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The Importance of Consilience in Science

The Importance of Consilience in Science

Science is not a democracy. A consensus of evidence may be interesting, but technically it may not be significant. The thoughts of a majority of scientists doesn’t mean a hill of beans. It’s all about the evidence. The science is never settled.

These are refrains that I and other science communicators have been using over and over again when we turn to analysing debates and discussions based on scientific principles. I think we get torn between remaining true to the philosophical principles by which science is conducted and trying to make those principles familiar to an audience that probably does not understand them.

So let me introduce a concept that is all-too-often overlooked in science discussions, that can actually shed some light deep into the mechanisms of science and explain the anatomy of a scientific debate. It’s the phonically beautiful term ‘consilience’.

Consilience means to use several different lines of inquiry that converge on the same or similar conclusions. The more independent investigations you have that reach the same result, the more confidence you can have that the conclusion is correct. Moreover, if one independent investigation produces a result that is at odds with the consilience of several other investigations, that is an indication that the error is probably in the methods of the adherent investigation, not in the conclusions of the consilience.

Darwin_tree 250px(w)Let’s take an example to unpack this concept, an example where I first came across the term and it is a beautiful case of consilience at work. Charles Darwin’s On Origin Of Species is a masterpiece of consilience. Each chapter is a separate line of investigation and, within each chapter there are numerous examples, investigations and experiments that all join together to reach the same conclusion: that life changes through time and that life has evolved on Earth. Take apart On Origin Of Species case by case and no single piece of evidence that Darwin mustered conclusively demonstrates that evolution is true. But add those cases back together and the consilience is clear: evidence from artificial breeding, palaeontology, comparative morphology and a host of other independent lines of investigation combine to confirm the same inescapable conclusion.

That was 1859. Since then yet more investigations have been added to the consilience for evolution. What’s more, these investigations within the biological and geological sciences have been joined with others from physics and chemistry as well as completely new areas of science such as genetics, radiometric dating and molecular biology. Each independent line of investigation builds the consilience that the world and the universe are extremely old and that life has evolved through unfathomable durations of time here on our home planet.

So, when a new line of investigation comes along claiming evidence and conclusions contrary to evolution, how can that be accommodated within the consilience? How does it relate to so many independent strains conjoined by a similar conclusion at odds with the newcomer? Can one piece of evidence overthrow such a huge body of work?

Such is the thinking of those pesky creationists who regularly come up with “Ah-Ha!” and “Gotcha!” factoids that apparently overturn, not just evolution, but the whole consilience of science. Without exception, every single case that has been brought forward over the years does not hold up to scrutiny: the contrary result is in error and thus not really in conflict with the consilience. Depressingly, most of the ‘examples’ that the creationists put forward have been discredited time and time again but they are always willing to try their hand at foisting discredited material on a new, naive audience.

The same can be said of the Climate Change debate. While it has been pointed out many times that this is not an even debate and that the vast majority of climate scientists are in one camp (for example here and here) this by itself is not particularly helpful: science is not a democracy. But what has been underplayed is that the consilience of evidence for anthropogenic climate change is particularly strong. The IPCC reports are a consilience of hundreds of independent lines of evidence all converging on the same or similar conclusions. Supplement that body of work with complementary investigations outside the reports and the consilience builds; we have more confidence that their conclusions are correct. This is then magnified because of the consilience between the investigations within climate science research and the findings of the rest of science. They all point to the same conclusions about how the world works and the climate science is comfortably nested within all the other scientific disciplines.

William_Whewell 250px(w)While researching this article, I found out that the term ‘consilience’ and its basic principles were coined by the polymath William Whewell (1794-1866). He was a truly remarkable man partly because of the breadth of his work taking in philosophy, theology, physics, mineralogy, mathematics, poetry, astronomy, economics, mechanics and others. He also coined many other words besides ‘consilience’ that have entered the scientific and general lexicon. He came up with the word ‘scientist’ as well as ‘physicist’, ‘catastrophism’ and ‘uniformitarianism’ and went on to suggest to Michael Faraday words such as ‘ion’, ‘anode’, ‘cathode’ and ‘dielectric’. Among his many notable associations: while he was a don at Cambridge, he met a young student, Charles Darwin, and later recommended him for the position of secretary for the Geological Society of London. In honour of their enduring friendship, Darwin quoted Whewell on the frontispiece of On Origin Of Species:

“But with regard to the material world, we can at least go so far as this—we can perceive that events are brought about not by insulated interpositions of Divine power, exerted in each particular case, but by the establishment of general laws.”

And thus was born the origin of the great consilience of human endeavour that we call ‘science’.

By Paul Willis (@fossilcrox)

Feature image “Consiliance” generated by RiAus.
Body image 1 “Darwin tree” sourced from Wikimedia Commons and authored by Charles Darwin.
Body image 2 “PSM V07 D008 William Whewell” sourced from Wikimedia Commons.

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18 thoughts on “The Importance of Consilience in Science

  1. Often it is hard to get through to people. Many have fixed ideas and look for things that support those ideas while avoiding anything that contradicts them. Some people say science is just another faith thing, with its adherents also picking only those facts that support their ‘belief’.

    So how to get through to people? This article suggests ‘consillience’. Would the two middle syllables dominate? Is there a plainer word in use? Consensus is no good, even for consensus of evidence, because it sounds too democratic, and as the article points out, science is not democratic. The majority opinion can too easily be wrong, and so often has been.

    Is there a better word? I can’t think of one so will leave the question open.

  2. These are some interesting thoughts about the nature of evidence about which I both agree and disagree. I particularly agree with the point that science edges closer to truth when similar conclusions are reached by independent observations by different methods. But you overlook how in professional practice science advances in academia and government funded research when you say the opinions of a majority of scientists don’t amount to a hill of beans. Peer review is the norm for publishing and for awarding grant funding. The process of communicating science and composing compelling arguments that convince fellow scientists is at least as important as the data itself.

    • You’re right of course, Martin, I think the article makes that point – only badly.

      95% of scientists agreeing with something is not (necessarily the same thing) as 95% of peer reviewed papers agreeing on something.

      Scientists *can* act like sheep sometimes and accept the herd mentality but I think that’s less commonplace that it used to be.

      The problem, it seems to be, is that people can’t differentiate between a telegenic moron with an agenda and a qualified person… And usually side with the attractive idiot.

  3. Hi Paul
    Nice piece! And I hope in some ways one that will defuse arguments. It’s not all or nothing, it’s about the building of knowledge over time and by many people.
    And it’s great to see a fascinating person such as Whewell brought into conversations. He did not support Darwin’s evolution, but he (I think) predated Darwin in rethinking the place of wastage in nature, i.e. that not all seeds and so on come to fruition. He made this argument (anonymously, though people soon figured it out) as part of the extra terrestrial life debate going on in the 1850s. The standard view was that ETs must exist otherwise what were all those planets and stars doing out there (the waste of it all!). Whewell used science to make an argument against ETs (though his goals were more religious in nature). Michael Crowe has a fascinating section on Whewell’s role in one of the chapters of his second volume of The Extra Terrestrial Life Debate.

  4. “The thoughts of a majority of scientists doesn’t mean a hill of beans. It’s all about the evidence.” Well, that is nonsense unless you think scientists are idiots. Who sifts the evidence and interprets it? A measurement is empty of meaning until someone with expertise interprets it. If we limit ourselves to ‘scientists with appropriate expertise’ then if we have any confidence in the scientific method we would expect that the majority of these scientists will be able to sift the evidence and each will come to their own conclusion and if their expertise and ability mean anything the most common conclusion will be the most likely to approach the ‘truth’ (whatever that is) most closely. The problem with the article is that scientific consensus is not the same as political consensus, it is not reached through the same mechanisms, ideally, and should not be thought of in the same way. Scientific consensus is achieved by accumulation of evidence, intellectual argument, discussion, and testing of theory. Political consensus is a morass of opinion and compromise. Consiliance might be important, but consensus is not irrelevant.

    Further, this whole idea that “The thoughts of a majority of scientists doesn’t mean a hill of beans. It’s all about the evidence” plays _into_ the hands of the nutjobs. It is a small jump from that statement to arguing that your favorite crackpot is the only person out there who knows the truth, that there is some conspiracy of the majority and only some elite band of creative thinkers know the truth. I hear this all the time from climate change deniers. This is mitigated by the insistence on converging lines of evidence, and clearly what we need is consiliance and consensus.

    • Thanks for your thoughts but I think that you may be confusing consilience and consensus. Consensus is a raw majority of opinion and does not exclude collusion between contributers. Consilience is a bringing together of all lines of research conducted independently. Far from giving concessions to the nutjobs, consilience exposes them. Consensus only enflames them.

      Posted on behalf of Paul Willis

  5. Thanks Paul. Your piece sent me to the bookshelf to look for EO Wilson’s great work ‘Consilience’ and dust it off.

  6. The debate is in the process leading to confirm or deny a proposal. When the scientific method is applied properly, regardless of the discipline: biology, geology, physics or astronomy, it allows us to approach the factual reality. As for imagination and dreams, it’s definitely a great spring for fiction writers, and everyone agrees that what is produced is rather the world as we want it to be, not necessarily as it is.

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