by Judith Curry
There is an interesting new article at boingboing entitled “Lowercase theories, uppercase Theories, and the myth of global cooling.” (h/t Keith Kloor).
“Fifteen hundred years ago everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the Earth was flat, and fifteen minutes ago, you knew that humans were alone on this planet. Imagine what you’ll know tomorrow.”
Men In Black’s Agent Kay isn’t exactly a great public philosopher, but I think he does do a good job of summing up the reason why some people don’t like the idea of applying the science of climate change to the realm of political policy. Science changes, after all. Who’s to say that 100 years from now we won’t find the results of 21st century climate modeling as ridiculous as a map of a flat Earth?
This argument isn’t totally off-base. Scientific theories are frequently overturned by new evidence. But, just as often, the new evidence changes one part of a theory, while leaving the big picture intact. That’s because scientists use the same word–”theory”–to describe two very distinct classes of ideas. Gravity is a theory. But so is the existence ofGliese 581g–a wobble in the light given off by a distant star which may, or may not, turn out to be a planet. One of these things is not like the other. Of the two, new evidence is much more likely to disprove the existence of Gliese 581g.
Scientists still study what gravity is and how it works. It’s a living theory, not a cold, unchanging edifice. In fact, there’s a lot of weird, little anomalies that tell us we don’t have this gravity thing totally figured out just yet. But as new evidence comes in, it tends to refine the details, not demolish everything we thought we knew. Einstein revolutionized the theory of gravity, but he didn’t make apples start to fall up.
The article discusses the state of the debate in the 1970′s including global cooling. It concludes:
The 1975 NAS report on climate science reflects the confusion that surrounded the field at that time. In fact, the introduction flat out says, “…we do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding, it does not seem possible to predict climate…” There wasn’t anything close to a scientific consensus on climate in 1975. But that was about to change rapidly. Over the next five years, research methods improved, more papers were published, and all those little theories began to add up to a single big Theory–the Earth was getting hotter.
By 1979, it was already clear that the effect of greenhouse gases had a bigger impact than the effect of dust particles. When the NAS came back to the subject of climate science that year, the state of research had changed enough that their summary was now very different. Instead of uncertainty, the 1979 NAS report emphasized a message that was, basically, the same as what we still hear today: The Earth is warming, and that fact should not be ignored. The popular press liked the story of global cooling. But their interest in that story didn’t reflect what scientists were actually thinking. There was no flip-flop of science here.
Instead, what happened in the 1970s was that science worked the way it’s supposed to work.
Researchers identified an important question. They studied it. They figured out how to study it better. And, slowly, between roughly 1970 and 1980, they came up with a broad, generalized answer. They went from a jumble of lowercase theories to an uppercase Theory.
Since then, the uppercase Theory hasn’t changed. No new evidence has surfaced to challenge it. Instead, researchers have busied themselves with the details—studying the lowercase theories within climate change to try and make that big Theory more specific. What they’ve learned has made them more and more certain that the big Theory is correct. So, in a way, the scientific consensus certainly has changed since 1975. But it changed from, “We don’t know,” to “Climate change is definitely happening.
The article raises some interesting issues, but IMO doesn’t quite sort out Theory vs theory in the climate change debate. As far as I can tell, a lower case theory is equivalent to an hypothesis
Lets take a closer look at scientific laws, theories, and hypotheses. Some good definitions are provided by this link:
Scientific Law: This is a statement of fact meant to describe, in concise terms, an action or set of actions. It is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation. Scientific laws are similar to mathematical postulates. They don’t really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true.
Specifically, scientific laws must be simple, true, universal, and absolute. They represent the cornerstone of scientific discovery, because if a law ever did not apply, then all science based upon that law would collapse.
Some scientific laws, or laws of nature, include the law of gravity, Newton’s laws of motion, the laws of thermodynamics, Boyle’s law of gases, the law of conservation of mass and energy, and Hook’s law of elasticity.
Hypothesis: This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation or continued observation.
Theory: A theory is what one or more hypotheses become once they have been verified and accepted to be true. A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers. Unfortunately, even some scientists often use the term “theory” in a more colloquial sense, when they really mean to say “hypothesis.” That makes its true meaning in science even more confusing to the general public.
In general, both a scientific theory and a scientific law are accepted to be true by the scientific community as a whole. Both are used to make predictions of events. Both are used to advance technology.
In fact, some laws, such as the law of gravity, can also be theories when taken more generally. The law of gravity is expressed as a single mathematical expression and is presumed to be true all over the universe and all through time. Without such an assumption, we can do no science based on gravity’s effects. But from the law, we derived the theory of gravity which describes how gravity works, what causes it, and how it behaves. We also use that to develop another theory, Einstein’s General Theory of Relativity, in which gravity plays a crucial role. The basic law is intact, but the theory expands it to include various and complex situations involving space and time.
The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law describes a single action, whereas a theory explains an entire group of related phenomena.
A theory is like the automobile. Components of it can be changed or improved upon, without changing the overall truth of the theory as a whole.
Some scientific theories include the theory of evolution, the theory of relativity, the atomic theory, and the quantum theory. All of these theories are well documented and proved beyond reasonable doubt. Yet scientists continue to tinker with the component hypotheses of each theory in an attempt to make them more elegant and concise, or to make them more all-encompassing. Theories can be tweaked, but they are seldom, if ever, entirely replaced.
Application to climate science
The foundation of climate science rests on fundamental laws such as Newton’s laws of motion, Planck’s Law and the Stefan Boltzmann Law, the first and second laws of thermodynamics, ideal gas laws, gravitation, conservation of mass and energy. Debates about these laws in the context of the climate debate are pointless (although that doesn’t stop some people).
There are numerous theories of complex processes (collections of hypotheses) that contribute to our understanding of climate science, including the theory of rotating fluids, the theory of boundary layers, the theory of gaseous infrared spectroscopy and radiative transfer. These theories are widely accepted, although there is much energy expended by the skydragon group in refuting the theory of gaseous infrared radiative transfer (which is completely pointless IMO in any manifestation that I have seen of such arguments).
The theory of greenhouse warming of the climate system is a meta theory that incorporates many hypotheses and theories about how components of the earth system work. I regard as a hypothesis (or perhaps as a lowercase theory) the specific issue of the magnitude of the climate sensitivity in response to a doubling of CO2. The various and wide ranging estimates of climate sensitivity indicate how far hypotheses of climate sensitivity are from being established as a theory that is supported with repeated testing.
JC comments: In making arguments for AGW to the public, scientists explain the Tyndall gas effect and gaseous infrared radiative transfer, which are well established theories. These well established theories are then bootstrapped to provide plausibility to quantitative statements about the magnitude of climate sensitivity to greenhouse gas forcing. This has been enormously misleading IMO. This is the confusion of the uppercase Theory versus the lowercase theory. Scientists agree on the uppercase Theory, but disagree on the lowercase theory, with multiple hypotheses about the lowercase theory.