Sunday 17 July 2011

A consensus is not science ? Contrary !

Even though it’s such an easy topic, few things have been so poorly understood by laymen as the role of a consensus in science, leading to phrases like ‘a consensus is not science’.

This statement could not be any further from the truth.

But it takes some understanding of the philosophy of science to understand what is wrong with the statement. Many people seem convinced ‘consensus’ implies scientific proof is lacking. Before dealing with consensus, it’s important to understand what “scientific proof’ actually means. I’ve dealt with this issue in my post Loose thoughts on some frequent fallacies. It’s very important to understand the philosophical travesty the post tries to make clear : a ‘proof’ in the sense of an ’absolute truth until the end of time’ does not exist.

As odd as it may sound, the word proof only reflects the current state of knowledge, we are not able to prove anything. Even for theories we ‘absolutely know for sure’ they are real we don’t have any proof at all. Just assumptions (usually strengthened by conducting experiments). Take for instance the gravitation-theory. It’s merely an unproven theory !
Let’s ask a tricky question : how do you ‘prove’ gravity is not just a theory ? I’ll give you a hint : you can’t. Really, it’s impossible !

Sure, you can write down Newton’s law :
global warming consensus climate science fallacy

Does this law ‘prove’ gravitation ? No !

Sure every experiment you conduct will obey he law, but this doesn’t prove the equation. Not at all. It just doesn’t falsify the theory, that’s all. Conducting the experiment a zillion times does not provide any evidence or ‘proof’ next time the apple will fall from the tree too. After all, one day, who knows, the apple will not fall. The point is : science works with assumptions and predictions, but from a philosophical point of view none of these provide an absolute evidence or ‘proof’.

Nevertheless, no one in their rightful would discard gravitation. Why ? Scientific theories never ever are accepted because they are proven to be right (as we cannot proof them) but because scientists accept them. In other words, because there is a consensus.

Many people fail to understand this. While science accepts the evolution theory, there are people like Erich von Däniken saying extra-terrestrials came to earth and initiated earth’s civilisation. Why isn’t his theory accepted ? After all, we cannot prove aliens did not come to earth ? One reason is there’s a whole lot of positive assumptions supporting the evolution-theory, while there are none for the ET-theory. But as none of them really ‘prove’ anything, the simple reason evolution is accepted is a vast majority of scientists accepts the theory.

Science is –always– based on nothing more than consensus ! People who say a consensus isn’t science don’t understand science.


  1. A few years ago, I drew the distinction between live science and consensus science. The consensus is the body of well-supported things, which no longer had much if any discussion going on. The 'live science' is out on the edge where there's still active discussion in the field.

    The overwhelming majority of science sits in the consensus -- atoms do exist, gravity around earth is well-approximated by inverse square, there is a greenhouse effect, CO2 is a greenhouse gas, and so forth.

  2. Neil de Grasse Tyson summed this up with one of my favourite quotes " The laws of physics are real, everything else is politics.

  3. There is an important misunderstanding here that is perfectly brought out by the comment from Penguindreams. Says he: "The overwhelming majority of science sits in the consensus -- atoms do exist, gravity around earth is well-approximated by inverse square, there is a greenhouse effect, CO2 is a greenhouse gas, and so forth."

    This is confusing two totally different things: reality and consensus on what we know of reality. There is simply no connection. Atoms exist, AGW exists no matter what the consensus, no matter how advanced science is, et cetera.

    It is reality that forces a consensus with scientists. But this consensus remains so te speak a by product, a sort of collateral.

    I take issue with Jules' statement "Science is –always– based on nothing more than consensus!" because I think it is a dangerous oversimplification. The value of scientific consensus is given by the way it is arrived at. And it ain't by voting or decree.

    cRR Kampen (NL).

  4. Well, being a physicist, Eli would either roll a ball down a ramp or set up a torsion balance with two heavy balls.

  5. Dear Jules

    Consensus finding by itself is a scientific method, but it leads in my opinion to dictionary or reference discussions and not always to innovation for science itself.

    Usually scientific models and observations should be in reasonable agreement, i.e. there shouldn't be gross conflicts. As long as this is verified by many individual experimentalists and independent data, and if the model follows from a theory then it is all fine and nice. The mainstream in geophysical research is along these lines.

    But what we don't have is the absolute truth in scientific discussions. Absolute thinking is a bit like black white thinking, you don't find this in science, but you do find it in political and religious arenas.

    I once elaborated on some of these ideas on my blog, and all comments are welcomed:



  6. cRR, i've been away for a while, so hadn't had the chance to respond yet.

    i have some problems with your statement : "AGW exists no matter what the consensus"

    as my post tries to explain, you cannot say AGW exists (as philosophically speaking there's no such thing as a proof), you can only say there's a consensus amongst scientists the proof for AGW is sufficiënt...

  7. So now I've been away for a couple of weeks (Norway, where I found that a diversity of maps need to be redrawn where glaciers have disappeard or ice caps suddenly show nunataks)...

    I was unclear and should have said: 'the existence of AGW does not depend on consensus, but consensus may, or even should depend on existence of AGW'.

    Proof in the strictest sense exists only in mathematics (or rather logic). Aside these subjects, which have sometimes been called to be non-sciences, we can speak of 'proof beyond reasonable doubt'. In physics unreasonable doubt would lead people to try to fly or to walk through brick walls, a situation slightly different from disbelieving that Pi is an irrational number as such disbelief cannot be lived, but quite unlivable nevertheless. 'Proven beyond reasonable doubt is _more_ than consensus'.

  8. true, but even something proven 'reasonable doubt' is hard to prove ;-)