Saturday, October 31, 2009

Scientific Claims and Falsifiability

In my previous post I argued against an economist's criticisms of scientist's claims on truth. Arnold Kling does a much better job of making a similar criticism stick.

Arnold's argument boils down to this: Scientists sometimes claim that they will soon make particular discoveries or uncover particular knowledge, when in fact there is great doubt about whether they will.

These claims of impending success are common, and commonly wrong. More to the point (as Arnold suggests) these claims are unscientific, and therefore unbecoming to professed scientists, precisely because they are non-falsifiable. There is no theoretically possible method to disprove these claims (at the time they are made).

Science deals exclusively with claims that are (in principle) falsifiable. This is an extremely important part of why science works at all. By limiting scientific inquiry to falsifiable claims science is made testable and, ultimately, meaningful. If I believe that a scientific claim is false, I need only devise an experiment that will demonstrate a conflict or contradiction in order to prove that it is false.

Imagine what would happen if non-falsifiable claims were included under the domain of science. Under such a system scientists would concern themselves with claims that are mutually exclusive, but with no ability to distinguish between the truth or falseness of either. The discovery of knowledge would slow as time and effort were consumed in pointless and unending argument...

This is a concept that I'm sure all scientists are taught at some point early in their education. However, as important and fundamental as falsifiability is, many scientists seem to forget about it, or even become confused about what it means. Take, for example, Richard Dawkins' invocation of Russell's Teapot in support of militant Atheism. The bizarre thing here is that Dawkins uses Russell's Teapot as an example of a non-falsifiable claim, and therefore outside of scientific notice, while he simultaneously argues in favor of militant Atheism - which is a non-falsifiable claim as well. How can a scientist of such standing be so confused about one of science's founding principles?

Note: It  is important to recognize that Russell's Teapot may actually be a falsifiable claim, and therefore within  the purview of science. If you claim that there is a teapot in orbit, AND describe the orbit and the teapot in sufficient detail, then the claim is clearly falsifiable because the absence of the teapot in the specified orbit could, in principle, be observed. Militant Atheism, however is not a falsifiable claim because it is not possible, even in principle, to observe the absence of a god who can tweak the universe and human observation to achieve whatever end he/she/it desires. Militant Atheism must perforce fall outside of the notice of science.

Friday, October 30, 2009

Soft vs Hard Science?

Eric Falkenstein has made some sweeping generalizations about scientists. It's always a bit of a puzzle to me when I hear these kinds of arguments. When I look at the world around me I see the application of science everywhere. If scientists don't have a special claim to truth, then either my DVD drive shouldn't work, or communism should.

OK, that needs some explanation. First, my DVD drive:

Einstein discovered the principle of Light Amplification by Simulated Emission of Radiation (LASER, of course) while working on another problem. A few decades later his work was demonstrated to be correct when the first functional laser was built. Einstein's claim to truth is irrefutable, as are the claims of subsequent scientists and engineers who gradually refined the understanding of the concept until my DVD drive could be mass produced and sold to me.

What about communism? Well, economics is something of a science, but it's not a terribly successful one. Communism is a failure precisely because economic principles are not well enough understood to construct powerful and useful technologies for planning and coordinating the efforts of millions of people. Economics doesn't have a LASER equivalent. But, even though economics has not produced a lot of useful or even agreed upon knowledge, there are still many economists who have a need to publish in order to move their careers along. I think this is at the heart of what Eric Falkenstein is criticizing.

But why attack scientists altogether? To my mind, there is a genuine distinction between the hard and soft sciences, and that distinction is most visible in the technologies that emerge, or fail to emerge, from the knowledge that various kinds of scientists produce. After all, the purpose behind science isn't only to gain understanding, but to gain useful understanding that can be applied to better our lot.There's no need to conflate physicists with economists when their relative accomplishments are so distinct.

Alas, Eric doesn't note the distinction, and instead slanders 'physical' scientists while levying accurate criticisms against economists and other 'social' scientists. Maybe he does this because he's not prepared to countenance the disparity.

Thursday, October 29, 2009

Does Natural Selection Account for All Biophenomena?

No. But too many people who like to dabble in evolutionary explanations assume that it does.

The book, How Women Got Their Curves and Other Just So Stories is a good example of this. Many hypotheses are put forward for this or that characteristic or behavior, all explained in terms of selective pressure acting upon our forbears. We are as we are precisely because our clever genes have tried out various reproductive strategies, and the cleverest genes have won out.

What the authors fail to consider is the missing evidence.

Hair color can illustrate what I mean. Has hair color been strongly selected for? Are brunettes more common than redheads because brunettes possess an evolutionary advantage? Probably not. After all, there are many different common shades and hues, and no obvious advantage of one color over another presents itself. One might point out that light-colored hair is correlated with light-colored skin, which does possess an evolutionary advantage for people in northern lands. But one needs only to travel to the Caucasus to find that light-skinned people can have dark-colored hair.

So, maybe hair color has not been strongly selected for. Perhaps it is merely the result of chance, isolated populations, and group identity that Swedes tend to be blonde while Han Chinese are nearly uniformly dark-haired. Indeed, a fundamental mechanism at work within evolution is chance mutation. Only after a feature has appeared, as the result of a genetic accident, can the feature become the subject of selective pressure.

Imagine, for a moment, a world in which a Great Calamity early in human history has by chance killed off the ancestors of all modern humans except for a small group who were to become the forbears the Chinese. In such a world, nearly everyone would have dark hair since we all would have descended from the dark-haired survivors. Scientists studying evolution in that world would perhaps, upon considering themselves and their fellows, conclude that it must be the case that there had been some strong advantage to their ancestors in having dark hair, since human chemistry could permit other hair colors but no living humans were in fact so colored. The missing evidence that could have revealed the truth, died with the proto-Europeans in the Great Calamity.

Such scenarios have in fact happened repeatedly throughout the history of life. Why are the creatures that have built universities, governments, and shopping malls descended from the ancestors of marmots instead of from the ancestors of falcons? Because of a chance extinction and climate change that gave mammals an opening against dinosaurs.

Indeed, assuming that a trait has been selected for merely because it exists, or even because it is common or exclusive, is bad science. Science demands evidence to connect premises with conclusions (reasoning alone is not sufficient). Evolution is powerful science, and may be invoked in the work of others who are seeking to describe the world, but there is more to Evolution than selective pressure.

The Reason

I intend to use this blog to organize and direct my thinking. Publishing to a public forum helps me to see the weaknesses in my positions, and to verbalize the strengths that might otherwise be left unexpressed and unexplored.

I am a mechanical engineer by profession and training. I am not an academic, nor do I possess advanced degrees (I am pursuing a masters in engineering). However, I am interested in economics, history, science, policy, and philosophy, and will seek to discuss these and other things. I approach these subjects as an amature.

I don't write for an audience, but I encourage you to argue with me when you think I'm wrong. Just please do so courteously and thoughtfully. I promise to do likewise.

--Robert Johnson