Something for the AGW Skeptics to Ponder

[piston]

This is Maine. It's the 20th of March, 11:10 P.M., and our living room windows are ... opened.

[piston]

Girls have started to tan. They're actually laying on the ground, tanning!

[piston]

There's been no bulging river flowing over the dam.

[piston]

Tulips are popping out of the ground.

[piston]

I have given little Carter a ride around the block in his baby car, without a hat on his head. He was blinded by the sun.

[piston]

We're just about ready to grow potatoes....

[Corlyss_D]

You know weather isn't climate, Jacques.

I envy you. We had a freak snow storm blow thru Fri. Our temps are slightly but not terribly below normal here, but on an upward sloping curve. The birds have returned in force. I've got the Lawn Dr. coming with pre-emergent two weeks from now, and hope that the ground stays snow-free till he does. Another storm is due next week. I see the farmers have plowed their fields already. Last year spring was 6 weeks late and they couldn't get their crops in the ground. I don't grow anything on my 1 acre, but I do admire the industry of those who do. How big is your garden? Or do you have a farm?

[living_stradivarius]

And anecdotes aren't scientific evidence You know this winter was the first in two decades that snow fell in San Fran. And one of the colder ones in Minnesota (with plenty more snow to boot).

[Brendan]

Same as last year and the year before and the year . . . here. Cooling down before Easter, last rose blossoms coming through before the camelias take over . . .

By Anzac Day, the cool will be in to stay. As ever.

[rwetmore]

A certain amount of abnormal weather is normal.

[DavidRoss]

In keeping with the thread title, it seems appropriate to note the following observation by the eminent philosopher of science, Karl Popper:

"Our belief in any particular natural law cannot have a safer basis than our unsuccessful critical attempts to refute it."

Everyone interested in the scientific basis for AGW (or any other theory) should understand the principles addressed by Popper in the following brief essay, Science: Conjectures and Refutations.

[rwetmore]

In keeping with the thread title, it seems appropriate to note the following observation by the eminent philosopher of science, Karl Popper:

"Our belief in any particular natural law cannot have a safer basis than our unsuccessful critical attempts to refute it."

Everyone interested in the scientific basis for AGW (or any other theory) should understand the principles addressed by Popper in the following brief essay, Science: Conjectures and Refutations.

I like these:

"These considerations led me in the winter of 1919-20 to conclusions which I may now reformulate as follows.

(1) It is easy to obtain confirmations, or verifications, for nearly every theory-if we look for confirmations.

(2) Confirmations should count only if they are the result of risky predictions;that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory-an event which would have refuted the theory.

(3) Every "good" scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.

(4) A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of theory (as people often think) but a vice.

(5) Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability; some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.

(6) Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of"corroborating evidence.")

(7) Some genuinely testable theories, when found to be false, are still upheld by their admirers-for example by introducing ad hoc some auxiliary assumption, or by re-interpreting theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later described such a rescuing operation as a "conventionalist twist" or a "conventionaliststratagem. ")

One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability."

[Corlyss_D]

And anecdotes aren't scientific evidence You know this winter was the first in two decades that snow fell in San Fran. And one of the colder ones in Minnesota (with plenty more snow to boot).

I don't know if it is the first, but snow was surely a surprise to the Arizonans and the Texans and the Floridians.

A winter storm moving through the South could means that there will be snow on the ground in all 50 states, which has likely never happened before. Snow in Florida clinched it, according to the Patrick Marsh of the National Severe Storms Laboratory. Meanwhile, Dallas snowfall has reached a single-day record yesterday, with 12.5 inches falling within 24 hours at DFW Airport.

For there to be snow on the ground in all 50 states, the current storm in the South would have to dump onto the Florida Panhandle, which just happened. University of West Florida cancelled classes due to snow.

[Brendan]

Unfortunately, Popperian falsifiability just isn't the slam-dunk many of us hoped it would be:

A major line of argument against falsifiability originates with Pierre Duhem’s thesis of the non-falsifiability of isolated scientific hypotheses. In his words: ‘In sum, the physicist can never subject an isolated hypothesis to experimental test, but only a whole group of hypotheses; when the experiment is in disagreement with his predictions, what he learns is that at least one of the hypotheses constituting this group is unacceptable and ought to be modified; but the experiment does not designate which one ought to be changed.’ The ‘whole group’, to which Duhem refers, involves a complex network which includes: background knowledge, ‘hard core’ theories (e.g. Aristotle’s two-domain laws of motion or the three laws of motion in Newton), auxiliary hypotheses (such as explain the workings of the radio telescopes in astronomy and legitimate the ‘observed results’ as evidence), and the hypothesis under test. The logic of falsification cannot target the hypothesis under consideration nor compel its rejection. The logic can guarantee only that somewhere something is amiss. It does not tell us where to look, or how to locate the source of the trouble.
. . .
Since Duhem first argued his thesis, subsequent philosophers of science (most notably W.V.O. Quine, Thomas Kuhn and Imre Lakatos) have both developed its argument and expanded its thesis. And even Karl Popper, the champion of falsifiability, has successively revised his position in response to Duhemian criticisms such that it closely resembles that of Lakatos. The clear result is that the distinctive advantage of modus tollens is lost and the Popperian programme of falsification is no longer tenable. Its hard demarcation thesis wanes, and history enters into its rationality.
Balestra, Dominic J. – Science and Religion [Cassell 1998 Davies, Brian ed pp352-353]

This does not, of course, render AGW scientifically credible as yet. Falsifiability is a good rule-of-thumb, like Occam's Razor, but is hardly physical law - or even very useful for actually doing science or philosophy of science. A shame, really, but often such notions become more slippery upon deeper examination.

[DavidRoss]

Unfortunately, Popperian falsifiability just isn't the slam-dunk many of us hoped it would be:

This does not, of course, render AGW scientifically credible as yet. Falsifiability is a good rule-of-thumb, like Occam's Razor, but is hardly physical law - or even very useful for actually doing science or philosophy of science. A shame, really, but often such notions become more slippery upon deeper examination.

No, the difficulty in some circumstances of pinpointing exactly what a given experiment may be falsifying suggests limits to the usefulness of falsifiability but does not invalidate it.

The point of introducing Popper's statement was not to start a discussion on progressively subtler issues in the philosophy of science, but to try to help Piston understand that AGW is not "scientifically proven" just because some observations can be interpreted to support the theory...and that investigating evidence that contradicts the theory is not "unscientific" and hostile to the truth, but rather is essential to scientific inquiry and honest efforts to understand the world around us.