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"97% of scientists agree that climate change is caused by humans - if 97% of scientists told you a plane was going to crash, would you get on it?"
Arguments about the existence of climate change aside - is there a logical fallacy of some sort being employed in the statement above?
We could quite reasonably say that there is a logical fallacy of "argument from authority". However, we should then also say that "argument from non-authority" is probably a much worse fallacy (assuming that something must be true because some minor celebrity having not a clue of the subject says it's true, which happens often enough).
And the logical fallacy doesn't make it wrong. It's not proven, but most things in life are not proven, and in the absence of proof we cope by using probabilities. If 97% of scientists agree on something that is within their area of expertise, then the probability that it is right is quite high.
If you insist to act only on things that are 100% proven, then consider that "climate change is not created by humans" is only supported by 3% of climate scientists, and therefore much less proven than the opposite statement.
97% of the papers taking a position. The amount of papers taking a position were much less than the total number of papers on the topic. See the question on skeptics for more. Just realized @Pont is pointing out a similar argument
Oct 24, 2014 at 17:23
Suppose that a person advises you to do something, such as accept some idea or other. Whether you should do it depends on whether the person in question can refute objections to the course of action he is advising.
The fact that somebody happens to have called the person in question a scientist doesn't change that.
Some people seem to think that it makes a difference, but it doesn't. Scientific knowledge is created by conjecture and criticism, see "Realism and the Aim of Science" Chapter I by Karl Popper.
The idea that you should drop your standards of criticism when somebody says the word "scientist" is anti-rational and anti-scientific. That is, adopting or advocating such an absence of standards is a threat to science and rationality.
To be fair, the question is obviously intended rhetorically and rhetoric is in part about persuading people to make leaps of faith. From that perspective, this argument is probably a good one -- but if you wanted to answer it with rhetoric of your own from an apparently more sceptical position:
is there a logical fallacy of some sort being employed in the statement above?
There might be if the point is to not get on the plane, because this would be a classic fallacious argument from authority:
Number 3 is the genuine non-sequitur but it rides a bit on 2 of course.
However, the statement isn't about the plane, and there are a number of other "bad faith" interpretations in the above critique making it an intentional misinterpretation ("playing semantics"). In other words, this argument is unlikely to be taken seriously by anyone.
A reasonable, literate, and disinterested observer would probably say what was really meant was (i.e., a "good faith" interpretation):
Aerospace engineers are recognized experts on planes. If 97% of aerospace engineers said not to get on a plane, you would not get on the plane. Climate scientists are the recognized experts on climate, so when 97% of them say something about the climate, why don't you believe them?
Fleshed out like this, though, we begin to see the outlines of the problem alanf identified, namely that this might be a dubious argument from authority. It might even be considered fallacious in the same sense as the first example here albeit in a more round about way. The expertise of the aerospace engineers is more certain because aerospace engineers design planes, whereas climate scientists do not design climates, they just analyse them. Because of this, aerospace engineers have much more experience with trial and error, etc., and if 97% of them said a plane was unsafe, they're probably right.
The analogy to climate and climate scientists is a bit weak; I would call it dubious and not fallacious. The point is still clear, so again, as rhetoric, this works, and it is hard to counter in that sense.
I do not see this way of presenting things as a logical fallacy. This short two sentence summary is not a formal proof, and it's not intended to be. It's intent is to get you to agree to one of the premises of a subsequent argument: that in cases where there is scientific consensus you can/should use that information in guiding your decisions.
That implication is not directly argued for or justified in any manner, and thus there are various ways to diffuse it; alanf has already presented one. Another would be that scientific consensus about climate change is a different beast than scientific consensus about whether a plane is flightworthy, and thus even if you accept the second sentence, it need not affect your thoughts w.r.t. climate change. You can also pick apart features of "which scientists" and "where did this 97% number come from" etc.
Merely presenting things in a manner that seems to lead to an obvious conclusion does not make the presentation fallacious.
This is the logical fallacy known as "recourse to authority". It says that you should believe something, not because the writer has presented any actual evidence to back it up, but simply because some expert says it is so.
If the expert believes that something is true because he has evidence to back up his assertion, then he should present the evidence. In that case you will be convinced by the evidence (assuming that the evidence is, in fact, convincing), and not by the fact that an expert said so.
If the expert does not have any evidence, then his opinion is no more well-informed than any random person's off the street.
Either way, you should be convinced by the evidence, not the fact that an expert said so.
In recent years I've heard some try to justify this sort of flawed argument by renaming the fallacy, "recourse to INAPPROPRIATE authority", and claiming that if the authority has the right credentials, that you should believe them. A little thought will show that this is a hollow distinction. OF COURSE anyone who says that you should believe something because an expert said so will claim that the expert's credentials make him authoritative. Who would say, "Bill Smith says that X is true. Of course Bill Smith knows absolutely nothing about the subject, but you should just believe him anyway." They're always going to say that Bill Smith is an expert on the subject. People who make this argument are trying to divert you into an argument about Bill Smith's credentials instead of the subject at hand. But even if Bill Smith has a master's degree in a relevant field and has worked in this field for 30 years, if he has no evidence to back up his claims and is just tossing out unsubstantiated opinion, what difference does his degree and experience make?
I'm not going to get into the debate about global warming per se here, that's a whole 'nother subject. But to embrace the analogy:
If someone told me that 97% of scientists say this plane is going to crash, I would likely ask who this person is who is telling me and who the 97% of scientists are.
How did he get this statistic? Did he really poll an unbiased collection of relevant scientists? It's quite possible that the statistic is from a biased poll, or that he just made it up. On controversial, politically charged subjects, that's not uncommon.
What is his definition of a "scientist"? Everyone with a PhD in science? But what would someone with a degree in biology or astronomy know about the reliability of an airplane? Their opinion is unlikely to be any more informed than any random person off the street. They're probably just repeating what they've heard from others.
Often when you hear statements that some large majority of experts agree that X, it turns out that they are defining X to only include people who agree with them. Like, "We asked the scientists who work for Foobar Airlines, and 97% of them agreed that planes from Whatsit Airlines are dangerous and will probably crash." Or, "We asked scientists who really know about the dangers of air travel -- that is, the scientists who are members of the Man Will Never Fly Society -- and 97% agreed, etc."
Experts are human beings, too. They can be biased by their political or social beliefs. A scientist who makes his living studying X is unlikely to say that X is totally bogus. And scientists who have no specific knowledge of the subject in question can fall into the "everybody knows that ..." trap just as easily as the general public.
For example, a number of years ago the president at the time called a conference of economists to evaluate his economic plan. And I saw many stories in the news about how all the economists who attended the conference agreed that the president's plan was basically a good idea, the only question was whether it went far enough. Well, duh. They said that like that proved something. But surely he didn't invite economists who he knew would say he was going in the wrong direction.
