In an effort to turn this blog into a pluralistic forum, you will on occasion see spotlighted contributions from individual commenters and excerpts of exchanges between readers. Over the weekend, the who started this ruckus post has triggered an interesting thread on, among other things, the value of citizen scientists. Part of the discussion has keyed on how to determine if citizens are engaging with climate science sincerely or as politically/ideologically motivated actors. Another strong theme of the thread, as Judith Curry observed, is the contentious issue of "trusted sources" for citizen climate scientists. I recognize this is a murky area to tread, which is why I thought that Jonathan Gilligan, an Associate Professor of Earth and Environmental Sciences at Vanderbilt University, helped shed some light with his contributions to the thread. (Gilligan is also the Associate Director of Research at the Vanderbilt Climate Change Research Network.) Below is one of his comments (slightly modified for new readers) that I thought deserved to be taken up more in full. From Jonathan Gilligan: I see two separate problems here: Establishing good faith and sincerity and establishing competence. Good faith: Too many scientists have been discouraged by seeing the same people repeat the same disingenuous objections, first to the CFC-ozone connection and later to AGW, long after the objection was debunked. People are much more likely to take the time and effort to engage in a dialog if they feel the other side is willing to listen with an open mind and consider that it might be wrong (this problem runs both ways in these controversies, but it would be a mistake to set the bar for open-mindedness by mainstream scientists so high as to require that they be prepared to jettison decades of solid empirical and theoretical work on the basis of a new revelation by someone with little track record; more on this below). One source of trouble is the tendency to stereotype or judge people by association: just because many people in the past have argued disingenuously about anthropogenic global warming (AGW) doesn't mean a new interlocutor with similar opinions will do so, but it's human nature to jump to that conclusion. The water is poisoned badly at this point, and there is a real need for some way that sincere people in the scientific community and the general public can demonstrate their good will to one another. The second problem is establishing competence. Scientists in certain fields regularly receive communications (often accompanied by lengthy diatribes) from sincere citizen-scientists purporting to refute special relativity, quantum complementarity, the second law of thermodynamics, and so forth. These days, proposals for carbon sequestration and clean energy are on the rise in my mailbox, including schemes to harvest unlimited free energy from magnetic monopoles or the quantum zero-point field. Sometimes it's easy to fire off a quick email pointing out the flaw in the argument, but sometimes the correspondent has a lengthy tract with lots of mathematics and it's not worth the hours it would take to find and explain the flaw. Amateurs can also provide genuine insight and even advances, but when the signal to noise ratio is very low, it doesn't pay off to sort through it all, hoping for a pony. One thing sociologists of science have identified that separates earnest but misguided outsiders from competent practitioners is tacit knowledge"”the unwritten practical good sense you pick up working side by side with a master. This is what graduate training or apprenticeships confer that simply reading books and journal papers cannot. People who lack appropriate tacit knowledge often can't figure out the context in which to put a single piece of research, the judgment to determine the quality of a new publication, and so forth. As Harry Collins and Robert Evans point out, "it can be shown that what is found in the literature, if read by someone with no contact with the core-groups of scientists who actually carry out the research in disputed areas, can give a false impression of the content of the science as well as the level of certainty. Many of the papers in the professional literature are never read so if one wants to gain something even approximating to a rough version of agreed scientific knowledge from published sources one has first to know what to read and what not to read; this requires social contact with the expert community." (Collins & Evans, infra, p. 22) A good example of this can be found in Thabo Mbeki's attempt to do a sort of citizen-science regarding AIDS by reading and assessing primary research literature on his own. His lack of tacit knowledge led Mbeki to seize on a few papers by outlier scientists, rejecting the connection between HIV and AIDS and judging that drug-safety testing showed that AZT was a poison rather than a useful antiretroviral drug, albeit with serious side effects. This confusion underlay Mbeki's decision not to provide AZT prophylaxis to babies born to HIV-positive mothers, a decision that cost tens of thousands of lives. Sociologist Harry Collins has conducted extensive empirical studies of scientific expertise and the acquisition and transmission of tacit knowledge. In his slim and very readable book with Robert Evans, Rethinking Expertise (U. Chicago, 2007, 160 pp.) he lays out a taxonomy of both expertise to use skills and expertise to judge others' expertise (what Collins and Evans call "meta-expertise"). The book is well worth reading for questions of how to figure out what makes someone an expert and different ways that people figure out how to establish someone else's degree of expertise. Two important things for this discussion are the observation that there are other ways to acquire the tacit knowledge necessary to understand complex technical science (Collins's prime example is gravitational wave physics) without actually being a practicing scientist and that even within the scientific community, scientists often lack the direct expertise to judge one another's competence, but use what the authors call "referred expertise" to judge scientists in other fields they are not themselves qualified to practice. Collins and Evans conclude with a discussion of how all this might apply to interactions between citizens and scientists regarding politically contentious issues, such as vaccine safety, genetically modified (GM) crops, and global warming. Collins and Evans hold out hope that members of the public can indeed acquire enough tacit knowledge through informal pathways (it would be very interesting to study how interactions on science blogs function at transmitting tacit knowledge from experts to layfolk) to understand and judge complex scientific questions, but that we should not romanticize this ability. Often (he offers the example of public rejection of mainstream scientific results on GM food safety) as a case where supporters of citizen science have judged that "the public "¦ are well informed about scientific advance and "¦ highly sophisticated in their thinking on the issues. "¦ [T]he public are ahead of many scientists and policy advisors in their instinctive feeling for a need to act in a precautionary way," when in fact the public are generally confused and misinformed about the science. Collins and Evans contrast this to the role of the ACT-UP citizen activist group in the 1980s at making sophisticated and useful contributions to the testing of early anti-HIV therapies. The way ACT-UP overcame Robert Gallo's initial dismissive treatment and won his attention and respect is perhaps a good positive example of how to proceed here (see also, S. Epstein, "The Construction of Lay Expertise: AIDS Activism and the Forging of Credibility in the Refort of Clinical Trials."20 Sci. Tech. Hum. Val., 408 (1995)). One problem with establishing competence is the asymmetry between experts and layfolks. We often use three attributes to judge expertise in others when we don't have time or expertise to go through their work in detail: credentials, experience, and track record. For judging mainstream scientists, we can use all three but for judging citizen scientists, credentials and experience are absent and it's hard to figure out what an amateur's track record is. If we believe in populist democratic governance, as opposed to rule by technocratic elites, better integration of citizens and scientists will be necessary. However, doing this is very difficult, and we should not oversimplify or romanticize the ability of outsiders to understand, judge, and contribute to research at the boundaries of knowledge.