Behind the global warming or climate change debate is a lot of good chemistry, climatology, geophysics, and other science. But more central to the debate even than meteorology is Logic, one of the tools of the scientist. To analyze the debate we must peel apart the layers of logic, to see what we discover. I personally take no position on global warming, other than having my innate cynicism alerted when politicians dabble in science and vice versa.
The debate is about changing public opinion, because public opinion leads to public policy decisions, and policy decisions mean power and money. In the debate we find the usual techniques of sophistry used to great effect. We shall see many fallacies, and hopefully shed some light on some areas shrouded in the darkness of ostensible openness. Let us begin with the first layer, what I consider to be the most fundamental.
The Burden of Proof
The kind of logic practiced in rhetoric, law, and scientific writing is called 'informal logic'. It is a basic principle of informal logic that the Burden of Proof is always on the one making the assertion.
To show that societal changes are needed to combat global warming, proponents should not assume it proved that global warming is occurring or that certain changes are needed, asking doubters to show otherwise. Proponents of the theory of man-made or Anthropocentric Global Warming (AGW) must show:
- That the Earth is getting warmer (by whatever cause)
- That the warmth is on balance harmful to humans, directly or indirectly
- That some step of remediation or mitigation is likely to be better for us than some other course of action.
On the other hand, since with the assertion goes the burden when challenging a particular proposition made by AGW activists, AGW deniers may find themselves in the same boat. In either case, failing to take on the burden of proof may mean that an argument is convincing only to those who already agree with its conclusion.
For some time, opponents of the theory of AGW have been arguing that only pro-AGW ideas are getting any attention in the news media and in scientific journals due to what can loosely be called political correctness. Proponents of AGW have charged that the Bush Administration has suppressed scientific reports, or edited them for content away from AGW.
Suppressing evidence is bad science, whether the evidence is politically popular or not. However, it is equally bad for scientists to tailor their findings politically as it is for politicians to do so for them. In any case, the suppression of evidence is not evidence, and charging suppression is not suppression. In the age of the Internet, for a scientist to claim inability to find a platform from which to speak seems most disingenuous.
The next layer is hidden by the legitimate workings of the research process, making it difficult to spot: a combined Appeal to Authority and Appeal to Popularity. But a chain of two fallacies is still fallacious. The number and reputation of learned people who believe a proposition may affect how an idea spreads, but popularity does not affect truth or falsehood.
In a court of law, for instance, the truth is not determined by the number of experts one can line up to agree, else the better-funded or organized side would always win. It is up to the experts to present evidence, based on their experience and knowledge. The other side counters with expert evidence of its own, and the judge or jury evaluate. It is not the number of experts that decide the case, but the quality of the arguments each side can present. If a hundred experts declare that day is dark and night is light, the judges should find with one opposing expert noting the time and pointing to an open window.
Scientific Fact and the Zone of Conflict
Similarly, scientific belief is not, or should not be, formed on the basis of the number of scientists who believe one way or another.
All science is by definition unproven on some level; each fact is only accepted, not proved in the sense that a mathematician or logician proves something. For example, we don't know the speed of light, or that momentum is always conserved, and so on, only that according to observation and reasoning based on all of our observations to date, that the accepted fact or principle is reliable. Scientists speak of 'facts', but always with the knowledge that these 'facts' can be challenged. Challenging accepted facts requires supplying evidence and reasoning to counter them. It does not mean arranging a vote on the matter.
Experts on a given topic argue about it. The breadth of their discussion on a given topic varies, usually trending from the fundamental to the esoteric with the time and depth of study applied to the topic.
The number and reputation of scientists who accept something as probable or as fact only indicates the approximate parameters of the debate that surround a given idea. This can be thought of as the Zone of Conflict, the area for a given topic outside of which the facts are largely settled among experts. New evidence, or new arguments about old evidence, can change the popularity of a proposition, and thus expand or contract the Zone of Conflict in the field of study which pertains to that proposition, but they do not change its truth or falsehood.
There is a fallacy lurking underneath the 'experts agree' layer and the 'scientific fact' layer, by which some seek to discredit a scientist or lay person based on how close his ideas are to Zone of Conflict. Conversely, some like to point out that no fact is ever totally proved, and thereby invent a controversy of fact when none really exists. Stating that all things are uncertain does not challenge a fact, any more than asserting a fact makes it so.
It is an Appeal to Ignorance to claim that because of the existence of the Zone of Conflict, any claim about that topic is as likely to be true as any other. But it is an Appeal to Authority to claim that an argument is invalid because it is outside the Zone. In general, the range of discussion that takes place on a topic says nothing about the validity of a particular argument or the truth of a particular proposition.
Since the Burden of Proof is on the one making the assertion, it is the responsibility of the one who would expand the Zone of Conflict to show that a real question exists. Conversely, properly rebuffing such an attempt requires actually showing that the matter is settled and why the question is no longer open.
A Straw Man for Illustration
An example of how the Global Warming Debate is typically waged is on this page, in which some arguments against AGW are listed, then attacked. The page says that its opponents say that "the science is unproven" and that for various reasons scientists can't be trusted. It says opponents say that we can't trust the scientists, because they are politically prejudiced liberals who have been wrong before and have financial incentives to lie.
To counter the argument that the science is unproven, the page goes into long and laborious treatment of the glories of scientists of the past, their discoveries and insights, as if that illustrates the correctness of these scientists on this topic, which of course it does not. But the main point of the supposed lesson on the history and philosophy of science is to say, as above, that asserting the unproved nature of scientific fact is a red herring, since all facts are unproved. The page fails to take into account, however, the Zone of Conflict, leaving unanswered the question of whether the facts of AGW are more like the well-understood principles of Newtonian physics or the little-understood composition of vacuum.
The primary fallacy the page commits is misplacing the burden of proof. While the author of the page may accept the science behind AGW, that doesn't mean that others do. The burden of proof is on the one wanting to change things. The page concludes:
Global warming is a serious problem, but even more serious, in my thinking, is the intellectual dishonesty used in denying it. Global warming deniers are of the same feather as Holocaust deniers. The truth is blatant, the data overwhelming, but they continue to spread their lies. If we let these dissemblers influence our policymaking any longer, we will pay a high price for our foolishness.On the other hand, the absence of a proof is not a disproof, and the presence of a fallacious argument does not mean that a sound argument cannot be made. In this instance, while the page attempts to press the case for Global Warming by discrediting the arguments against it and insulting those who make them, doing so is batting down a straw man. It is, ironically, the same tactic I would be adopting if I were to claim that the page represents the entire pro-AGW argument.
The Anthropocentric Global Warming Argument
Here is an outline of the pro-AGW argument. I use 'greenhouse gases' as a shorthand for methane, CO2, water vapor, and others; it is not my intention either to mislead or gloss with the label, but only to condense the argument:
- The Earth is warmer, and will be warmer still, because of increased levels of greenhouse gases.
- Average global temperatures have risen in the last century.
- There is more greenhouse gas in the atmosphere in the last century.
- Man has been putting the gases there, and continues to do so.
- A greenhouse gas increase causes an increase in global temperature.
- Computer models show that nature will not mitigate global warming on its own
- Warm temperatures are bad.
- They melt polar ice
- They thaw tundra, releasing stored gases, compounding the problem
- They make plains into deserts
- Computer models tell us these things, and worse, will happen
- Emissions are associated with other pollutants.
- Therefore, to fix global warming we should limit production of greenhouse gases.
To expect permanent stability in climate patterns displays a fundamental lack of understanding of the complexity and instability of weather.Similarly, that there are higher concentrations of certain gases in the atmosphere sounds important, but even if the changes in concentrations match precisely the temperature changes, which has not been shown, it does not mean that the gases caused the temperature change. What is required here is experimental evidence of causality, which is difficult to produce on a planetary scale.
Proposition A, we see, is an example of the fallacy cum hoc ergo propter hoc, which is Latin for "with this, therefore because of this". Just because two things happen together doesn't that mean one caused the other. The two could be unrelated, there may be other factors which are more instrumental, or the supposed effect could be the actual cause. Even if the supposed cause is generally known to have the effect in question, timing does not imply causality for any particular observation.
In the case of Global Warming, it has not been proved that increased greenhouse gas levels are the cause, or the major cause, of higher temperatures.
Computer models have been developed to show that the increased gas levels are the cause of higher temperatures, and furthermore, to predict future conditions based on various emissions patterns. But the computer models are the work of experts. The experts assert that the work is trustworthy. So we are left again with trusting the experts not only to have thought of everything, but to have accounted for their own biases while doing so.
The presumption that a group of experts formed into a scientific Society is more trustworthy than a single expert assumes that the independence of the experts is stronger than the pressure in such a society to conform. As far as I know, this has not been established. Further, some scientific groups are politically active on a range of issues, which gives the appearance that their opinion is derived from something other than purely scientific input. The introduction of points against greenhouse gas emissions that are irrelevant to the AGW argument tend to illustrate this point.
In the decision, we have four cases, all of which hide complex issues of their own:
- If the pro-AGW side is right and we do nothing, we face a radical change in world climate
- If the pro-AGW side is right and we act, and the changes work, we have the same climate but an uncertain economy
- If the pro-AGW side is wrong and we act, we have an uncertain economy for nothing
- If the pro-AGW side is wrong and we do nothing, life goes on
We also don't know that warmer temperatures will be bad for humans. Warmer temperatures would seem to complicate the lives of polar bears and coral, but there is a link missing between those complications and radically changing the world economy, when it is quite possible that the warmer temperatures would improve live for humans and other life forms. It could, in fact, dramatically simplify life for humans in climates formerly too cold to inhabit; polar bears might adapt to life without ice; and coral might just grow in seas currently too cold for it.
I do not fault any who accept the opinion of experts that AGW is real. Nor do I fault the scientists, far more able than I, who judge that CO2 levels are to blame for higher temperatures. And since they accept those premises, actively trying to avert a possible disaster is understandable.
However, the links have not been properly made. In a controversy, the side seeking change from the status quo should be able to prove its case. AGW proponents need not show that the Earth is warming, which basically everyone accepts, or even that man is the cause of the warming, which many do not. But it must be shown that human action is both necessary and sufficient to fix global warming, and that the probable benefits to mankind outweigh the costs. Since what is at stake is so drastic, I demand greater proof than has been thus far offered.
The debate over man-made climate change may in the end devolve into a popularity contest between those who accept the unproved causal link and those who remain unconvinced. I can accept the results on a political level, since it is generally good to accept the advice of experts.
Just don't call it science.
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