In this ill-conceived thread, Scylla denies it has any value at all. That’s an issue worthy of debate, but let’s start over and debate it by itself, without the distraction of Rush Limbaugh.
I think I actually started a thread on this topic some time ago. Assuming I get home from work at a reasonable time tonight I’ll see if I can dig it up…I don’t remember whether there was much response to the thread or not.
As for the value…depends I suppose on what you are trying to achieve…and who exactly we are talking about as part of this ‘consensus’ of scientists. If we are talking about scientists in a very narrow, vertically defined field (say, geology, or physics), then a consensus should carry quite a bit of weight IMHO…though again IMHO that doesn’t necessarily mean that it should be cast in concrete and viewed as if the ‘debate is over’. If we are talking about a broad range of ‘scientists’ from myriad horizontally defined fields (say a physicist, geologist, paleontologist with a few medical research scientists and some other fields tossed in), then such a ‘consensus’ is less valuable…as really only the experts in the vertical fields that touch on the question are qualified to provide informed opinions on whatever topic we are talking about…the rest are just fluff. Intelligent and perhaps brilliant fluff, but fluff all the same, as they are most likely NOT experts on the question at hand.
Even in something like Evolution, refinements continue to happen…and the reason they do is because the debate ISN’T over, at least wrt all the data isn’t in, all the factors aren’t fully known. This is a good thing…it keeps things from stagnating, keeps things moving forward…keeps things from degenerating into dogma, handed down from on high. I know that in physics and cosmology there have been a LOT of sea changes in the last 20-30 years, overturning what was a ‘consensus among scientists’ several times, as theories are revised, updated…even tossed out with new ones to replace them. Thats what science is all about.
-XT
Speaking as a scientist, there are two ways to generate consensus.
- Putting forth a very compelling and iron clad case that no one can nitpick away.
This is no small feat. If you attend a journal club you will see a very good set of experiments that made it into a very good journal be picked apart to sometimes insane degrees. If you’re case makes it past that, and people are still nodding their heads, the consensus means a lot.
- Generating enough support from enough highly respected people that it would be career suicide to disagree.
Becoming a scientist is the longest, most precarious and most financially unrewarding career path there is. I’m pretty low on the totem pole right now. I find myself in meetings every week with people very senior to myself. If they have convinced themselves of something, it would be very difficult for me to vehemently disagree. I can certainly voice my opinion, and will certainly be heard. If my opinion is compelling, I can sway some favor. But, if minds are already set, I would have to back down, because I don’t have the capital.
I think science is a much more egalitarian system than nearly anything else, and most consensus probably falls into category one. But, I’m always on the lookout for category two.
Remember for every “scientist” who you hear about voicing his or her opinion, there are dozens of postdocs with PhDs and tons of experience who may disagree, but aren’t being heard.
But at what cost?
Like all Dopers, I find nitpicking distasteful. 
Found the old thread on this topic if you are interested BG: here
-XT
Consensus has a lot of value in science especially for non-scientists, because of the process involved. If an idea has a consensus, it means that people who generally really understand their subject have put it through the wringer, and it has come out strong nevertheless. While an idea that has gained a wide consensus (and especially if that idea has recently gained that consensus, rather than just being some very long unquestioned assumption) may not be right (as nothing in science is certain), but you can bet that what it has is a lot of very compelling evidence and reasons for thinking it correct that are a damn good justification until some better evidence comes along.
If you’re going for “theory”, you’re willing to put up with nitpicking. Every experimental system will have it’s weaknesses, and the nitpicking helps determine whehter you’ve rigged the system with your system, or whether what you are seeing is generalizable.
(Post modified from the other thread)
It was said that a Scientific consensus has no value in science.
I think that is hard to say that when one considers the alternative: truth by fiat, individual intuition, minority verdict, or non-expert verdict is many times more expensive or deadly, but I don’t think that is the value dissenters are talking about. 
Anyhow, in this case, as a result of what **jshore ** pointed out, minority opinions that are more logical and truthful than a consensus do not stay in the minority for long. As I notice so many times with extreme conservatives, time is once again the enemy of saying that there is no value in consensus for scientists.
For the consensus that we are talking about is from experts with now several decades or years of investigation. And that consensus is not discouraging dissent, as much as the minority is screaming about it, far from it.
For example, I do remember reading that researchers investigated if one predicted effect by one of the best dissenters was going to show in the form of more clouds in one of the atmospheric layers, when after several years the clouds failed to appear as predicted the dissenter just changed what could be expected, I think that many would not give that researcher even the time of day after that, but just because his new predictions are testable more research will be headed that way.
So scientific consensus is not a scientific argument, but the consensus can be based on the scientific method.
It’s probably useful to look at how consensus gets built. In my field (more engineering, but lots of professors involved) it goes something like this
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Someone writes a paper ahead of its time, which gets ignored
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Someone a few years later writes a similar paper, with better results, which is somewhat more useful or in the mainstream.
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In some cases everyone agrees, and write papers extending this first one. More frequently, lots of people think this concept is either wrong or trivial, and the problem is better solved by one of several other methods.
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As more research and experimentation is done, some of the opponents change their minds, more just drop the subject and pretend they never objected. If pressed they’ll admit it’s true, but no great advance.
At this point a consensus is reached. Up to now it was somewhat daring to agree, after this it is somewhat daring to disagree. If no senior scientists publish papers against the consensus in a year or so, it is pretty solid. If they do, it might collapse, if they have a valid point, since often problems with the consensus are buried in the rush to get on the bandwagon.
Nothing I do is as important as climate change. Consensus means that most of the valid opposition has dropped out or changed their minds. That’s significant. We’ll see if cracks appear. However, since it is so easy to backslide, it seems prudent to do something while we’re waiting to see if the consensus gets broken.
Of course, climate change is a special case because it’s not a purely intellectual question of interest only to specialists in the field. Economics and political ideology are bound up with it. Whether that makes the existing IPCC consensus on the pro side more or less credible is a debate in itself – but a fairly one-sided one. I hold it makes the consensus more credible, because corporations have invested so much time and money in attacking it and setting up “astroturf” climate-change-skeptic organizations and yet the consensus still stands.
Add, “…and some die.”
You write this statement as if the proponents of human caused Global Warming have not invested a lot of “time and money” in pushing their case.
It does not make the “case” for either group of advocates more or less convincing.
In the long run, people who have a blind faith in human caused global warming, a belief which resembles a cult rather than a proven and sound scientific finding, probably won’t matter. I don’t believe politicians in the advanced countries will take the kind of decisions made by economic imbeciles like the de facto caudillo of Venezuela.
Here’s an example or two of scientific consensus:
Example two.
Wegener on continental drift
Do you think scientists are any better today than they were then?
Bolding mercilessly mine.
Their advertising and PR agencies could not swing the masses
- ergo, move from the fox to the hounds (which you did not say)
Some things, in PR jargon, have ‘legs’ - I would rephrase it as ‘some things have populist appeal’
Noone is claiming that science is infallible. However, the question is what other choice do we have than to try to go with the best scientific knowledge that we have at the time. Or, do you want to just allow politics to trump science when your politics makes the science unpalatable to you?
Two other comments: (1) As that wikipedia argument on Wegener noted, Wegener’s hypothesis lacked a mechanism which is why it didn’t gain broad support in the scientific community. (2) The theory of anthropogenic global warming due to greenhouse gases is itself an example of a scientific hypothesis that took a long time to become accepted in the scientific community and did so only once the evidence became much much more overwhelming than it originally was. The first calculations of what could happen if carbon dioxide was doubled were done by Arrhenius around 1900 (and were based on some even earlier ideas). See here for an excellent account of the history of global warming.
It’s actually far from clear whether Semmelweis was arguing against any sort of consensus whatsoever. There were many, many views in circulation and peoples’ reasons - some irrational, some justified - for rejecting his case, either partially or in full, were correspondingly varied. Just because Semmelweis only convinced a few people doesn’t mean that everybody else agreed about very much at all.
Similar points can be made about Wegener.
Stories about individuals heroically defying an irrationally unified Scientific Establishment are usually just as simplistic and mythical as the notion that Science unambiguiously knows The Truth. The myths just play to different audiences.
Simplistic, yes. Mythical, No.
The careers of both Wegener and Semmelweis suffered. Semmelweis was the hardest hit, from a financial/reputation/career point of view.
An ounce of proof outweighs a ton of consensus.
From a debate viewpoint, stating the consensus can be seen as arguing from authority.
You have to ask?
More to the point, the scientists they funded could not come up with credible evidence against anthropogenic climate change no matter how much money was poured into the research – defining “credible” as “sufficient to persuade, or move to serious doubt, other specialists in the field.”
Oh, of course they have – but not nearly as much money, because their financial resources are inferior to the other side’s.
Yes, of course. For the same reason cinematographers are better now than they were in 1920 and engineers are better than they were in 1700 – techniques and knowledge base improve over time.