Scientific Debates Are (Mostly) a Waste of Time

The fake table of contents from the April 1, 1986 issue of the Astrophysical Journal. (Click for larger version.)
The fake table of contents from the April 1, 1986 issue of the Astrophysical Journal. (Click for larger version.)

Recently, I acquired a stack of books, papers, conference proceedings, and other scientific memorabilia, including the fake journal table of contents on the right. Though the material varied a lot in content and tone, I noted a lot of things in common: nearly every set of items emphasized a debate that was very significant at one time, but now is pretty much dead and buried. Though it’s intended to be humorous, the first three items in the Astrophysiological Journey (a parody of the prominent Astrophysical Journal) table of contents highlighted a real conflict in the cosmology community.

That conflict was over the rate of the expansion of the Universe. Since the 1920s, we’ve known that most galaxies are moving away from us, and the farther they are, the faster they seem to be receding. Though it took decades for many cosmologists to accept, eventually the evidence convinced the community that these galaxies aren’t actually “moving” in the usual sense, but being carried by the tide of cosmic expansion. The debate highlighted in the first three items of the Astrophysiological Journey was over the rate of that expansion, encapsulated in the Hubble parameter (sometimes known as the Hubble constant).

The Hubble parameter isn’t a speed as such. Instead, it tells how fast a galaxy would appear to be moving away from us as, if we know its distance (or vice versa). Today, the value of the Hubble parameter is approximately 71.2 km/s/Mpc (with some variation in estimates depending on what data you use). That means a galaxy 1 million parsecs away (1 megaparsec, or Mpc) appears to be moving away from us at a speed of 71.2 kilometers per second (km/s), while a galaxy 10 Mpc away would appear to be moving 712 km/s.

However, it took decades to settle the value of the Hubble parameter, and the authors of the first two “papers” in the Astrophysiological Journey were real astronomers striving to be the first to get it right. Alan Sandage was the heir apparent of Edwin Hubble, who (along with the awesomely named Vesto Slipher) first attempted to measure cosmic expansion; Gerard deVaucouleurs’ work was largely with galaxies, so he thought he had a better method than Sandage’s. They each had their partisans and students; the story is told in Dennis Overbye’s excellent book Lonely Hearts of the Cosmos. Conferences were devoted to the debate over the Hubble parameter, with Sandage and his camp advocating a relatively low value (in the 50 km/s/Mpc range), while deVaucouleurs and his partisans pushed for a higher value (100 km/s/Mpc or thereabouts). I find it amusing that the value established in part by the Hubble Space Telescope was roughly halfway between the earlier estimates, meaning both of them were wrong.

The gamma ray burst GRB 100621A, discovered in 2010. GRBs are some of the brightest objects in the entire Universe, outshining everything else put together during their brief periods of brightest activity. For many years, however, astronomers debated whether they were local objects in our galaxy, or very distant. The latter answer turned out to be correct, based on many years of hard work. [Credit:  NASA/Swift/Stefan Immler]
The gamma ray burst GRB 100621A, discovered in 2010. GRBs are some of the brightest objects in the entire Universe, outshining everything else put together during their brief periods of brightest activity. For many years, however, astronomers debated whether they were local objects in our galaxy, or very distant. The latter answer turned out to be correct, based on many years of hard work. [Credit: NASA/Swift/Stefan Immler]
For a long time, the debate was ascendent, but it seems pretty silly now—at least to me. Similarly, some of the other papers in the stack I got involved the debate over the nature of gamma ray bursts (GRBs), specifically whether they were local bright sources of gamma rays, or objects located much farther away in space. The consensus is strongly in favor of the latter: GRBs are some of the brightest objects in the Universe, corresponding to extraordinarily violent cosmic phenomena like collisions between neutron stars, or explosions of extremely massive stars. These debates only persisted as long as the data was incomplete or ambiguous; once the evidence strengthened, the issues that caused virtual hair-pulling and real conflict in the community more or less evaporated.

That’s not to say the issues weren’t real at the time. Science isn’t magical: new types of measurements may require many years of hard work to become accurate, and in some cases can require entirely new technology before they can be done properly. To measure the Hubble parameter, astronomers need to know distance and velocity accurately, and independently of each other. For best results, both of these measurements require knowledge of the intrinsic spectrum of an object (galaxy, supernova, or what have you). Additionally, galaxies are moving relative to cosmic expansion, due to gravitational interactions with each other; that needs to be corrected for to get an accurate number for the Hubble parameter. In other words, this stuff isn’t intrinsically easy to do.

However, any number of debates didn’t settle the matter. Today’s debates in cosmology are over the nature of dark matter, the substance of dark energy, and different models of inflation. Even though some of the debaters will be right and others wrong by necessity, it’s not the debate that will determine that—it’s the evidence. Some of these challenges are very difficult: inflation in particular is something we can only study indirectly, and particle colliders have ruled out many of the simplest options for the composition of dark matter. If the past is any guide, ingenuity and persistence will eventually pay off, perhaps in ways we don’t currently anticipate.

Of course, most scientists recognize and acknowledge all of this. However, even we tend to overemphasize the role of debate, centering conferences around it and playing it up for the public. (I’m not even going to get into the “debate” over Pluto‘s planetary status, which is mostly an embarrassment, with emotions overriding the scientific content.) I think it’s a human tendency: we love controversy, and love to argue. I’m no different, though I’m not as into it as some people I can think of, who really seem to thrive on conflict. Who doesn’t want to be right?

On the other hand, I won’t debate Creationists or climate-change deniers, even though the evidence is on my side. I’m not a good debater, and a skilled opponent could trash me. I’m aware of that fact, so I find it better to lay on the evidence in my writing and avoid direct confrontation. In fact, framing science as being about debates can make every issue seem equally important. After all, if there is legitimate conflict over the nature of dark matter and we debate about it publicly, maybe to the public there’s something to the “debate” over climate change—even though there isn’t. The jury has ruled on the Hubble parameter, evolution, climate change, and the origin of birds, all things that were debatable at one time, but are no longer controversial.

Returning to the Astrophysiological Journey: the fourth, fifth, and sixth items are also telling. Halton “Chip” Arp built his reputation around an excellent catalog of interacting galaxies, which helped astronomers characterize the role of mergers and collisions in galactic evolution. However, he staked that reputation on a misguided attempt to prove that the Big Bang didn’t happen, and that the apparent motion of distant objects (such as quasars) due to cosmic expansion was actually due to an intrinsic effect. There was no real debate on the subject, but many astronomers participated in a bit of a pile-on—understandably since Arp’s ideas were so blatantly incorrect. However, from the parody table of contents, it might even look like the Arp-vs.-nearly everyone else conflict was coequal to the real challenge of determining the Hubble parameter.

True debate is only possible when the evidence isn’t in, and only profitable when it spurs us toward innovation and the collection of better data. I think we would do well to remember that. If a jokey journal cover is what it takes to remind us, I say bravo.


10 responses to “Scientific Debates Are (Mostly) a Waste of Time”

  1. Scientific debates are not necessarily a waste of time, especially when it comes to getting the general public engaged with science and scientific ideas. For many people, these debates get the thinking process started, which is always a good thing. These subjects tend to be popular among audiences at astronomy club lectures and outreach events.

    The climate change issue is really scary because in the political world, among those who make policy, rejection of the idea that human activity is changing the climate is still considered a legitimate position. Even Hurricane Sandy didn’t seem to change that. We’re literally doing nothing while the planet burns.

  2. I think you underplay the importance of debates- not in the sense that they don’t ever “solve” a problem in and of themselves- but in that they 1) Give practicing scientists motivation to gather more evidence; 2) As you point out, spur the development of new technologies that *can* gather the required observations; 3) Establish, in the eyes of potential funders, the validity and need of the problem’s solution; 4) Provide excellent examples for people like you and me to talk about the process of doing science to the general public.

    I agree that focusing solely on “debates” is (mostly) a waste of time, and likely contributes to a wide lack of understanding that good science consists overwhelmingly of endless drudge work. However, I think that point 4 is perhaps the easiest to overlook in terms of importance, as it influences point 3, which is arguably the most important in terms of getting good science done.

  3. I think that often when you get to the point of a debate, the scientific process can break down, and things become more about politics than the actual evidence. Thinking of paleoecology, the classic “climate versus humans” debates about the cause of the Pleistocene megafaunal extinctions were really quite nasty, and I think held science up because people were afraid to wade into that nastiness. They also prevented real progress, because they just reinforced binary thinking. Ditto to the Younger Dryas comet impact theory. I’ve seen some terrible, terrible science being done because the proponents of the theory are convinced they are correct. I try to read Chamberlain’s Method of Multiple Working Hypotheses once a year to remind myself not to treat my hypotheses like favorite children.

  4. In all of these cases, new data settled the matter. However, that data was costly to acquire, in terms of both time and money: consider the effort it took to launch the Hubble Space Telescope, which settled the Sandage/Freedman (*) Hubble constant acrimony once and for all.

    I would argue—how meta— that it was the persistence of these oft-acrimonious, decades-long debates which motivated the large expenditures of resources required to produce the data which made the debates themselves look “silly” later on.

    And even with the 20/20 hindsight vision, you’ve failed to produce a good predictive model for resolving these debates in advance: the split-down-the-middle solution for the Hubble constant debate would not produce the correct answer for the Shapley-Curtis debate, or for the GRB debate, or for Pluto. In some of these cases, the split-down-the-middle parameter space wasn’t even clearly resolved at the time of the most vigorous discussion.

    And ultimately it is the public who decides what monies will be allotted to the sciences in any given era. So it’s back to the Wisdom of Crowds, and we astrophysicists and scientists aren’t even the relevant crowd. In hindsight it’s the debate, and the attendant publicity, that made our current data-driven “oh that’s so silly” hindsight possible.

    (*) Since Wendy Freedman led the charge from the high-H_o camp for the last three decades, and helped run the collaboration that finally settled it, I’m citing her, not de Vaucouleurs. Forgive me. But de Vaucoleuars has lots of stuff named after him already, and I’ll be damned if Freedman’s going to fall through History’s cracks.

    1. I’m certainly not saying the “split the difference” solution for the Hubble parameter could have been seen, and in fact over the decades (as another correspondent reminds me) Sandage’s value moved down quite a bit before resting at 55. My point is that the debate was publicly acrimonious and more about each party asserting their personal authority than science. Whether that was the driving factor for funding the Hubble Space Telescope, I’d be willing to entertain that option if you have evidence for it.

      My solution for reaching out to the public isn’t debate, which mischaracterizes the process of science, but rather education and constructive outreach. The point you make about Freedman actually supports a viewpoint that debates make it entirely about personality and who thumps their chests the loudest. deVaucouleurs hogged the spotlight, but there were other players, perhaps ultimately more important players. I’d love to see public understanding of science divorced from the myth of the Great Man, hard as that may be to establish. (*Ahem* Stephen Hawking *ahem*.)

      (I mentioned deVaucouleurs because he was the name on the Astrophysiological Journey article. My neglect of Wendy Freedman wasn’t out of malice, so I stand corrected!)

      1. Note on de Vaucouleurs understood and accepted. But note that Freedman herself is/was quite a renowned chest-beater—I’ve heard stories of her ordering postdocs to re-reduce HST data repeatedly when it yielded “too low” of a Hubble constant. Unlike Sandage, she would bow to inevitability and mounting evidence, but she kicked hard on the way down. And then she threw that fact in Sandage’s face in public.

        So is the argument specifically that *acrimonious* debate—debates driven by personalities—are counterproductive?

        I mean, I could certainly find evidence that the need to settle the Hubble constant once and for all was put forward to members of Congress as a plea by representatives of the greater astronomical community. I seem to recall the aperture of the primary mirror being part of the discussion—if it had gotten any smaller, they would not be able to accurately measure Cepheid light curves to sufficient distance. “Representatives of the greater astronomical community” is probably more in line with the way you would like to see scientific questions reaching the ears of elected officials and/or the public at large?

        I cannot prove that the acrimonious nature of the Hubble Constant debate contributed directly to that process. All I have there is anecdotal evidence: that as students, we relished every word of these horror stories about Sandage’s and Freedman’s behavior. The soap opera underscored the scientific importance of that single number in our minds, and probably made us prioritize it over other, equally-unknown, possibly equally-important values. Would the astronomical community have put it forward as one of the most-needed pieces of information without that cult of personality? Maybe. Quite possibly.

        But hell, it was fun to watch.

        In the case of Pluto, though, I think he debate did increase participation in the IAU vote which de-frocked our little Kuiper belt object. I heard rumors of fisticuffs in the halls at the IAU that year… but the vote was overwhelming, wasn’t it? If 150 Kuiper belt specialists had voted that way rather than most of the membership of the IAU in attendance, I think the public discussion would be different. And I think the large turn-out is in part due to the cult of personality that came to surround Mike Brown et al.

        Moreover, I think it’s a little inevitable. Scientists are human; so is the science-reading public. Many of us introverts, but some of us are extroverts, and quite a few of us are surprisingly good at kicking up a rumpus when it suits our purpose. I do see your argument that this sort of public train wreck teaches the wrong values about critical thinking and the scientific process— and I would argue that in an academic setting, it can create a toxic work environment that selects against introverted or simply more polite scientists who also have talent and vital contributions to make.

  5. Double thumbs up on: “My solution for reaching out to the public isn’t debate, which mischaracterizes the process of science”

  6. Hi there. Nice article. However, I think evidence is a function of time. What looks evident today may regarded silly in the future. I got the impression in your post, that you see evidence in inflation models and the like. I am not sure how evident something is which obviously does not have a scientific ground from a simple point of view: the possibility to falsify a hypotheses. The inflation model is not a theory because there is no real observational evidence so it is rather a hypothesis. Another point is that people are so sure that the space is expanding. As Dirac and Dicke showed there is a way to understand redshift as a change in the speed of light ‘crossing’ a gravitational potential. I am not sure that everything is so clear, evident, and obvious experts are telling us. In that sense debates among competitive alternatives are very important. That’s science!

    1. That is a completely misleading assessment of inflation. The evidence for inflation is indirect, but it’s also very good: the smoothness of the cosmic microwave background, the flatness of the Universe on the largest scales, and so forth. Data from the WMAP and Planck probes rule out a number of possible inflationary models as well, so it’s not true that inflation isn’t testable. Additionally, if large-scale gravitational wave observatories can be built, we’ll be able to observe inflationary signatures directly. There are some alternatives to inflation that are currently viable (and testable!), so inflation is certainly falsifiable.

      Similarly, the Dicke/Dirac model for variable speed of light is no longer a viable alternative, based on several decades of observations. It was a falsifiable proposition, and has been definitively falsified (along with “tired light” and “intrinsic redshift” models). I know some people keep dragging it out and presenting it as a legitimate concept, but you have to do a lot of violence on other theories to make it work.

      Evidence by itself needs to be interpreted, as you rightly point out. However, not all interpretations are created equal, and over time we refine our ways of thinking about them. Debate is not the proper way to go about that process.

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