The arguments that people advance to support or oppose a proposed action rest on two kinds of support: statements about what we know, or positive claims, and statements about what we value or should value, or normative claims. These two types of claim are fundamentally different. Examine the arguments advanced in any policy debate, and you will find a combination of positive and normative claims. Examine any highly contentious policy debate - like climate change - and you will find a confused intertwining of positive and normative claims.
Making a reasoned judgment of what to do about climate change requires evaluating supporting claims of both types, and recognizing the differences between the two types of claim. Although distinguishing the two types of claim can be difficult, we argue that it is essential for understanding the debate and forming an independent judgment.
All scientific claims and questions are positive
A positive claim concerns the way things are: it says that something is true about the world. It might concern some state of affairs ("it is raining"), a trend over time ("winters are getting warmer"), or a causal relationship that explains why something happens ("smoking causes cancer"). Positive statements do not have to be simple or easy to verify, and they may concern human affairs as well as the biophysical world. "US foreign policy during the Cold War contributed decisively to the collapse of the Soviet Union" is also a positive statement, although one that would be hard to verify. What is essential to positive claims is that they concern how things are, not how they should be.
A normative claim concerns how things should be: it says that something is good or bad, right or wrong, virtuous or vicious, wise or foolish, just or unjust, and so on. Examples of normative statements would include "he should have stayed to help her," "killing is wrong," "present inequity in world wealth is unjust," "we have an obligation to protect the Earth," or "environmental regulations are an unacceptable infringement on property rights and individual liberties." With few exceptions, statements or questions that include the words "should" or "ought" are normative. And the exceptions mostly involve sloppy use of language. If someone says "the Yankees should win the World Series," he probably means that they are likely to win (a positive claim), not that it is right or just or proper that they win (a normative claim). Of course, he might mean both these things, providing an example of how we sometimes combine - and confuse - positive and normative statements.
There are several important differences between positive claims or positive questions, and normative ones.1 First, if a positive question is sufficiently well posed - meaning all the terms in it are defined clearly and precisely enough -it has right and wrong answers. Similarly, well-posed positive claims are either true or false. Second, the answer to a positive question, or the truth or falsity of a positive claim, does not depend on who you are: it does not depend on what you like or value, your culture, your political ideology, or your religious beliefs. Finally, arguments over positive claims can often be resolved by looking at evidence. If you and I disagree over whether it is raining, we can look outside. If we disagree over whether winters are getting warmer, we can look at the records of past and present winter temperatures. If we disagree over whether smoking causes cancer, we can look at the health records of a large group of smokers and non-smokers (who are otherwise similar), and observe whether more of the smokers get cancer.
But notice the word "often" that qualifies the above statement that positive disagreements can be resolved by looking at evidence. Looking at evidence cannot always resolve positive disagreements for two reasons, one philosophical and one practical. Philosophically, there is no rock-solid foundation for authoritatively resolving even positive questions, because you and I might disagree over what the evidence means. We might disagree over the validity of the methods used to compare winter temperatures in different places or over time. We might even disagree over whether what is happening outside right now counts as "rain." (Does a faint drizzle count? A thick fog?) If we are stuck in disagreement over such questions of evidence, neither of us can authoritatively win the argument. The best I can do is resort to secondary arguments, like what it is reasonable to believe, or whose judgment to trust, which you might also refuse to accept.
The second, practical limitation is that the evidence we need to resolve a disagreement might sometimes be unavailable, or even unobtainable. We cannot tell whether winters are getting warmer unless we have appropriate temperature records over the region and the time period we are concerned with. But while these limitations are real, they do not negate the broad generalization: looking at evidence provides a powerful and frequently effective means of resolving disagreements over positive claims.
This is not so for normative claims. Because normative questions always involve value judgments, the basis for believing that they have right and wrong answers is much weaker than for positive questions. Specific normative claims need to be based on some underlying set of principles that define the values at issue. These might be a set of religious beliefs or a moral philosophy, or might simply refer to people's preferences or interests (what people want, or what is good for them). But because people have deep differences over such underlying principles, the answer to a normative question can differ, depending on the moral or religious beliefs, the political ideology or culture, or the desires, of the person answering. Even a claim like "killing is wrong," which might initially appear non-controversial, elicits sharply differing views when considered in the context of capital punishment or euthanasia. Moreover, looking at evidence is of no help in resolving differences over purely normative questions. Normative questions are consequently more deeply contested than positive ones, and less amenable to mutually agreed resolution.
It should be noted that all positive and normative claims can also be cast in the form of a question, for example "murder is wrong" vs "is murder wrong?" The properties of positive and normative claims are exactly the same when cast as questions. Because of that, we will talk about claims and questions interchangeably in this chapter.
In policy debates, the arguments for and against particular actions nearly always depend on both positive and normative claims. This is because most policy choices are made for instrumental reasons: we advocate doing something because we think it is likely to bring about good consequences. Arguments about actions (Shall we raise the tax on cigarettes?) then depend partly on positive arguments about what their consequences will be (If we raise the tax, how much less will people smoke? How much revenue will be raised, from whom? How much cigarette smuggling will there be?). They also depend on normative arguments about how good or bad these consequences are (Is it fair to raise tax revenues from the poor? Is it worth accepting the projected increase in crime to gain the projected health benefits?); and on normative arguments about the acceptability or legitimacy of the action itself (Is trying to make people reduce unhealthy behavior the proper business of the government?). Similarly, people in favor of capital punishment argue that it deters people from committing heinous crimes (positive), that its application is not racially biased (positive), that procedural safeguards can reduce the risk of executing the innocent to nearly zero (positive), that murderers deserve to die (normative), and that it is just and legitimate for the state to execute them (normative). Opponents argue that deterrence is ineffective (positive), that sentencing outcomes are racially biased (positive), that the rate of errors - executing innocent people - is and will remain high (positive), and that it is wrong for the state to kill (normative).
On the climate-change issue, arguments on all sides of the debate also combine positive and normative claims. Proponents of action to reduce greenhouse-gas emissions argue that the climate has warmed, that human actions are largely responsible for recent warming, and that changes are likely to continue and accelerate - all positive claims. They also argue that the resultant impacts on resources, ecosystems, and society are likely to be unacceptably severe, and that we can limit future climate change at acceptable cost - statements that combine positive claims about the character of expected impacts and the efficacy of responses, with normative claims about the acceptability of these costs. All these claims, positive and normative, have been disputed by opponents of action to reduce emissions.
But while policy arguments may involve both positive and normative claims, these do not come neatly identified and separately packaged. Rather, many arguments intertwine positive and normative elements. For example, consider the statement, "the science of global climate change is too uncertain to justify costly restrictions on our economic growth." This says that restrictions on emissions are not justified, which appears to be a normative claim. But the claim also depends on unstated assumptions about positive matters, including what we know (and how confidently we know it) about how fast the climate is likely to change, what the impacts will be, what means are available to slow the changes, and how costly and difficult these are likely to be. The person making this argument may have considered all these things in reaching her judgment that restrictions on emissions are not justified. But hearing this argument, you would have to consider whether she is correct in these assumptions to reach an informed view of whether or not you agree with her conclusion. You and she might agree completely on what level of scientific knowledge is sufficient to warrant action, but still disagree on the conclusion if you disagree on the state of scientific knowledge.
The unstated assumptions behind an argument can be normative as well as positive. Consider the statement, "the Kyoto Protocol would cost the US economy hundreds of billions of dollars while exempting China and India from any burdens." This says something about the costs of a particular policy, which sounds like a positive claim. But the statement also has rhetorical power, since it strongly implies that it would be wrong or even foolish for the USA to join the Kyoto Protocol. Whether the statement is correct or not as a positive matter, it gains this rhetorical force from several unstated assumptions, some positive and some normative: that this cost is too high, relative to whatever benefits the Kyoto Protocol might bring the USA; that imposing the initial burden of emission reductions on the rich industrialized countries is unfair; and that other courses of action open to the USA are better.
This tangling of positive with normative claims, and of explicit arguments with powerful unstated assumptions, obstructs reasoned deliberations on public policy. It creates confusion, exacerbates conflict, and makes it difficult for citizens to understand the argument and come to an informed view. This tangling might be inadvertent, or might be intended to sow confusion in the debate, so as to obscure areas of potential agreement. The pieces of an argument cannot always be perfectly disentangled, of course. But untangling them to the extent that is feasible, and making the major assumptions that underlie policy arguments explicit, can often reduce conflict and identify bases for agreed action among people of diverse political principles.
Separating positive from normative claims is particularly important for environmental issues because of the central role positive claims play in these debates. Participants in environmental policy debates nearly always try to ground their policy arguments on scientific claims, even though the other side is often advancing directly contradictory scientific claims. In the climate-change debate, one advocate might say, "scientific evidence shows that the Earth is warming," while another says, "there is no scientific evidence that the Earth is warming." Resolving disputes over positive claims can make a substantial contribution to reducing disagreement over what course of action to pursue.
And such resolution is often possible. Indeed, on many environmental issues, the state of relevant knowledge is much more advanced and the scientific agreement much stronger than you would think from reviewing the policy debate or reading the newspaper. This is emphatically the case for global climate change. We know more about the climate, how it is changing, and how it is likely to continue changing under continued human pressures, than a look at the policy debate would suggest. To understand why, we first explore how the social process we call "science" works. We then explore how political decision-making works, and what happens when these two very different social processes come into contact with each other.
Continue reading here: How science works
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