Dialogues concerning Natural Politics: Book Two
What is the significance of science and expertise for policymaking?
Book Two Synopsis: The main topic discussed in Book Two is the significance of science and expertise for policymaking. The purpose of policy experts is to compensate for the relevant ignorance of policymakers, who would otherwise lack some of the knowledge required to effectively perform many of their policymaking duties. The characters consider whether experts can satisfy this purpose generally or only under special conditions. The characters discuss the various methods by which scientific consensuses form and the significance of a particular consensus’s method of formation for its value as a policymaking tool. The characters also address the meaning for policymaking of science’s tentative nature.
Dramatis Personae
Emma – 30 years old; Fifth-year philosophy PhD student, specializing in political philosophy and epistemology; ABD (“all-but-dissertation”); dating Andre
Andre – 35 years old; Fourth-year philosophy PhD student, specializing in philosophy of science; Academic Advisor to undergraduate students in the Philosophy Department; dating Emma
Connor – 24 years old; Second-year philosophy PhD student, specializing in normative ethics; a devout political progressive
Jack – 25 years old; Second-year philosophy PhD student, specializing in logic and epistemology; a devout political libertarian
Book Two
Jack: Of course, the eugenic consensus was overturned in favor of the anti-eugenic consensus, as tends to happen in science, but that is exactly why our objections should worry you.
Andre: Exactly. Unless you believe that science has achieved something approaching infallibility, it is entirely possible that the seemingly benign, if not apparently beneficial, implications of some scientific consensus will lead you, just as the Nazis and other eugenicist progressives were led, to support policies and programs that will be considered repugnant when the relevant consensus is overturned.
Jack and Andre [together]: …as tends to happen in science.
Emma: Connie, let me ask, why science? Why should science guide policy?
Connor: What else you got? Divine revelation?
Emma: That’s a strange answer for a normative ethicist! The only possible bases of rational political decision-making are either revealed religion or empirical science? What about ethical norms? What about our commonly- if not unanimously-held conceptions of ethical interpersonal behavior? Our broadly shared notions of what we owe to and how to treat each other? Our moral beliefs have nothing to do with the legitimacy of different policies? This is entirely a function of their scientific adequacy?
Connor: It’s not that science should decide policy. The general will – or, at least, a majority of the electorate, preferably, of an expanded electorate – should decide policy. Science just helps design policies that conform to the requirements of the general will.
Emma: But, what if the experts and the voters disagree about the significance of some end?
Connor: Like I said, the voters should choose ends; they should be entirely sovereign in this regard.
Emma: That majoritarian democracy ensures popular sovereignty would seem dubious, given everything that Andre and Jack just argued. But, even granting that a simple majority guarantees the sovereignty of the people, ensuring that policy experts conform to all and only the decisions of the majority would seem easier said than done.
Connor: How so?
Emma: Consider two scenarios. In the first, voters choose an end that the scientific experts deem not just inessential, but counterproductive. Should the experts earnestly pursue this end? Should they try to realize an end that they believe to be against society’s interests? Are they, in any case, very likely to work hard to realize such a goal simply because of its democratic provenance, given their studied opposition to it? In the second scenario, voters fail to choose an end that the experts believe necessary to preserve society. Should the experts ignore this seemingly society-sustaining goal in favor of whatever – from the experts’ perspectives – potentially damaging rubbish voters happened to support in the moment? Again, are the experts likely to follow the democratic decision with any conviction?
Connor: I don’t know, frankly. Those are hard questions. I don’t have ready answers.
Emma: I envision a world of government-by-expert that is democratic only to the extent voters choose ends that happen to coincide with the preferences of experts, but where voters’ preferences are otherwise routinely ignored.
Connor: I see the point.
Andre: How often, or how generally, can we rely on science and what can we say about the quality of policy decisions made using science as a tool? Given what you just said, I presume that the relevant criterion is something like the effectiveness of policies – the extent to which they realize the democratically-determined goal, probably, I would imagine, without greatly exceeding the proposed costs – rather than their moral goodness, prudence, or what have you.
Connor: Yeah, right. It’s the electorate’s responsibility to ensure that the goals they choose are moral, prudent, pragmatic, and economical. Scientists just provide technical advice about realizing the goals decided upon by the electorate.
Andre: OK, so let me ask, which sciences are relevant for policymaking?
Connor: All of them, I would think, for one policy purpose or another.
Andre: Physics?
Connor: Surely, if you want to shoot a rocket into space…
Andre: Biology?
Connor: Of course, if you want to grow abundant crops and raise healthy pasture animals…
Jack: What about if you want to create a genetically pure populace, is biology relevant there, too?
Andre: Shush, you’re not helping.
Jack: I’m not trying to help.
Andre: What about ecology or environmental science, Connie?
Connor: Sure, if you want to avoid destroying the environment.
Jack: Economics?
Connor [laughing]: Economics is not a science.
Emma: Why do you say that?
Connor: Economists don’t falsify.
Jack: Of course they do! If economists didn’t falsify, we’d still be mercantilists and Soviet communism would never have died.
Emma: Those can’t both be true…
Jack: You know what I mean. Economists falsify, Connor. You just don’t like what they’ve falsified…because you’re a commie.
Connor: Wait, I thought I was supposed to be a Nazi. Now I’m a commie too?
Andre: Ignore him.
Jack: Yeah, ignore me…you commie.
Andre: I don’t see why falsifying – or not – is all that important.
Connor: Economists don’t agree on anything! They never achieve consensus. Look at how they reacted to the financial crisis: “The bankers did it!” “No, the government did it!” “Stimulate the economy this much!” “No, stimulate the economy that much!” “Don’t stimulate the economy at all!” Who knows the truth about economics?
Andre: I think there’s probably more agreement among economists than you realize. All economists agree that, whatever else might affect it, incentives are important determinants of human behavior. All economists agree, for example, that demand curves slope downward from left to right or, in concrete terms, that more of a good will be demanded as its price falls, other things equal. There might be some disagreement among economists about the specific goods or markets to which supply-and-demand analysis applies, and it is rarely a simple thing to know the slopes of the curves, which is to say, the elasticities of supply and demand, in particular contexts, but all economists agree about the basic dynamics of supply and demand. There’s a lot more agreement on theoretical matters than you’re admitting. Indeed, this theoretical agreement leads to considerable, if not complete, agreement among economists about more substantive policy matters. Most economists since Adam Smith have supported free trade. You will not find many economists supporting minimum-wage laws, rent control, or other types of price controls.
Connor: Economists don’t care about normal people. They don’t care about the working class. The economy can be run democratically to meet the needs of regular people. There’s no need for economists. They’re just apologists for capitalism anyway.
Jack: Oh, so they do agree about the most important thing!
Andre: It can’t be both, Connor. You can’t say economics is not a science both because economists don’t agree on anything and because they all agree about the benefits of capitalism.
Connor: OK, then I take back the former assertion and rest my case on the latter claim.
Andre: That’s not going to help you. First, it is simply untrue that all economists are apologists for capitalism. There are many heterodox schools in economics, several of which are resolutely anti-capitalist. Second, to the extent that there is agreement among economists about the benefits of capitalism, you have given no reason to think this agreement is not well-founded. You have given no reason to think that the economic policies of the progressive state should not be based on the widespread, if not unanimous, agreement among mainstream economists on the benefits of markets. But, more to the point, I think you have to consider a problem converse to the one you attribute to economics.
Connor: What do you mean?
Andre: I suspect that disagreement is more widespread, consensus less pervasive, in some of the sciences you named as crucial policy instruments than you seem to realize. I have had the distinct displeasure of hanging out with a number of professional physicists over the years and they don’t seem to agree about much, except, perhaps, that, on earth, objects tend to fall downward. Similarly, there is a consensus in biology in favor of Darwin, of course, but, as far as I understand the situation, the details of competing evolutionary accounts vary. You’re apparently fetishizing consensus as the criterion of both legitimate science and its proper use for policy purposes, but scientific consensuses are not always easy to come by and, as we have already said, tend to be non-permanent, at best, and ephemeral, at worst. What would you have politicians do when there is no consensus or when there are competing consensuses between rival schools of thought in some science that they need to rely upon as a policy instrument?
Connor: I understand what you’re getting at, the tentativeness of science and all that, but I don’t think a complete absence of consensus or cases of competing consensuses are very likely or, in the event, all that problematic.
Andre: But, you’ve just claimed that economics – the acknowledged “queen of the social sciences” – is insufficiently scientific for its analyses to figure in policymaking, because of its alleged failure to reach consensus. So, on your own account, some disciplines regularly fail to achieve consensus, problematizing their use for policy purposes. If not economics, what about sociology, a squishy science if there ever was one? You’re not really going to reject economics for policymaking purposes, but accept sociology?
Connor: I wasn’t planning on it…
Andre: What about political science? Granting everything else that you want, surely you need political science or something quite like it.
Connor: I don’t see why that should be the case. Politicians typically don’t make laws about political procedures. They don’t write – or re-write – political constitutions. What do they need political science for?
Andre: They might write constitutions. Everything we have said so far is applicable to the authors of constitutions as well as to legislators operating under an existing constitutional framework. But, that’s not my point. Would you like your favorite policies to be implemented and administered properly and to ultimately realize the goals they are meant to realize?
Connor: Of course.
Andre: Do you think knowledge concerning effective means of policy implementation and administration is innate or otherwise self-evident, or a priori, to policymakers?
Connor: Of course not.
Andre: Then your policymakers will need political science or something like it, a science of policy implementation and administration. Even the best designed policy, which I take to be the business of scientific experts in your system, can fail to achieve its goals because of improper implementation or maladministration. I mean, [in mock English accent] “there's many a slip 'twixt the cup and the lip,” you know?
Connor: I suppose.
Andre: So, good policymaking, on your account, requires that a univocal consensus obtains in all relevant physical and social disciplines that are, according to criteria you’ve yet to provide, legitimately scientific. What, I wonder, are you planning to replace economics with in policymakers’ schemes, since you deny it the status of a science? Economic phenomena are surely relevant to designing effective policies, yet you’ve just denied that we possess an adequate theoretical understanding of these phenomena. How then are policymakers going to control these phenomena well enough to ensure the success of their policies? What is going to fill the gap left by your denial of scientific status to economics?
Connor: Ideally, a better, more scientifically respectable, economics.
Andre: One that produces consensuses about policy-relevant economic phenomena…
Connor: Right, ideally.
Jack: But not about the benefits of capitalism over other political-economic systems
Connor: Well…
Andre: What about any other gaps in their knowledge, how will policymakers plug these gaps? I mean, there’s no reason to think that a theory, much less a full-fledged science, exists to explain every phenomenon conceivably relevant to every policy goal we might like to pursue. It is trivially true that your program could not have been implemented in a pre-scientific age, correct? The scientific material required simply did not exist.
Connor: Correct.
Andre: You have the same problem today to the extent that science is incomplete and / or indeterminate. If there are phenomena that policymakers must understand adequately in order to make an effective policy, but no theory exists that adequately explains these phenomena, your progressive program is not feasible and your policymakers are screwed. Moreover, some fields in modern science are basically brand-new. They consist of nothing but untested models or of models that are constantly in flux, constantly being revised, because, so far, they have only been falsified and no improved model has been developed. Should policymakers rely on such models, either untested or tested-and-falsified-and-not-yet-replaced?
Connor: I take the point. To the extent that a scientific consensus does not exist with respect to some phenomenon relevant to effective policymaking, the notion that science can be put to work for policy purposes is dubious. Still, you’ve yet to convince me that this is much of a problem in practice; that, when policymakers need adequate scientific input in order to make an effective policy, they will not always be able to find that input.
Andre: Oh, I’m sure there will always be people willing to offer advice, especially if there is money to be made by acting the expert, but that seems more like an invitation to charlatanism than a way to uncover scientific truth or a theoretical explanation adequate for policy purposes. The expert’s goal then becomes attracting the attention and favor of policymakers rather than the approval of one’s scientific peers. It becomes a matter of the expert convincing policymakers, ill-equipped to judge scientific truth, rather than the expert’s better equipped colleagues. Scientific controversies come to be settled by political-power considerations, rather than by experimentation, publication, and citation. That seems less like a method of making good policy than a way to screw up both politics and science.
Connor: Eh, I don’t know. Maybe.
Andre: Let me ask something else. Is the fact of a scientific consensus in some field sufficient to establish its adequacy for policy purposes? Are all scientific consensuses equal or are there some consensuses that might be inappropriate for policy purposes?
Connor: What do you mean?
Andre: A scientific consensus is just an expression of the more or less shared opinions of members of some scientific community concerning competing theoretical explanations as evaluated in the “daylight,” if you will, of the available evidence. Science is a matter of exposing various theories to this daylight to see which melt and which, if any, harden. There would seem to be at least two ways to arrive at a scientific consensus. In the first, a consensus is achieved through normal, one might say, “healthy,” scientific processes: through the development and publication of theories, open deliberation, and honest debate among scientific peers about the value of different theories, the subsequent citation – positive or negative – of relevant publications, and the eventual emergence of some considerable, if probably imperfect, degree of agreement among scientists in the relevant community. In this scenario, all of the forces pushing the scientific community toward consensus emanate from scientists and their respective appraisals of competing explanations in light of the relevant evidence; the opinions of practicing scientists regarding explanations and evidence are all that matter. However, the second route to consensus involves input from outside such a normal scientific process: in choosing between theories, scientists have to consider the attitudes, opinions, and interests of non-scientists, e.g., corporate executives, government officials, or the representatives of NGOs. Indeed, we might imagine a particularly extreme case – Trofim Lysenko comes to mind – in which a consensus is simply imposed from outside anything like the healthy scientific process I just described.
Connor: Who is Trofim Lysenko?
Jack: Another progressive who killed a lot of people.
Andre: Dammit, Jack!
Jack: Sorry, Pa.
Andre: He was a Soviet biologist who convinced Stalin of several manifestly false things, that happened to sound good to Stalin’s ears, who in turn imposed them on other biologists and—
Jack: Meaning that he imprisoned or killed them, if they refused to accept Lysenko’s line.
Andre: Yes, one assumes. But, to make matters much worse, Stalin required that Soviet agricultural plans be developed according to Lysenko’s theories. He used Lysenko’s theories as tools of Soviet agricultural policy, an experiment that ended—
Jack: Mao, too.
Andre: Right. Mao enforced a similar program based on Lysenko’s ideas in China. Anyway, these experiments ended poorly…
Jack: What you mean to say is that tens of millions of people died of famine.
Andre: Yes, that’s what I mean. I am just a bit more judicious than you.
Emma [laughs]: Ha! When you want to be.
Andre [smiles]: Yes, when I want to be, not always. Anyway, Connie, my point is that not all scientific consensuses are equal. Some emerge from within science via normal scientific processes; some are imposed on practicing scientists—
Connor: But, do we really need to worry about the ascendance of a new Stalin? That doesn’t strike me as a particularly contemporary concern. I mean, we’ve had Presidents that were immoral idiots, but none that were comparable to Stalin. I’m really not worried about the emergence of a totalitarian dictator who might wantonly impose illegitimate consensuses on various disciplines and fields of science.
Andre: Nothing I’ve said implies that a totalitarian dictator is necessary for the problem to appear. Indeed, you would agree, I assume, that a similar problem potentially appears whenever corporations or private interest groups fund scientific research, would you not? Surely, you would be skeptical of any consensus about, say, environmental pollution, that emerged from research projects funded by Dow Chemical or ExxonMobil, or of a consensus concerning the effects of smoking on lung cancer that grew out of research funded by Philip Morris or R.J. Reynolds.
Connor: Of course.
Andre: But, governments are generous funders of scientific research, too. Indeed, in some countries and in some fields of inquiry, government funding is practically the only game in town. Private actors have interests, of course, and ideologies, but so do government officials. There’s no reason – at least, you have offered no reason – to think that these officials are above acting upon their selfish interests or immune to various problematic incentives attendant upon their powerful positions.
Connor: Politicians and other government officials are generally public-spirited—at least, those of the humane and sagacious sort that I take Obama to be. They aim to maximize the public good in response to what they believe to be the general will.
Andre: That’s not an argument, Connor. That’s just to assert that politicians of the relevant sort are both above their personal interests and immune to perverse incentives. It’s an assertion of faith. Given your devout atheism, I would think you should find faith as epistemologically dubious in political as in religious contexts. But, even granting your premise that politicians are generally public-spirited, factionalized conceptions of the common good, of the requirements of public-spiritedness, can obviously emerge—aren’t these just political parties? And to the extent some faction gains adequate control of the process of funding scientific research, surely, they can distort that process in favor of their factional interests, whatever these might be.
Emma: It is remarkable how often politicians discover scientific results that support policies they would likely have promoted in any case, or, worse, policies they have already made or, worse yet, interpret their policy decisions as implications of the best science, come what may. I suppose this is just a variation on politicians’ tendency to claim success – or, at least, non-failure – for everything they do.
Andre: That’s right. It is no less in the nature of politicians to rationalize, justify, legitimize, vindicate, exalt, and glorify themselves than it is in the nature of fleas to bite. But, more to my point, even if all policymakers share a conception of the common good and aim to realize it, a false pseudo-consensus can come to be imposed from outside on an area of scientific research. It is not necessary for policymakers to be ill-intentioned or to aim at anything other than the common good for such a result to emerge. Perfectly well-intentioned policymakers can impose a false consensus on a field of inquiry, with disastrous results, no less than can venal lickspittles like Trofim Lysenko.
Connor: How so?
Andre: Imagine a case in which policymakers want – I mean, earnestly want – to bring about a result that promotes the common good, say, something concerning public health. Imagine that they want to decrease the incidence of, or the number of deaths from, I don’t know, say, heart disease or diabetes. Now, let’s stipulate that there is no scientific consensus in the fields of medical research relevant to the public-health problem that policymakers wish to mitigate. There are multiple competing explanations, each garnering roughly equal support among researchers in the field. Yet, policymakers still really want to do something to contribute to the public good. Indeed, we might complicate the example, make it more realistic, by assuming that these policymakers are under some pressure from constituents to do something about the problem at hand. Under such conditions, given the incentives they confront and their ignorance of the adequacy of available theories, what do you think policymakers will do?
Connor: I don’t know.
Andre: Given the pressure from their constituents to do something about the problem, I doubt they will just say, “We’re stumped; we don’t know what to do.” Instead, I think they’ll guess at the competing theories, pick one that they think they can justify to their constituents on seemingly reasonable grounds, and build a policy upon it. They’re surely not going to allow themselves to be interpreted as doing nothing in the face of constituent demand to do something.
Connor: That seems right.
Andre: Now, imagine that they choose poorly, that the theory they settle upon fails to explain the relevant phenomena, and that the problem is either exacerbated or simply not mitigated as a result of their ill-conceived policy.
Connor: Consider it imagined.
Andre: Now, are policymakers a humble bunch? Do they typically admit their errors?
Connor: No, I wouldn’t say that.
Andre: So, the policymakers in this example probably will not confess their mistake? Maybe constituents have no other way to discern the original error. Are policymakers likely to disabuse them and admit that the theory they guessed at turned out to be inadequate to the goal of minimizing suffering from the disease?
Connor: Probably not.
Andre: Now, what if these policymakers control much of the funding available for research in the relevant field? Are they more likely to support defenders of the competing theories that they guessed to be incorrect or adherents to the theory that they guessed to be correct, and which they subsequently built policy upon?
Connor: The latter, I suspect.
Andre: As do I. After all, funding research concerning competing theories would appear tantamount to admitting to or, at least, acknowledging the possibility of their original error.
Connor: I see that.
Andre: Now, put yourself in the shoes of an investigator in this field. You face considerable incentives to pursue research concerning the government-approved theory and to eschew work on its competitors. These incentives take the form of comparatively easy access to research funds and, as a consequence of both this and the fact that others in your field confront the same incentives, relatively better publication prospects and, ultimately, improved opportunities for tenure, career advancement, et cetera. If this is right, then the recipient of government funding is as ethically compromised as the recipient of corporate monies. If you are skeptical of self-serving research funded by oil and gas and tobacco companies, you should be no less skeptical of self-serving research that emerges from the activities of politicians, however wonderful their apparent intentions.
Connor: Eh, I’m not so sure about that. I mean—
Andre: Indeed, given that the interests of petroleum and tobacco executives tend to be obvious while those of politicians are far more obscure, you might be wise to be more skeptical of the latter. Corporate executives essentially walk around in t-shirts with their interests emblazoned across them. Politicians all claim to be well-intentioned, but who knows whether they really are, your Obama-worship notwithstanding? But, more to the point, well-intentioned policymakers can impose and, via control of research funds, enforce a false consensus on a field of scientific inquiry. There’s no need for a Stalin or a Lysenko.
Connor: I see the argument you are making, but it still seems beside the point. You’ve provided no evidence that such a scenario has ever actually occurred, much less that it is at all likely. You’ve given me no reason to worry about such a scenario.
Jack: The situation Andre just described is basically identical to the one that some have argued occurred in nutrition science in the late 1970s and which led directly to the brilliant dietary advice that the Feds have been offering for the last 30 years or so. If you’ve noticed, obesity, heart disease, and diabetes have all reached epidemic proportions over that time. And Andre did give you reasons to think that such scenarios happen with some regularity. The mere fact that policymakers possess such extensive and often exclusive control over scientific research funding, despite their comparative ignorance of science, is sufficient reason. However well intentioned, they will occasionally guess wrong, back the wrong theoretical horse, and, through their control of research funds, impose a false consensus on a field of inquiry that would have otherwise evolved in a different direction.
Connor: I suppose. I need to think about it some more.
Book Two: For Further Reading
On Policymaking and Expertise
Walter Lippmann – Public Opinion ([1922] 2010), Wilder Publications
Walter Lippmann – The Phantom Public (1925] 1993), Routledge
James C. Scott – Seeing Like a State: How Certain Schemes to Improve the Human Condition Have Failed ([1999] 2020), Yale University Press
William Easterly – The Tyranny of Experts: Economists, Dictators, and the Forgotten Rights of the Poor (2013), Basic Books
Nate Silver – The Signal and the Noise: Why So Many Predictions Fail—but Some Don't (2015), Penguin
David M. Levy and Sandra J. Peart – Escape from Democracy: The Role of Experts and the Public in Economic Policy (2017), Cambridge University Press
Philip E. Tetlock – Expert Political Judgment: How Good Is It? How Can We Know? New Edition (2017), Princeton University Press
Roger Koppl – Expert Failure (2018), Cambridge University Press
Jeffrey Friedman – Power Without Knowledge: A Critique of Technocracy (2020), Oxford University Press
On Science and Consensus
Karl Popper – Logic of Scientific Discovery ([1934] 2002), Routledge
Thomas S. Kuhn – The Structure of Scientific Revolutions, Third Edition ([1962] 1994), University of Chicago Press
Larry Laudan – Progress and Its Problems: Towards a Theory of Scientific Growth (1978), University of California Press
Larry Laudan – “A Confutation of Convergent Realism,” Philosophy of Science (1981), 48 (1): 19–49
William N. Butos and Thomas J. McQuade – “Nonneutralities in Science Funding: Direction, Destabilization, and Distortion,” Journal des Economistes et des Etudes Humaines (2012), 18 (1): 1–26
Simon Ings – Stalin and the Scientists: A History of Triumph and Tragedy, 1905-1953 (2017), Atlantic Monthly Press
Scott Scheall, William N. Butos, and Thomas J. McQuade – “Social and Scientific Disorder as Epistemic Phenomena, or the Consequences of Government Dietary Guidelines” (2018), Journal of Institutional Economics (2018), 15 (3): 431–447
On the History of Economics and Social Science
Robert L. Heilbroner – The Worldly Philosophers: The Lives, Times And Ideas Of The Great Economic Thinkers, Seventh Edition (1999), Touchstone
Henry William Siegel – The Growth of Economic Thought (1991), Duke University Press
Roger E. Backhouse and Philippe Fontaine - The History of the Social Sciences since 1945 (2010), Cambridge University Press
Lawrence H. White – The Clash of Economic Ideas: The Great Policy Debates and Experiments of the Last Hundred Years (2012), Cambridge University Press
On the History of Nutrition Policies
John Yudkin – Pure, White, and Deadly: How Sugar Is Killing Us and What We Can Do to Stop It ([1972] 2013), Penguin
Ancel Keys – Seven Countries: A Multivariate Analysis of Death and Coronary Heart Disease (1980), Harvard University Press
Gary Taubes – Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health (2008), Anchor
Book Two: Discussion Questions
1. Discuss the significance for policy experts of the tentative nature of scientific knowledge.
2. What are the consequences for the application of expertise to policymaking of the fact that science explains only some, but not all, potentially policy-relevant phenomena?
3. What are the two basic ways in which a scientific consensus can form and what is the significance of each method of formation for the value of the relevant theory as a potential policy tool?
4. Discuss the significance for policymaking of an absence of consensus – i.e., of disagreement among scientists – in some policy-relevant scientific field or discipline.