tomorrow, and that H2 might resist the attempts at falsification. But until that happens, treating both hypotheses as equal is definitely NOT how actual science works. And it is good that it does not.

In actual science, there is something positive you are allowed to say about H1. Something that would make the strawman zealot of simplified Popperism (e.g. an average teenager debating philosophy of science online) scream about "no proof ever, only disproof". The H1 is definitely not an absolute certainty. But there is something admirable about having faced many attempts at falsification, and surviving them.

I've not read Popper directly, so I'd be interested in his actual argument on this.

But, I wonder if you can describe H1 as being a stronger hypothesis than H2 by virtue of withstanding more and higher quality attempts to disprove it?

"Withstanding more arguments" can be gamed by throwing thousand of silly arguments at your favorite hypothesis. And "higher quality" is the part people would disagree about.

I think that when people are essentially honest and trying to find out truth, they can agree on reasonable rules. But there is no way to make the rules simultaneously philosophically satisfactory and bulletproof against people who are willing to lie and twist the rules in their favor.

For example, in real life you usually cannot convince crackpots about being wrong, but that is okay because at some moment everyone just ignores them. If you try to translate this into a philosophical principle, you end up with something like "argument by majority" or "argument by authority". And then you can have Soviet Union where scientific progress is often suppressed using these principles. But what is the alternative? No one can ever be ignored unless you disprove their hypotheses according to some high standard? Then the scientific institutions would run out of money as they would examine, using the high standard, the 1000th hypothesis of the 1000th crackpot.

This is an age-old domain of thought known as philosophy of science [0]. Although, by prepending your post as "meta", perhaps you are already aware of it.

I should add: As a human being, it is probably impossible to separate the scientist from the philosophy in which they explore, proceed with, and promote their work. In some cases, it might not be something they are even aware of. Instead, the scientific system (as a sort of world institution) should itself be designed to always seek out and protect truth, regardless of prevailing contemporary knowledge.

[0] https://en.wikipedia.org/wiki/Philosophy_of_science

> Your goal as a scientist is to devise experiments that can disprove a claim about the natural world.

If this claim was true, it would disallow science to make true claims, because no experiments can disprove such claims. Truth is a delicate matter and can't be handled by simple methods. Questions may not be settled, but they can be difficult to challenge.

> it would disallow science to make true claims

Isn't that exactly how science work? It does not make true claims. It produces statements with disclaimers. If this and this then Y is true, as long as we don't observe Y.

You cannot use the scientific method to definitely say: "X is true".

Yes, that's exactly how it works. Every scientist I've ever asked has stood by that. Science dispels untruth.

Reply on news.ycombinator.com