What does consensus in the scientific community really mean?

And how is the layman to judge? This is with reguards to several debates I’ve seen in GD from time to time, many of them revolving around Global Warming/ anthropogenic warming or Evolution, but not exclusive to it.

Basically my question is, what exactly does it mean if there is a general consensus in the ‘scientific community’ about a specific issue? Many times people (mostly NOT scientists) use this as a club to signify that anyone disagreeing with the vast scientific community is an idiot…or deluded. Yet theories DO change…and sometimes radically. Thats the beauty of science…its constantly refining and challenging itself, coming up with new and better (or worse in some cases) theories that are then challenged.

What sparked this question was a show on the Science Channel a few nights ago talking about parallel universes and String Theory vs Super Gravity. It seems that in the 80’s and 90’s String Theory became THE widely accepted theory in the physics community, supplanting both earlier theories AND contending theories (like Super Gravity). I don’t pretend to have but a tenuous grasp of EITHER theory, but what struck me was some comments by one of the few scientists (who’s name unfortunately escapes me atm) who stuck to Super Gravity who was relating stories of how he was unable to attract either funding or graduate students to his cause, the antipathy and even hostility he received from ‘the scientific community’, etc. Because the Super Gravity theory wasn’t widely accepted it languished, with few proponents and a lack of funding…while String Theory, being widely accepted got all the funding (and publicity) it needed.

And if I understand correctly (a dubious proposition I admit), it was all over (to me) a very minor difference…namely (according to the show) String Theory supposed there were 10 dimensions while Super Gravity supposed/proposed 11. I’m sure there were others, but this seemed to be the key difference (gods know why).

As it turned out, after over a decade of sitting in the backwater, Super Gravity turns out to have been right (I suppose…at least the 11 dimension thing seems to have turned out to be key after all), and has been incorporated into M-Theory (again, all this according to the show).

How are laymen, not versed in all the in’s and out’s of the more esoteric and convoluted theories to judge? After all, it seems the pet theory, the one widely accepted, will get large amounts of funding, and all the personnel requirements it needs…while other theories, perhaps not as widely accepted, won’t. This may be a good thing or a bad thing…but how is one to judge if one isn’t directly and intimately involved?

Should we simply await developments or should we blindly trust the judgement of the scientists involved? How much of a club is it when a layman uses scientific consensus about a theory as a silver bullet to beat down disagreements in a debate?


Science, obviously, has as many bloody fights as the SDMB.

Despite String Theory winning a few battles, early on, String Theory was never recognized as having a consensus. Unfortunately, the only way to know this is to read enough to see the disputes. “Popular” periodicals of science are usually an OK place to find this information. While they may champion one cause or another (either following the crowd or trying to stake out an opposition perspective), the reputable one will always acknowledge the conflict.

For example, the neo-Darwinian Theory of Evolution, employing Natural Selection based on random variations has consensus. There is no reputable worker in the field of biological sciences who has proposed any serious challenge in many decades.

Within that umbrella of Evolution, there are any number of fights regarding smaller issues. Eldridge and Gould’s Punctuated Equilibrium has a strong following, but Dawkins and others oppose their hypothesis on the grounds that it denies gradualism or provides no useful observations.
Any serious reading of the literature should provide ample evidence that Punctuated Equilibrium has not achieved the level of consensus.

Eventually, one must read enough of Science, Scientific American, Science News, or even Discover or similar magazines to know where the consensus lies.

Consensus is achieved when scientists have collected and examined data independently and arrived at the same conclusions. Many independent groups are discovering things that all support the same general hypothesis. Of course bad science gets published, but the scientific process works well enough that when many different groups are seeing the same patterns, one should take notice, even if he or she is not an expert.

String Theory is not widely accepted. It does not affect the majority of physicists at all, so most of them have not even thought about it. Among physicists that have thought about it, there are many dissenters. One common complaint is that string theory makes no testable predictions (and therefore should not even be called a “theory”—it’s more like a conjecture). Another is that it allows for so many possible universes that it is not useful as a description of our universe. So there is currently not consensus on string theory, despite what that program might have said.

Technically, consensus means nothing: science works off proof. Do this then thathappens. Politically, as you’ve shown, it means everything; it just shows that scientists are as gullible as everyone else: it’s the herd instinct.

There is no question that scientist are susceptible to the same social dynamics as other persons. However, unless you can demonstrate a claim (by scientists in a relevant field) of consensus where there was not, in fact, consensus, your claim is not really relevant to the discussion.

There are cases in which scientists have arrived at consensus (subject to new information overthrowing the premises on which that consensus is based) and understanding what that means in terms of the real world would seem to be the topic under discussion. The typical lay person has little access to “proof” (if science actually engaged in “proof”) when it involves fairly arcane studies. This means that the lay person must rely on some sort of translation to arrive at an understanding of what, where, and when “science” makes a declaration. In common shorthand, that would be “scientific consensus.”

No, science does not work off proof. Science works off hypotheses that have good predictive ability and which have not been falsified - a quite different thing.

The danger of reading a bit of the popular press is that when a reporter talks to the proponent of one side, or that proponent writes an aritcle, it might sound like the issue is settled. You really need to count the number of papers on one side or another over time. I suspect there aren’t a lot of papers on Steady State coming out any more, so there is a consensus on the Big Bang.

You also have to carefully read the nuances of the writings of the scientists. Not even the biggest supporters of String Theory say it is settled. They may be optimistic, but that is different.

You need to be careful about considering the number of people working in an area. There is a herd instinct, in that many apply for grants for the latest hot topic, where they think the funding is. A lot of people just don’t have the oomph to fight to get money to work on something risky.

I think the problem you may have with “consensus” in this instance is the alleged customary reliance upon mounting experimental evidence supporting a particular hypothesis or theory. Of course, when you look at the attitudes of individual scientists, or even of groups of scientists during the formative years of a well-accepted theory, the details can get pretty messy, and human frailties only too evident.

In the case of quantum-gravity- and GUT-related research, it’s widely recognized that unless the universe we inhabit is very different than how it appears, the energies required to produce the predicted and unequivocal experimental signatures of relevant theories are so far beyond our capabilities, it’s not absurd to imagine we might never see the evidence.

Presently we’ve got two cornerstones of modern physics: General Relativity, and the Standard Model, a quantum field theory of the color and electroweak forces. Not a single experiment or observation has been able to convincingly refute either theory, and yet it’s known with certainty that neither one can be used to fully describe the physics of extreme energy densities, like in the centers of black holes, or the earliest epochs of the Big Bang. Straightforward attempts to combine the two yield meaningless predictions when one attempts to use them to calculate anything that can’t already be predicted just as well with GR. From these attempts theorists have gotten tantalizing mathematical clues they feel tell them it’s possible. They also have the example of electroweak unification, which is a highly mathematical model of a spontaneously broken kind of symmetry which simply cannot be expressed adequately with words. Beautiful mathematical structures and symmetries have cropped up in other places, revealed in the equations of relativity that show precisely why energy is conserved, and so forth. When Paul Dirac wrote down his famous equation, the best first attempt to unify quantum mechanics with Special Relativity, he doubted the result: That electrons have a positive counterpart. Realizing later he’d discovered the positron in an equation, he remarked that the equation was smarter than he was.

I think these sorts of developments marked the beginning of a approach to theoretical physics where rather esoterically aesthetic principles like “beauty” and “symmetry” became trusted as evidence of veracity. So many times have these stunning mathematical relationships and structures been as verifiable as they were compelling, there seems little reason to doubt that a skilled theorist can derive valuable clues about the promise of theory just by how beautiful the theory is.

Except when someone in the minority says the theory is not beautiful, and they propose an alternative which they think is beautiful, even while others think it’s hideous. What then? What then appears to be, in the absense of experimental evidence, a heated philosophical battle about how science ought to be conducted, and what constitutes proof. In the past, at least we like to imagine, one could settle such disputes by subjecting theory to the harsh challenge of physical reality. Only the strong survive, beautiful or not. For the nearly half-century that quantum gravity (and the latter half of that period was dominated by stringy theories), no such settlement could be had. An entirely different approach has been taken, and whether or not this approach has been a success or a huge waste of time no one really knows.

The “scientific consensus” is traditionally an opinion supported by a lot of factual information, and it’s historically been the case (as long as something like the commonly-recognized “scientific method” has been utilized) that consensus was arrived at through the evidential erosion of contrary positions. Not so anymore, depending on how you define “evidence”. I personally think the rather difficult nature of this debate is forcing the issue of not only the definition of a scientific consensus, but science itself. Maybe in a few years some big particle accelerators or space telescopes will change the landscape (if you will), but there’s no consensus on that.

"Consensus" means they don’t really know.

Read Karl Popper.

Link that should have been added to my previous post.

“‘Consensus’ means they don’t really know.”

That’s misleading, and characterizing science as the measure of a distance is rather limiting. Besides, the sun isn’t 93M miles from earth. The earth’s orbit is an elipse, not a circle, and therefore the distance isn’t fixed. Furthermore, e=mc^2 will probably be shown to be insuficient at some time in the future (if we neglect that fact that even that equation is true only under certain circumstances).

There are plenty of folks with “PhD” after their names who think ID is needed in addition to The Modern Synthesis to describe the evolution of life on earth. That doesn’t make the Modern Synthesis any less “true” than Einstein’s theories.

There are still credentialed holdouts in the world of Anthropology who don’t accept the Out of Africa theory of human evolution. But that is the consensus view, since it’s the view held by the overwhelming majority of scientists working in that field.

But we needn’t insist that there is always a consensus view. In some cases the field may be equally split or at least nearly so. There are always going to be cases where it’s a judgement call to say whether “X” is the consensus view or not, but in many cases we can be as sure as we need to be. I’d offer the Out of Aftica theory as an example of that situation-- I’m sure even Milford Wolpoff would agree that his Regional Contintuity hypothesis is not the consensus view.

This doesn’t make much sense. A consensus position could be accurate or not. That’s true of any opinion. The fact that one or many hold a particular opinion does not in any way automatically invalidate it. It’s true that the majority could be wrong to some degree, but they could just as easily be as correct as it is within human power to demonstrate. As far as Crichton is concerned, it’s worth considering he has his own peculiar axe to grind on the subject of anthropogenic global warming, and it’s arguably good for his book sales to offer his own polemic on related matters. If the consensus is “theory A, which has survived every single test we’ve ever subjected it to, is a darn good theory”, I see nothing “pernicious” about that.

“It’s only a theory.”

“It’s never been proven.”

“Scientists don’t even agree.”

It’s a very familiar set of arguments.

It almost always includes an alternative assertion that has certain characteristics.

It isn’t a theory

It cannot be disproved.

Scientists haven’t been studying it during the last few decades.

Mostly, these arguments are political, or theological. When drawn into them, don’t expect to win with evidence.


Tris: I don’t think that’s the main point that **XT **is driving at. It’s common in debates in this forum for people to talk about about consensus view of particular areas of scientific inquiry. I think he’s asked a very interesting question, and I’m not sure what the consensus view of the scientific community would be in giving an answer. :slight_smile:

The truth is not a popularity contest. I’d also watch out for how the consensus is defined. A Ph.D in the sciences does not mean that you are qualified to deliver an informed opinion on subjects outside your field of expertise.

You are probably right, and my response shows how terribly jaded my experiences have made me. The only arguments on science I have now days are with Creationists, and folks who think Global Warming is “Just a theory” made up by those darned scientists, to take away my Hummer!


Sorry to have missed the point.

The struggle for funding is the root of “Show business science” and it really strongly affects how the average non scientist perceives the edges of our understanding. One of the best observations on the realities of science and money was made by a “consultant” for one of the big production movies about Ebola. He said the movie cost more than the entire US Budget for all viral research for several years.

The thing I most enjoy reading in the quality science press is the continual argument about the details of data, and the implications of miniscule differences in that data. Even historically, that is the case. Kepler’s struggles with the data Brahe gave him for the orbit of Mars arose out of a set of discrepancies less in magnitude than the width of the index sight of Brahe’s instrument. Yet that small difference led to the Laws of Motion.

Science is always a process, and like any other human activity, it has its failures. Self correction is perceived as scientists not being sure. What is, in fact the greatest strength of this method makes it seem to some as a constant stream of failures.


Right. Consensus means a consensus of those well versed in the field. The views of hydraulics engineers on geology of medical doctors on climatology must be viewed with skepticism. Perhaps the public has been trained by entertainment to think of a scientist as an expert on everything - look at the Professor in Gilligan’s Island.

When Crichton says that all it takes for one person to be right, he’s correct. But we don’t know if this person is right until there is a consensus, do we?

I’d like to recast the question:

As a member of the public at large, non-expert about most things, how do I use “expert opinion” to formulate my opinions about areas outside my usual knowledge base?

Do I try to evaluate all the original data for myself and become an expert on everything (or foolishly delude myself that I am)?

Do I rely on accepting conclusions that fit my purposes?

Do I accept information from experts as likely true only when there is no dissent among any scientist at all, even if they are a severely minority view among the scientific community?

Or do I rely on the fact that the overwhelming vast majority of experts in the field believe a conclusion is valid?

And if the last then how is a member of the general public supposed to tell the “other side” which has no serious credibility but are only corporate hacks, from the serious minority POV dissenters? How are they supposed to tell the fad of the popular press from the real scientific consensus (short of reading real science rags with regularity)?

I think the short answer is “you really can’t”. The longer answer is the “consensus position” can be, and often has been, completely wrong. I think there is no solution to that conundrum except a degree of resignation about the main difficulty you alluded to: It would take a thousand lives, even if one had the necessary intellect, to gain the expertise required to competently evaluate even the relatively short list of current hot-button issues in science, and weigh in with a fully-informed opinion of one’s own. We either remain hyper-skeptical about everything except the smidgen of understanding we as individuals can acheive, or we put a measure of provisional trust in “the experts” and hope like Hell they’re not all full of baloney.

That is why it is important to get the view of the peer-reviewed scientific community in the field in question…and why it is important to listen to institutions like the National Academy of Sciences whose role is to present what the current view of the scientific community is.

I think DSeid’s point is the really crucial one. Basically, when science is needed to inform policy decisions, what is the alternative to getting the consensus of the scientific community? While it is true that there is no absolute guarantee that this consensus is right, I don’t really see any compelling alternative method that is more likely to arrive at the truth. And, the alternative that does seem to be implicitly endorsed, e.g., by those in the debate over climate change, is that one accepts the scientific consensus when it works well with one’s preconceived political or religious beliefs or economic interests and one doesn’t…and trots out the few scientists who disagree with the consensus…when it doesn’t. This sort of philosophy will push us back into the Dark Ages.