What Scientific Ideas Are Ready for Retirement?

Every year we look forward to the Edge Annual Question, and as usual it’s a provocative one: “What scientific idea is ready for retirement?” Part of me agrees with Ian McEwan’s answer, which is to unask the question, and argue that nothing should be retired. Unasking is almost always the right response to questions that beg other questions, but there’s also an argument to be made in favor of playing along, so that’s what I did.

My answer was “Falsifiability.” More of a philosophical idea than a scientific one, but an idea that is bandied about by lazy scientists far more than it is invoked by careful philosophers. Thinking sensibly about the demarcation problem between science and non-science, especially these days, requires a bit more nuance than that.

Modern physics stretches into realms far removed from everyday experience, and sometimes the connection to experiment becomes tenuous at best. String theory and other approaches to quantum gravity involve phenomena that are likely to manifest themselves only at energies enormously higher than anything we have access to here on Earth. The cosmological multiverse and the many-worlds interpretation of quantum mechanics posit other realms that are impossible for us to access directly. Some scientists, leaning on Popper, have suggested that these theories are non-scientific because they are not falsifiable.

The truth is the opposite. Whether or not we can observe them directly, the entities involved in these theories are either real or they are not. Refusing to contemplate their possible existence on the grounds of some a priori principle, even though they might play a crucial role in how the world works, is as non-scientific as it gets.

I’m also partial to Alan Guth’s answer: “The universe began in a low-entropy state.” Of course we all know that our observable universe had a relatively low entropy at the Big Bang; Alan is making the point that the observable universe might not be the whole thing, and the Big Bang might not have been the beginning, so it’s completely possible that the universe as a whole was never in what one might call a “low-entropy” state. Instead, starting from a generic state, entropy could increase in both directions, leading to a two-sided arrow of time. This has been one of my favorite ideas for a while now, and Alan and I are writing a paper with Chien-Yao Tseng that examines toy models with such behavior.

Here are some other interesting/provocative answers, picked unsystematically out of over 100,000 words overall. Remember that the titles are what the person wants to retire, not something they’re in favor of.

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81 Responses to What Scientific Ideas Are Ready for Retirement?

  1. Doc C says:

    Either science is a tool to answer practical questions, or it is a tool to satisfy our anxiety over the uncertainty we experience in our existence. It can’t be both. Falsifiability makes science practical rather than psychotherapeutic.

    Put another way, In deciding to spend our money, how much should we devote to speculative imagination, and how much to practical solutions? Does it really matter how well we understand string theory if its not going to be testable or yield practical applications in any foreseeable time? Are there better problems to focus on? Who gets to choose, the academics, or the indigent?

  2. Jack says:

    I’m glad you point out this is meant to be provocative because I have a hard time believing you are genuinely against the idea of Falsifiability (assuming *your* understanding of it is sufficiently nuanced).

    Falisifiablity is as much about improving theories as it is about demarcation. I’ll take for granted you are an empiricist and believe hypothesis are only that until they can be confirmed by evidence (especially theoretical physics!). They must also have some predictive power.

    The problem with relying solely on confirmation is that many hypothesis can stand up to endless confirmation if you are only looking in one place. To really make your theory strong you need to search for evidence which could refute it. For example, edge cases. The classic example of “water boils at 100c” is a hypothesis and you can test it a million times at sea level. Every time it will be confirmed. It’s not until you take the experiment to the top of Everest and “break” (falsify) it do you truly begin to learn and find the limits of the theory.

  3. Ron Murphy says:

    Doc C,

    Why can’t it be both, to the same person, or either to different people? I’d have thought it was both. Some people may start out in science wanting to satisfy uncertainty (curiosity rather than anxiety – why anxiety?), but in a science career can change the focus to practical questions. I guess the nature of theoretical physics/cosmology retains the quest for understanding more so than much applied science which is more about practical answers.

  4. Jack says:

    Ron, it’s an epistemological question. Do you really “know” anything if it cannot ever be confirmed or make testable (empirical) predictions? In my opinion you cannot. Empiricism is king. Therefore if you are doing purely theoretical science that can NEVER be tested in practice I would say you are no longer searching for knowledge. At which point its no longer science.

  5. Brett says:

    Danny Hillis : I’m immediately turned off by the phrase “we humans”…

    the rest of the links are taking an extremely long time to open.

  6. WT says:

    It is unclear what qualifies Nina Jablonski to urge that we ignore almost the entirety of genomics and biomedical research as people “seeing what they want to see.” A more unscientific attitude would be hard to imagine.

  7. miller says:

    Edge is down, but I already agree with your article. It’s worth knowing that falsification was basically proposed as a solution to the problem of induction, and is meant to replace inductive reasoning. IMO, falsification makes no progress in solving the problem of induction, and is nothing but a clunkier version of inductive/bayesian reasoning.

    The other thing is that though scientific theories must ultimately be subject to empirical investigation, I don’t think it’s necessary for this to be true of every single nut and bolt of science. Scientific practice contains both induction and deduction, and there can be entire careers which focus only on deduction.

  8. phil h says:

    Im very keen to read the new paper, when do you think it will come out?

  9. Brett says:

    not to get off topic here, but Doc C, you can do whatever the fuck you want in life if you can find someone who will pay for you to do it.

    Bill Gates made billions in the tech industry so that he could try to eradicate diseases in arguably the most disease ridden regions of the planet. Bill Gates can do whatever the fuck he wants to do with his $50 Billion because “WE” have no say in what he does with that money. We can donate money to the Bill and Melinda Gates foundation if we choose to do so, as could the government of any country.

    Since understanding String Theory doesn’t cost a damn penny, I’d say the freedom of choosing what you do with your career and/or free time is a decision that every individual is granted the right to. If you’re focus is string theory, then chances are you get paid in various other practices.

  10. Bob F. says:

    Not physics, but psychology: I still see many people quoting Sigmund Freud, even though most of his findings have been shown to be wrong, or even harmful. Of all the scientists with overturned theories, Freud seems to have the longest-lasting and unwarranted prestige.

  11. Platohagel says:

    If you have a location in the past, and you are trying to describe the energy that makes up that past , I think you have to keep looking even when you come up against the horizon? So the attempts to describe the interior and ways to approach it are still necessary. Confirmations have been made up to this point, and a method for examination is still recognized.

    Whether or not we can observe them directly, the entities involved in these theories are either real or they are not. Refusing to contemplate their possible existence on the grounds of some a priori principle, even though they might play a crucial role in how the world works, is as non-scientific as it gets.

    So would we say in this respect this is non scientific? Just wondering?


  12. Bruce Caithness says:

    Karl Popper replaces the focus on the justification of beliefs with the process of forming critical preferences for theories or policies formulated to solve problems. Better theories explain more than lesser theories, predict more precisely, articulate with other theories and they stand up to tests.

    With respect to the latter, we should attempt to state our claims in a form that will invite refutation by existential statements (if true). Thus falsifiability is a logical property of a statement. Falsification is the process of demonstrating that a proposition has been falsified. Unlike the decisive logic of the process, the real-world process of falsification can never be decisive due to the Duhem problem, the uncertainty of observations and the many more or less disreputable ways that people can protect their views.

    Thus, science is that branch of the arts that presents its explanatory claims in such a form as to be testable against the world. The demarcation between science and non-science has nothing to do with methods of discovery or technologies of discovery but rather with the perpetual and normative requirement to make scientific statements logically amenable to being proven wrong, even if in practice it is a matter of decision. Furthermore, if one is asked what is the aim of science, it is to explain whatever one deems requires an explanation. It begins with problems, not with data. How can minds or their technological surrogates even perceive data if they do not possess modifiable expectations or propensities to solve problems?

    Furthermore, building tools is not the same as doing science. Scientific theories may be instruments but they are not only instruments. They explain. A shovel or an electron microscope is not true or false, a scientific theory can be; mind you any claim to be true is only tentative – otherwise it is not science! Our conjectures come first as in all arts. Let us praise imagination, but remain humbled by our propensity for error. It is the humility of science that gives us hope that we will not be consumed by technological hubris.

    Discard the norm of trying to make scientific statements able to be proven wrong if you like? What will you replace it with?

  13. Doc C says:

    1. You are way off topic.
    2. We all paid handsomely for the development of string theory in the taxes that went to supporting research grants and to institutions of higher education who used that money to subsidize faculty and grad students who work on it.
    3. The question I addressed regarding falsifiable science is not whether anyone can do anything they want with their money, but how groups of people who organize into a cooperative society should decide how their common pool of resources are used.
    4. The use of vulgarity does not improve an argument. It generally reveals a lack of one.

  14. Pingback: Time to ditch falsifiability? | SelfAwarePatterns

  15. Ahab says:

    You can’t prove that you’re not a BB, just like you can’t prove that you’re not dreaming, or being fed false information by a whimsical demon. Nor can you make any progress on understanding the world in reliable ways if any of those scenarios is true. Therefore, we work to develop models in which they are not true.

    This is how you previously rejected the theory that I’m a Boltzmann Brain dreaming of a non-thermal-equilibrium universe. A theory that actually satisfies both of your “definite” and “empirical” criteria. It’s “definite” because it “say[s] something clear and unambiguous about how reality functions”, and it’s “empirical” because it of “its ability to account for the data”.

    Whether or not we can observe them directly, the entities involved in these theories are either real or they are not. Refusing to contemplate their possible existence on the grounds of some a priori principle, even though they might play a crucial role in how the world works, is as non-scientific as it gets.

    Question: If the dog didn’t bark in the night-time, should we take that as a clue, or should we get rid of it?

  16. Dan says:

    Pure mathematics has propositions that have not been proved
    or disproved and as such are an enjoyable challenge for the professional or amateur. Number theory is replete with such unproven (e.g. Goldberg’s Conjecture) nuggets that await being proven but are yet open to being shown a counter example. But the sciences per se seem to be more susceptible to pressure from non-science agendas
    then the science’s supporting mathematics. This was true in Galileo’s time as well as now. So I see Popper’s rule as a bulwark against such pressures.

    Whenever I hear the phrase ‘the data show’ the expectation is that one cannot argue against ‘the data’, as if that itself were irrefutable and therefore the argument is moot. The old saying among statisticians was ‘torture the data until it confesses’. I have been involved in research as a support for scientists and they can get quite opinionated as any. Being rational and unbiased is an ideal goal, as difficult for the scientist as the lay person.

    Current topics that are highly politicized such as; differences between the sexes, IQ and race, the concept of race, global warming (now called climate change), et al. Can a researcher even pursue, unbiasedly, such fields without being attacked. Hardly.

    So for me, as a former practicing statistician, my concern is that the scientist has many pressures to assume a theory to be true ipso facto. To discard the Popper Rule is to weaken the scientific community’s defense from non-scientist pressure to conform to the zeitgeist.

  17. John Duffield says:

    I started reading but was stopped in my tracks when I got to this in the second paragraph:

    “We knew, for example, that the electron mass is the same everywhere in the observable part of the universe, so the obvious assumption was that it must take the same value everywhere, it is just a constant of nature”.

    That’s wrong! There’s the mass deficit or mass defect. The electron’s rest mass varies with say gravitational potential. If you drop a 1kg brick into a black hole, the black hole mass increases by 1kg, no more. And on the way in the brick was moving very fast. Its kinetic energy comes from its rest-mass energy. I also noticed Freeman Dyson saying wavefunction isn’t real. He should talk to Jeff Lundeen who said this:

    “…So what does this mean? We hope that the scientific community can now improve upon the Copenhagen Interpretation, and redefine the wavefunction so that it is no longer just a mathematical tool, but rather something that can be directly measured in the laboratory.”

    I have to say Edge sounds like a promotional clique for people who want to tell everybody else that they’re the elite.

  18. robert price says:

    Ian Mcewan is right… retire nothing …but we can reasses and think things over from new perspective.
    Much trouble in cosmology comes from years of missunderstanding …miss interpreting.
    Newton went as far as he could …or dared . Einstein did the same
    an apparent attraction … curved space time …
    all just words trying to explain observations

    We need to re think Gravity from the universal law on wards .
    What masses are doing .. in producing tjis force ..
    they do not create gravity on their own .
    Force comes from Energy .. the energy in space …from all directions .. radiations and partickes .

  19. John Deer says:

    A theist can can make the same argument about yhwh or the spaghetti monster.

    In the realm of physics, the math can support e.g. tachyons. Does it mean we need to accept them as real? If not, why not?

  20. Andy Odell says:

    I find the falsifiability argument very useful, for myself and in my work. At work I often get fundies arguing for Intelligent Design or Young Earth Creationism. My approach is to ask them if there is anything that would convince them they are wrong. They usually look suspicious (of the trick question), and agree there is not. (I think they feel this strengthens their argument.) I can then reply that there is no point in talking further.

    There are certainly things that would change my mind. If the heavens opened up and a booming voice said, “I didn’t use evolution!” – that certainly would, even though I seriously doubt it will happen.

  21. It is tempting to think that science needs the precision of philosophical analytics, as science (especially physics) make improvements that far exceed a clear path to falsifiability. This is however what makes Popper even more relevant now than when he proposed demarcation. The further we step into mathematical concepts as a pure explanation of physics without the potential for observation, the less likely we are to further fundamental truths. It is good that the best minds are working on the most complicated problems from a standpoint which is not limited to falsifibilty, however letting our notion of a physical reality float endlessly into intelligent mathematical concepts, leaves us unable to make the steps necessary to provide a practical understanding of stuff, and therefore loses experimental rigor at the expense of mathematical rigor. Both require and should have rigor. Perhaps Popper is more relevant now than ever.

  22. “I have to say Edge sounds like a promotional clique for people who want to tell everybody else that they’re the elite.”

    It certainly does have a waft of that about it.

  23. A related question is “What idea has made the transition from ‘interesting’ to ‘useful’?” Inflation?

  24. DEL says:

    Dear Sean, I’m flabbergasted! Here’s your 2nd paragraph with only a few point modifications:

    “The truth is the opposite. Whether or not we can observe Him directly, the Creator involved in this theory is either real or He is not. Refusing to contemplate His possible existence on the grounds of some a priori principle, even though He might play a crucial role in how the world works, is as non-scientific as it gets.”

    No further elaboration is called for. But let me only add that, unlike in mathematics, nothing in science is really definitely provable. (That rigorous proofs do exist in mathematics only highlights the fact that math is tautological in nature.) So if one exempts oneself of falsifiability, one is left with nothing but speculation. It may be a very “scientific” speculation, construed as science due to the question asked being conventially categorized as scientific, or because it uses exclusive math tools and layperson-dazzling lingo typical of science, yet it is speculation all the same.

    And one more thing. Science fights for its life—against antiscience, pseudoscience and post-modernist relativism—in the public opinion arena. This kind of transgression provides the enemy with ammo: New Agers may rightly ask “Why, then, are you any better?”

  25. John Duffield says:

    Well said DEL. And Dan and Andy and Matthew and Doc and Jack.

    Sean, if you retire falsification you retire science. I’m not happy with that. And a lot of other people won’t be either. This is not going to do your career any good at all.

  26. Neil says:

    I doubt that you want to retire falsifiability. You just don’t think it is a requirement for an idea to be science.

  27. Adam H says:

    I am not bothered by falsifiability. It is one solid criterion but not the only one. I am more concerned of this blatant gimmick to redefine the scientific method to suit theories which fail to meet any of its criteria. It’s not going to fool anybody. If we reach a point where the scientific method fails, then we say the scientific method can not tell us anything beyond this point here. At that point, we can use other means to explain what’s going on but we don’t pretend that we are conducting scientific inquiry because we’ve cleverly just redefined what we mean by science.

  28. Mike D says:

    I’m reminded of Stephen Hawking: “It’s meaningless to ask what is real, only what agrees with observation.”

  29. CPV says:

    “Amanda Gefter, Andrei Linde, and Seth Lloyd all suggest that we get rid of the idea of a unique universe, each from a slightly different perspective. Sorry, universe: the tide is turning against you.”

    I suspect the universe is still sleeping quite well at night with such weak arguments arrayed against it.

  30. Reginald Selkirk says:

    Whether or not we can observe them directly, the entities involved in these theories are either real or they are not.

    That’s setting the bar very low. Santa Claus is real or he is not. The easter bunny is real or it is not. Invisible pink unicorns are real or they are not.

    Does science tell us anything about whether these things are real?

  31. Doc C says:

    So if we can’t touch it it can’t be real? If ‘Santa Claus” inspires a child to buy a toy for an indigent child (because Santa can bring that child toys, but his family can’t, so the first wants to help Santa), is Santa real? He has a real effect.

  32. Jens says:

    If you drop falsifiability, an infinite number of theories will all be right. On what new basis will you know the right one?

    “Darkness gathers. The demons begin to stir.”

  33. Ken Gayley says:

    Sean Carroll is an excellent theorist, and I wish I had his deep understanding of string theory and most of the rest of physics for that matter, but he’s really wrong here. And it’s quite clear why he’s really wrong– what does he think is the actual process whereby “nature is the ultimate guide”? Falsifiability, obviously! Seriously, we have a huge body of evidence from which to answer that question, it is called the history of physics. In that history, it is completely demonstrable that the process for discarding theories is not coming up with ones that a consensus of people like Sean Carroll prefer for personal reasons, they get discarded for only one reason: they got falsified, because they were falsifiable. What happens to what is unfalsifiable is also a matter of record: it becomes folklore.

    A classic example of this is the geocentric model of the solar system. For millennia, that model was adopted because the consensus of the Sean Carrolls of the day was that the stars could not be so far away that they would not appear to move, it just didn’t make sense to them for the universe to be built that way. So if personal preferences, rather than falsifiability, ruled the day, we’d still be teaching the geocentric model. But when Galileo saw that Venus went through phases, it meant Venus had to orbit the Sun, period, end of debate. Thank goodness for falsifiability!

  34. mike says:

    Dear Mr. Carroll
    I was wondering if you can answer the question or consider writing an article on the subject:

    Has dark energy or dark matter changed in the life of the universe?
    Is it possible for one to slowly change into the other over the life of the universe?
    For instance, if dark energy can change into dark matter, then perhaps the universe will slow it’s expansion, perhaps even stop it’s expansion, reverse and a big crunch will occur.

    Is there any evidence or reason (beyond my pure conjecture and perhaps wishful thinking) for this to be?

    Yours truly

  35. AI says:

    Sean your answer is bad and you should feel bad.

  36. C.Takacs says:

    Mr. Carroll,
    You might seriously consider writing a retraction, or something that perhaps clarifies your position to some degree better than you have. Your position on jettisoning falsifiability from science is not logically sound, namely because you are abandoning the underpinnings of logical argument itself, without which there is no science.

  37. Jesper says:

    Dear Sean Carroll

    In your ‘Edge’ piece you advocate for the retirement of ‘falsifiability’ and yet you end your piece with declaring Nature our ultimate guide. To me, this is completely self-contradictory. If Nature has no way of saying “you are wrong!” – which is falsifiability – then to me it appears you’re taking it along, not as a guide, but more like a Teddybear to hold your hand.

    As a physicist I’m deeply troubled by seeing someone in a significant position advocating the abandonment of falsifiability. Yes, it might be that string theory is correct without being falsifiable. Yes, it might be true about the multiverse too. And it might be true about God and about the giant teacup theory. But for Science to have any value, we have to stick to the perhaps limited position of only accepting statements and theories, where Nature is left a right of veto. Otherwise we’re not doing Science anymore.


  38. DEL says:

    Falsifiability is just one in a whole set of requirements. Others are, e.g., internal consistency, mathematical distinction, Occam’s Razor compliance and, lest some priviledged Edger might suggest to retire it, agreement with the complete existing body of experimental and observational results to within their respective error bars.

  39. Pingback: Shtetl-Optimized » Blog Archive » Retiring falsifiability? A storm in Russell’s teacup

  40. Hi Sean,

    It’s been long time since I publicly, sort of, insulted you—I mean, online. (I vaguely remember the development of a facility to shuttle in between the universe(s (!)) of multi-verses. … Come to think of it, I got it almost right.)

    Never mind.

    With that (Marathi) “namanaalaa ghaDibhar tel” [rough English sense of the term even if not the translation: When you pour a pound of oil to the lamp of the God right before the beginning of a prayer… [meaning: you are so stupid, such a newcomer, you wouldn’t even know how to make a candle burn *all* through the night at a church]], even without the full of your post or your readers’ replies, let me answer in brief:

    Instantaneous Action at a Distance.

    We could do without it.


  41. Bruce Caithness says:

    Maybe it is worth recognising that Popper’s idea of falsifiability was a vast improvement on the positivist attempt to separate science from non-science in terms of sense or meaning. Popper is not saying that non-falsifiable statements are meaningless nor even less true than scientific statements. For instance realism and anti-realism are metaphysical and cannot be refuted. This does not mean they are beyond argument. Popper liberated metaphysics from a narrow positivist treatment.

    Popper would say: We explore the universe by conjecture and we explore our conjectures through logic (rationality filters our guesses). Falsifiability is a logical property of scientific statements.

  42. Pingback: Methods: testing an idea

  43. DEL says:

    For many years I have been an e-mail subscriber to Edge and I usually read most of the monthly conversations there. I made it a rule, however, to skip the annual question and all the answers given to it, for three main reasons: 1) The sheer volume of them. 2) The mostly mediocre quality of the answers, which reafirms what Buddhini Samarasinghe wants to get rid of:

    ◾Buddhini Samarasinghe, Scientists Should Stick to Science.

    3) If I’m technically prevented from even proposing an interesting answer, since Edge excludes mortals such as I, (i.e., those that do not cater to Mr. Brockman’s publishing business,) then I’m not interested in their tedious answers—let them read one another ad nauseam.

    Several years ago I attended a Nobel laureates seminar in the Technion, Haifa. One of the speakers was a co-winner of the 1991 prize for the invention of the patch clamp neuroscience lab technique. He told the audience that, being a rather shy person, he had hesitated whether to accept the invitation. Consulting his mentor, the latter had told him briskly: “A shoemaker should be making shoes.” (But he had accepted anyway.)

    Take, for example, the first answer, by

    ◾Danny Hillis, Cause and Effect.

    As an example for the unsoundness of the cause-and-effect concept, even in classical mechanics, he brings up the case of Newton’s 2nd law, F=ma, where one cannot say which of the three quantities is cause and which are the effects. But this only shows a misunderstanding of that law, which is nothing but a definition of inertial force (mass being defined, as by Newton himself, to be “the quantity of matter,” [Principia, Book 1, Definition 1]), and a failure to realize that causality entails that the events involved be time-sorted. Incidentally, in the LHC, which is the cause and which is the effect, the hadrons colliding or the Higgs boson signature detected? If you know the answer to that you know also what to think of Hillis’ suggestion.

    Yes, shoemakers should be making shoes and scientists should stick to science.

  44. policrit says:

    I am troubled by the treatment of falsifiability as a single theory. There are strong and weak versions with many gradations. Is the theory not falsifiable right now with present methods? In the near future with plausible methods? Eventually with purely theoretical methods? Probably unattainable methods? Not falsifiable with any conceivable test? I would submit that at least the last is certainly a valid notion.

  45. From reading the enlightening comments, the post are against your idea of rejecting the idea of falsifiability as a scientific concept to reject. The posts give excellent arguments against your proposed idea. Floating out such ideas is a wonderful way to learn.

    Science is based on experimental data. Theoretical and experimental physics ultimately make their advancements based upon data. Theories need to be tested with data. If a theory cannot be tested against data it is not science, it is philosophy. A scientific theory must have the ability to be shown wrong with experimental data.

  46. The practice of Science has always been ad hoc, a gradual groping
    for a way of proceeding that seems reasonable– “falsifiability”
    is one an attempt at firming this up, and it seems funny to me
    that so many people here are trying to treat it as though it’s
    some sort of primary revealed doctrine.

    Falsifiability itself isn’t a scientific idea, right? Most of us
    would call it a philosophic principle (after all: “Is
    falsifiability falsifiable?”). So if it strikes you as a
    critically important idea, you’ve already conceeded that there
    are things outside of science that matter.

    An attempt at advancing science like “string theory” might not be
    precisely “scientific” (as of yet) if you’re a true believer in
    falsifiability, but in that case you could just put string theory
    in another category (“proto-scientific”?). String theory need
    not be abandoned as Unscientific and Unclean.

  47. Jesper says:

    @ Joseph Brenner.

    “… So if it strikes you as a critically important idea, you’ve already conceeded that there are things outside of science that matter.”

    – yes, of course! The concept of falsifiability – which simply means that you’re giving Nature a right of veto – does not mean that only falsifiable statements are worth while considering. It simply means that only (in principle) falsifiable statements can be called scientific theories.

    Most things that matter is outside of science – obviously.

  48. Richard says:

    If you have a (mathematically) complex theory which currently does not make predictions, but you think it will after 1 year of research, is it scientific? What about 5, 10, 50, 100 years? At what point does it become nonscientific?

  49. Bob Iles says:

    For further info on this exciting topic cf. arXiv:1210.8144v1.

  50. Jesper says:

    @ Richard. In my opinion, to call a mathematical framework (or something else) a theory requires predictions (they may not be practically verifiable). If your framework doesn’t make predictions, then it may of course still be very interesting and worthwhile pursuing, and it is still scientific – its just not a theory.

  51. Haelfix says:

    These comments all miss the following very important point. Namely that the idea of a multiverse IS falsifiable in principle. If you make a collider and create the inflaton particle, you immediately know detailed properties about the physics of the very early universe, like whether it is in the eternal class of potentials or not. From that point on, you likely know whether or not there really is a multiverse of causally separate regions.

    Now this is probably not falsifiable in practice because we can’t create accelerators with that type of energy, but it is falsifiable in principle and that is what Popper was talking about. I dare anyway to come up with an argument that says that this is not science, and then contemplate how silly they sound when faced with all the impossible experiments that latter became possible. Does every idea preceding these experiments not count as science?

  52. Doc C says:

    @ Haelfix, What is different about being falsifiable in principle but not in practice and having no way to provide evidence for a belief? For example, those who believe that God will return to the world at the end of time can say that God is falsifiable because he will be falsified at the end of time if no God actually shows up. We can’t know the facts about the end of time in practice, but we can in principle; we just have to wait for it.

    Humans have acted on non-falsifiable beliefs for millenia, and we are still here. Maybe we don’t always need certainty to successfully interact with our environment. However, falsifiability is the only way we gain certainty by successfully testing our interactions.

  53. DEL says:

    @Doc C:

    “… falsifiability is the only way we gain certainty by successfully testing our interactions.”

    Sorry, but the whole point of falsifiability is that there is no certainty. You can only falsify a wrong theory but you can never be certain of one you failed to falsify.

  54. Doc C says:

    @DEL, Yes, that was sloppy. I should say the only way to gain IN certainty, or become relatively more certain. However, the true lack of certainty of any theory or law, taken to its extreme, is not a useful way to do science, with or without falsifiability.

  55. Bruce Caithness says:

    My reading of Popper is that a falsifiable statement is vulnerable to empirical refutation. Even if it fails a test there might still be debate about whether the theory is actually wrong e.g. due to errors in the test environment.

    Popper has a sophisticated view of the rules of the game of science. The game of science is in principle without end and a practitioner no longer plays the game of science if he or she chooses to evade critical analysis or further empirical testing of theories.

    Certainty is perhaps an over-used word which tends to focus on belief rather than truth, even if truth is hard to find.

  56. Haelfix says:

    The Higgs boson was a theoretical idea that was written down 50 years ago. It was not a falsifiable idea at the time, so according to this silly dogma we must not consider it science. For that matter, all GUT theories, theories of dark matter and for that matter almost all of modern HEP-PH must not be science either.

    Popper knew perfectly well that science didn’t always have to be falsifiable now. Instead he was interested in refuting statements like ‘god is an invisible spaghetti monster that hovers over my room’. The latter statement can never be disproved, even in principle. Conversely, the multiverse might be verified tommorow (for instance by observation of a bubble collision) or alternatively it might be refuted tommorow if strange features appear in the next CMB experiment that shows deviation from inflationary expectations, and certainly if we had a big enough accelerator we would know with almost complete certainty.

    Of course, scientists don’t care one whit about whether or not something adheres or not to one dead philosophers ideas about propriety, instead we have a great deal of mathematical evidence as well as circumstantial evidence for an idea, therefore we are allowed to study it.

  57. Mohammed Patel-Gonzales says:

    Dr. Carroll – I know this is off-topic but I figured you’d get a kick out of this in any event, & that is because I was able to understand something because of what you mentioned on the blog some while back now.

    Anyway, I’m reading an urban fantasy by Tad Williams called The Dirty Streets of Heaven & in it, one angel says to another something like the following: “He even asked me how A & B work, which is kind of like asking a Juggalo to explain magnetism.” The book came out in 2012 but I never would’ve understood what the author was talking about here if it hadn’t been for your earlier comments on the idiotic ignorance of the Insane Clown Posse concerning magnetism & such, which presumably extends to their fans, called Juggalos, as well. Oh, & BTW, the FBI recently deemed the Juggalos to be a criminal gang so presumably now they can be shot on sight by anybody. Good news!

  58. DBachmann says:

    I would humbly suggest that if something “might play a crucial role in how the world works”, it is a fortiori also observable, at least indirectly, and statements relating to it are in principle open to falsification. I seem to remember that even string theory once had a motivation based in observables, specifically the desire to understand gravity, which I assume we are all experiencing as we speak.

    Also, I see nothing wrong with the statement that “the universe began in a low entropy state”, as you say yourself in the linked post, “the fact that entropy increases defines the arrow of time”. The statement is true to the point of being tautological, so I suppose you could argue it is unhelpful based on that. But arguing against it devolves into a semantic game on the meaning of “beginning”.

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  60. There are category issues here. I would say that “nonfalsifiable physics” is really “mathematics”.

  61. Sean, I strongly disagree with your position on falsifiability, for many of the same reasons that others have mentioned before. Two things I would like to point out though:

    – The criteria you suggest as replacements, that a theory should be only “definite” and “empirical”, are not enough to exclude a vast swathe of creationist ideas that I’m sure you would agree are not scientific. Therefore falsifiability is still necessary.

    – I think the point you were getting close to making, but did not quite articulate, is that the definition of the word “falsifiability” should be slightly expanded to incorporate the notion of Bayesian probabilities rather than simple yes/no rejections. In this case the multiverse may yet turn out be (but is not guaranteed to be) a “falsifiable” idea. But if it doesn’t, it is still not science.

    I can’t fit much more than that summary in this comment box, but I’ve fleshed out these ideas a bit more here if anyone is interested.

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  63. colnago80 says:

    Speaking of ideas that should be retired, does Prof. Carroll have any comment on the latest from Steven Hawking that black holes don’t exist?


  64. DEL says:

    Colnago80’s point does bear on the issue of falsifiability discussed here. Specifically, we may ask whether Steven Hawking’s kind of work is or is not science. Surely, by mathematically fiddling with the equations of GR and QM, doing it in an academic setting and on Isaac Newton’s chair, uploading papers to arXiv, etc. etc., the most celebrated physicist of our time must be doing something scientific, mustn’t he? I’d say yes, of course, but these are only superficial, social-cultural hallmarks of science.

    Here’s what I understood of the problem Hawking is nowadays dealing with: what does a free-falling object encounter just past a black hole’s event horizon, a blissful continuous glide down or a sudden violent incineration?

    By definition, what happens beyond the event horizon is in-principle a secret. However, the behavior of matter and radiation just outside the event horizon might be linked by theory to the answer to that problem. So, to decide whether Hawking is a scientist or a science artist—a noble-enough occupation, in my view—I would like to know whether there might exist some unique observable prediction associated with the sought answer or with some spin-off result. If there is, and if it is observed, then Hawking might even be noticed, at long last, by the physics Nobel prize committee.

  65. Pingback: Black holes, bananas, and falsifiability. | An Island in Theoryspace

  66. Marcos Hardy says:

    Popper’s “falsifiability” is obsolete only if you apply it indiscriminately to determine Science from non-Science instead of use the concept to understand the workings of scientists in the real world. Every time a scientist experimentally tests an hypothesis he is falsifying a scientific idea, once the hypothesis has been successfully tested and published, then other scientists will attempt to falsify it through replication, and so forth, until a theory is established, which in turn will be tested (falsified) ad infinitum. Examples of this type of falsification abounds, from cold-fusion to the memory of water to cite extremes. Freud did not “discover” the unconscious but in his research of the operations of the mind produced a testable model of its dynamics in shaping our behaviors, thus questioning the reality of “free will.” Today, neuroscientists are producing increasingly reliable experimental tests of Freud’s models; i.e. Freud’s model, one of Popper’s examples of “unfalsifiability,” is now becoming amenable to falsification. And, please, do not confuse Freud’s scientific research efforts with the corrupt voodoo clinical work of the psychoanalysts. Einstein’s theory of gravity was successfully tested through Eddington’s 1911 measurements of starlight deviation during a total solar eclipse. Nonetheless, astrophysicists are getting ready to test it (falsify it) once more with a pulsar and two stars (cf. Adrian Cho in Science (2014) vol. 343 pp 126.) Has not Einstein’s theory of gravity achieved total “truthiness” already? Why does it need constant testing (falsification)? Well, Science advances, also, through falsifiability. That “string theory” (is it a theory already?) and “multiverses” (typical examples of what Horgan called “ironic Science”) are not currently amenable to falsifiability speaks of technological shortcomings in our current state of development but not necessarily in the future and scientists might become able to eventually falsify them. Dark matter and energy are conveniences (as was the flogiston once) to explain cosmic phenomena but scientists are putting an extraordinary effort to test (falsify) the hypothesis. One might even say that Marxism, another of Popper’s bête noirs, was falsified through the social experiments of the post-war. I believe that the concept of falsifiability is an extremely useful epistemological concept to understand the developmental operations of the Sciences in the real world. The problem does not lie with Popper’s falsifiabilty but that, like Kuhn’s “paradigm,” it has been horribly misused and mangled. To apply an unfalsifiable cliché, keep the baby and start discarding the dirty bathwater. Keep falsifiability current and apply it correctly.

  67. Michael Allen says:

    How does one go about showing a statement is falsifiable anyway? Wouldn’t that in itself be fundamentally unfalsifiable?

  68. Bruce Caithness says:

    Falsifiability is but a logical property of a statement. The practical attempt to refute a universal statement by showing a basic statement to be wrong is called falsification.

    The propositions of concern to Popper were universal statements with a form such as “all swans are white”. This is in a falsifiable form in as much it would be nullified by the statement (if true): here is a black swan.

    Whether the basic statement “here is a black swan” is true requires a decision which, to forgive the pun, may not be black or white.

    Popper was not talking about “naive” falsification. Whether a statement is decidable (whether we believe we can prove it true or false) differs from the question of its truth.

    “I mean by ‘rationality’ simply a critical attitude towards problems – the attitude of conscious, critical, error elimination” (Popper)

  69. mpc755 says:

    The whole notion of “falsifiability” is meaningless in mainstream physics.

    The particle does not always travel through a single slit in a double slit experiment.

    How do you falsify the above statement? You place detectors at the entrances, throughout or at the exits to the slits.

    When you do this the particle is always detected entering, traveling through and exiting a single slit.

    The notion the particle does not travel through a single slit is refuted by the evidence. It’s been falsified.

    So, what does mainstream physics do? They ignore the physical evidence which refutes the notion the particle does not travel through a single slit and state that something else occurs when you don’t detect the particle.

    What is that something else? Well, now mainstream physics can make up all sorts of stuff about a multiverse or many worlds or whatever nonsense it wants because you can’t falsify made up nonsense.

    The notion the particle does not travel through a single slit is falsified by the physical evidence.

    However, mainstream physics is so fucked up it can’t understand something as simple as the particle always being detected entering, traveling through and exiting a single slit in a double slit experiment is evidence the particle always travels through a single slit. It is the associated physical wave in the aether which passes through both.

  70. DEL says:

    You don’t understand: one doesn’t try to falsify an isolated statement such as “The particle does not always travel through a single slit in a double slit experiment.” The statement F=ma, in isolation, is also unfalsifiable.

    The complete system of statements, explaining the outcome of both the free and obstructed double-slit experiments, of which the statement ‘the particle travels through both slits at the same time’ is just one component, is the falsifiable content. Similarly, the complete system of Newton’s laws is falsifiable, not any one of them in isolation.

    And you don’t understand: foul language won’t make your arguments more persuasive.

  71. mpc755 says:

    Physics is supposed to be about understanding what occurs physically in nature and the evidence which supports what we think is occurring physically in nature.

    In a boat double slit experiment the boat travels through a single slit and the bow wave passes through both. If the boat is moving fast enough the bow wave will create wave interference upon exiting the slits which will alter the direction the boat travels. If you place pilings at the exits to the slits in order to detect the boat the boat will get knocked around by the pilings, lose its cohesion with its bow wave, and continue on the path it was traveling.

    Is the question the boat does not always travel through a single slit falsifiable?

    When you place pilings at the entrances to the slits the boat is always detected entering a single slit. When you placing pilings anywhere within the slits the boat is always detected within a single slit. When you place pilings at the exits to the slits the boat is always detected exiting a single slit.

    The question the boat does not always travel through a single slit has been falsified.

    Now, just because when you place a screen in front of you so you can’t see the boat double slit experiment and the boat makes an interference pattern on the shore when it is not detected is not evidence the boat did not travel through a single slit. It is indirect evidence it is the bow wave which passes through both slits.

    The fact that mainstream physics is so screwed up it can’t understand the particle always travels through a single slit is the reason for the strong language. Sometimes strong language is appropriate.

    Doing away with falsifiability because mainstream physics is in denial of understanding it is the aether which waves in a double slit experiment is one of those times.

    Do you realize most of the nonsense associated with mainstream physics goes away when you understand aether has mass which physically occupies three dimensional space and is physically displaced by the particles of matter which exist in it and move through it?

  72. mpc755 says:

    The idea which is ready for retirement is the notion of, “in truth, only atoms and the void”.

    In truth, not only is there an aether, it has mass.

    There is no such thing as non-baryonic dark matter anchored to matter. Matter moves through and displaces the aether.

    What is referred to as the the Milky Way’s dark matter halo is the state of displacement of the aether.

    What ripples when galaxy clusters collide is what waves in a double slit experiment; the aether.

    Einstein’s gravitational wave is de Broglie’s pilot-wave; both are waves in the aether.

  73. DrDave says:

    This is a sort of high-tech “lobbying” where one puts the best spin on something, in this case, the spin is applied to a set of ideas that has some serious problems. Part of the process is to exclude valid rebuttal, and to slyly insult those who have a different viewpoint (calling good scientists and thinkers “lazy” and that their ideas are “bandied about” is the worst sort of laziness, the slur).
    The reality is that there are a lot of entrenched academics that currently are not pursuing all avenues of science. This then becomes a story about raw political power, not ideas. Regardless of whether you believe that strings and SUSY are just another form of dreaming (after all, in another universe dreaming might be reality), the result, the plain, hard, cold, light-of-day truth is that other areas of physics, mathematics, philosophy and science have been permanently back-burnered as a result of the successful lobbying of an activist, well-positioned group with an entrenched mindset. This post shows the defense mechanism of this Borg-like structure–or perhaps NOMAD, saying: “I am SUSY, I created the Multiverse”, on a loop (a gravity loop, of course).
    So truth isn’t beauty, and beauty isn’t truth; in this universe, beauty and truth means freeing the system. Free it, and share your theories with others; let others share their theories as well.

  74. mpc755 says:

    Does a tag line of, “in truth, only atoms and the void” mean you do not believe dark matter and dark energy exist?

    Are you suggesting light waves propagate through an empty void?

  75. mpc755 says:

    How do you know the particle does not always travel through a single slit in a double slit experiment?

    You don’t.

    You choose to believe the particle does not always travel through a single slit so you can make stuff up like ‘many worlds’.

    There is evidence of the aether every time a double slit experiment is performed; it’s what waves.

  76. Marcos Hardy says:

    mpc755: you are exhausting everybody’s patience. Call it a day, please.

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  78. Bruce Caithness says:

    “Myth and Metaphysics.

    In his books Objective Knowledge and Conjectures and Refutations, Popper demonstrates brilliantly the roles of myth and metaphysics in the scientific enterprise. Myths represent our human need to expand the horizon of explanation and to find our place in the vast scheme of things. Emphasizing the importance of boldness of imagination in fulfilling this need, Popper suggests that Democritus’ early theory of atoms began as a myth born of a daring imagination.

    Myths sometimes graduate to the status of metaphysics when subjected to sustained and rigorous criticism. Metaphysics is the work we do when we carry out comparative analysis of our cosmological myths and theories. It is our drive to eliminate inconsistencies, to broaden the scope of our explanations, and to provide depth of detail. If there are priests of myth who insist on perpetuating the myths without correction or revision, there are others among us who both subject the myths to criticism and offer rival theoretical explanations. Of late, the term metaphysics has been adopted and used to propagate the uncritical and highly anthropomorphic notions of pop culture. This is not the tradition of rigorous metaphysics of which Popper speaks.

    Far from being meaningless, critical metaphysics and cosmology provide the cognitive background for the growth of scientific theory. Logical positivists failed to see that, without metaphysics to work upon and to refine, science would stagnate. In some ways, science is the metaphysics that succeeded in spawning bold theories which are not only well articulated and critically debated but also observably testable–and by testable, Popper means falsifiable.”

    Joe Barnhart, American humanist (1920-1993)


  79. Marcos Hardy says:

    As much as I admire Popper, let us not forget that he was a dualist “a la Cartessiane.” He did not believe that mind could be the product of matter. Let us keep Popper’s vision of how Science develops and the workings of scientists. His metaphysics have no scientific value, as they are not falsifiable. (Last comment is tongue in cheek.)

  80. Bruce Caithness says:


    One theme of Popper’s output is evolutionary epistemology. Evolution is trial and error. From this perspective, mind emerges from matter but can hardly be reduced to matter. He is an interactionist.

    I have returned to Popper’s name in my comments because falsifiability is one of his themes that has often been distorted in philosophy of science textbooks.

    It is usually overlooked that there were at least six themes in his work. These are succinctly summarized in Rafe Champion’s “A Guide to the Logic of Scientific Discovery” (Kindle).

    Yes, I notice the irony in your last sentence.

  81. Abhishek Khanal says:

    I’m reminded of Richard Feynman,” For those who want some proof that physicists are human, the proof is in the idiocy of all the different units which they use for measuring energy.”