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Posts Tagged ‘Consensus’

Picture credit: NOAA.

Picture credit: NOAA.

Note: I have joined the “virtual class” component of Dan Kahan‘s Science of Science Communication course at Yale University. As part of this I am endeavoring to write a response paper in reaction to each week’s set of readings. I will post these responses here on my blog – my paper for week 11 is below. Previous responses are here. I will also be participating in the discussion on Kahan’s own blog.


This week’s focus:

What is/should be the goal of climate science education at the high school or college level? Should it include “belief in” human caused climate change in addition to comprehension of the best available scientific evidence?

I started off thinking I had not changed my mind since writing my evolution education post two weeks ago. I planned to contend that, as with evolution, there is a reason that we are not satisfied for students to simply acquire knowledge about climate change. If they were to cogently describe what the theory of anthropogenic global warming (AGW) entails, but flat-out deny the truth of the theory, that would leave us unsatisfied – not just because global warming is a pressing issue which requires political will and thus voter backing to tackle (though that’s certainly true) but because we’d be left with the feeling that on some level the student still doesn’t “get it.”

Unpacking my argument from last week – which proposed that we should aim for students to believe the following…

(proposition p) Evolution, which says x, is the best supported scientific way of understanding the origins of various species, the way species adapt to their environment, etc etc.

… I can identify three reasons for this to be our aim:

  • First, because science *is* the best scientific explanation for these phenomena, and thus by knowing this, students know a true fact about the world;
  • Second, because armed with that knowledge, they are better equipped to apply the theory of evolution to scientific and other real-world problems; and
  • Third, (as I outlined in my comment to Cortlandt on the next post) because we wish students to understand the scientific justification for the theory of evolution, and if they understand that, then belief in proposition (p) necessarily follows. (It occurs to me now, however, that this is not the most terrific argument, because necessity does not flow in the other direction. Believing that p does not necessarily mean the student understands the scientific justification for evolutionary theory; he could take (p) on faith.)

The consensus problem

The climate equivalent of proposition (p) might be something like:

(q) The theory of anthropogenic climate change is the best scientific explanation we have for observed increases in the mean global temperature, and the theory predicts that if man continues to produce greenhouse gases at a similar rate, the temperature will continue to rise.

Proposition (p) could have included a stipulation about predictive power – indeed, to be a valid scientific theory, the theory of evolution must have predictive power. But while I didn’t think that needed to be spelled out for (p), I have done so for (q), because climate change is a subject whose vital importance – and whose controversy – truly rests on its predictions.

But there’s a problem here, and maybe a mismatch. In proposing that we aim for student belief in proposition (p), I figured we were disentangling identity from knowledge. Any student, taught well enough, could come to see that proposition (p) is true – and still choose not to believe in evolution, because their identity causes them to choose religious explanations over scientific ones.

For climate change, however, we may not get that far. There seems to be mixed evidence for the effectiveness of communicating scientific consensus on AGW.

As previously discussed, Lewandowsky et al found that subjects told about the 97 percent scientific consensus expressed a higher certainty that CO2 emissions cause climate change. Dan Kahan counters that this finding seems to bear little external validity, since these are not the results we’ve seen in the real world. From 2003 to 2013, the proportion of the US public who said human activities were the main cause of global warming declined from 61 to 57 percent.

In Cultural Cognition of Scientific Consensus, Kahan finds that ideology, ie “who people are,” drives perceptions of the climate change consensus. While 68% of egalitarian communitarians in the study said that most expert scientists agree that global warming is man-made, only 12% of hierarchical individualists said so.

2015-04-30_22-26-11

From Kahan, Jenkins-Smith and Braman, Cultural Cognition of Scientific Consensus. Journal of Risk Research, Vol. 14, pp. 147-74, 2011.

 

On the other hand, as Kahan said in a lecture at the University of Colorado last week (which I live-streamed here – unfortunately I don’t think they’ve posted the recording), most people who dismiss AGW nonetheless recognize that there is a scientific consensus on the issue. At least on the surface this seems at odds with Kahan’s previous findings, so I’d like to look further into these results. (I think the difference may come down to what Kahan describes, in Climate-Science Communication and the Measurement Problem, as the difference between questions that genuinely ask about what people know and those that trigger people to answer in a way that aligns with their identity. Why one of Kahan’s consensus questions fell in the former camp and one in the latter, I do not yet know.)

How is it possible that someone can recognize the scientific consensus on AGW, but still dismiss the truth of AGW? The most natural answer is that such people can readily dismiss the scientific consensus, perhaps arguing the scientists are biased and untrustworthy. This, by the way, points strongly that we should have always expected consensus messaging to fail!

 

So, if the aim is not consensus…?

Returning to education, I think this warning about consensus messaging points to the importance of creating a personal understanding of the science – i.e., exposing students to the reasoning and evidence behind climate change theory, and walking them through some of the discovery processes that scientists themselves have used. There may be serious limits to what this can achieve, because smart students may perceive that the arguments being used in the classroom have been developed by the scientists that they distrust. But undecided students may be persuaded by the fundamental soundness of the scientific arguments.

There is another danger: conservative students (especially the smart ones) may also reject the scientific arguments advanced in class because they will perceive that at a certain point they must taking things on authority; that the processes involved are too complex and the amount of data too large for a non-specialist to come to a solid independent judgment on. Furthermore, the students can entertain the idea that there is a viable alternative scientific theory because there are many prominent voices that back up this view.

 

Back to evolution

Again looking back at last week, I realize now that the same problem exists for evolution. The genius of “intelligent design” and “creation science” is that they allow an exit from the scientific-religious conflict in what many of us would call the wrong direction. Students can use this “out” to accept the science they like, reject that they don’t, and view it all as a “scientific theory.” Rather than accept (p) and then be forced to either choose religion over science, or somehow partition these parts of themselves (which Hermann, as well as Everhart, indicate is how many people cope), students may use religion *as* science and reject (p) altogether.

So now I’m beginning to doubt whether my aim in that essay really was achievable. It’s probably still a good idea to aim for beliefs of type (p), because this is a means of encouraging scientific literacy and nature of science understanding. But religious students with a good grasp of the nature of science will probably still find that “out” and will not agree with the evolution proposition. And other, less scientifically oriented students will simply say, “OK, this is the best science, but I trust religion over science.”

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Note: I have joined the “virtual class” component of Dan Kahan‘s Science of Science Communication course at Yale University. As part of this I am endeavoring to write a response paper in reaction to each week’s set of readings. I will post these responses here on my blog – my paper for week six is below. Previous responses are here.

I will also be participating in the discussion on Kahan’s own blog.


Graphic from home page of the Consensus Project, led by researcher John Cook. Skeptical Science Graphics (Skeptical Science) / CC BY 3.0

Since the publication of John Cook’s 2013 study confirming climate scientists’ 97 percent consensus on humans’ responsibility for climate change, many science communicators have vigorously argued the importance of “teaching the consensus.” On a common-sense level, teaching the consensus seems like an obviously good idea. If you tell someone that 97 percent of experts on a subject agree, how could he carry on maintaining the minority position?

But science communication isn’t that simple. It’s much more frustrating, and fascinating.

Evidence for “teaching the consensus”

From Lewandowsky et al, The pivotal role of perceived scientific consensus in acceptance of science, Nature Climate Change, Oct. 2012.

From Lewandowsky et al, The pivotal role of perceived scientific consensus in acceptance of science, Nature Climate Change, Oct. 2012.

Let’s have a brief look at some of the evidence for teaching the consensus – which is backed not just by common sense but by several studies. Stephan Lewandowsky, in particular, has been a strong proponent of this approach. In “The pivotal role of perceived scientific consensus in acceptance of science,” he and his colleagues found that subjects told about the 97 percent scientific consensus expressed a higher certainty that CO2 emissions cause climate change – 4.35 on a 5-point Likert scale, versus 3.96 for members of a control group not exposed to the consensus message.

In addition, the consensus message appeared to have effectively erased ideology’s influence on global warming opinions. Those exposed to the message had a high level of agreement that CO2 causes climate change, regardless of their free-market ideology; whereas in the control condition, free-market endorsement was associated with a marked decrease in acceptance of human-caused climate change (see chart above).

Meanwhile, back in the real world…

But Dan Kahan points out that these findings don’t seem borne out by real-world evidence. From 2003 to 2013, the proportion of the US public who said human activities were the main cause of global warming declined from 61 to 57 percent.

During this period researchers published at least six studies quantifying the consensus, and there were also several notable efforts to publicize the consensus, including:

  • prominent inclusion in Al Gore’s documentary film and book “The Inconvenient Truth”;
  • prominent inclusion in the $300 million social marketing campaign by Gore’s Alliance for Climate Protections;
  • over 6,000 references to “scientific consensus” and “global warming” or “climate change” in major news sources from 2005 to May 1, 2013.

What accounts for this discrepancy? According to Kahan, “The most straightforward explanation would be that the NCC [Lewandowsky] experiment was not externally valid—i.e., it did not realistically model the real-world dynamics of opinion-formation relevant to the climate change dispute.”

What should consensus publicity look like?

I think there’s another possible explanation: that Lewandowsky did realistically model the changes in opinion that might happen with a concerted and well designed consensus-publicity effort – but that from 2003 to 2013, we did not actually see such an effort.

Kahan implies that messaging during this period was widespread and well-funded. But was it as widespread as we would need such a campaign to be? And were the campaigns carried out in the best manner possible? For example, did the communicators use the best dissemination methods, the best language and the best graphical representations? Should they have targeted different populations with different, tailored messages?

I would like to see a more comprehensive analysis asking the questions:

  • What did communication of the climate change consensus from 2003 to 2013 consist of? and
  • Did it meet certain criteria that we should require of such a campaign?

Whether the actual consensus messaging carried out from 2003 to 2013 had the same characteristics that made Lewandowsky’s messaging effective, I could not say. But it certainly seems worth investigating what those characteristics might be. Of course, a prime concern is to discover if those characteristics include or depend on the artificial psychology lab environment – which would indicate that it is impossible to influence climate change opinions through consensus messaging in the real world.

An aside on sample size

I also note that Kahan doesn’t question the validity of Lewandowsky’s sampling. I can’t help wondering if Lewandowsky’s findings might not be, in some part, an artifact of small selection size.

The researchers compared a control group of 47 to a consensus condition group of 43. This means they were not literally testing the effect of consensus messaging on individual participants, but concluding that the difference in opinions between the two groups was due to the consensus messaging that one group received.

While this approach is advisable (a literal “before and after” set-up presents the problem of demand effect, as our class saw in its examination of Ranney et al,) it also depends on a large enough sample size to minimize the possibility that uncontrolled and unseen variables are affecting results. I’m not convinced that Lewandowsky’s sample size was large enough for that.

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