Wednesday, December 30, 2009

Science and Philosophy, Part II: Thomas Kuhn

Thomas Kuhn objected to Popper's positivist approach to science. Although Popper set a high bar for what he regarded as "scientific," he nevertheless believed that humans can and do make steady progress in learning more about the world. Kuhn was more sceptical; he thought that the best we could do is come up with more and more sophisticated models of reality, without, however, approaching "truth" (knowledge of the Ding-an-sich, or what really lies behind our models).

Kuhn's inspiration was what he called "the Copernican revolution." Prior to Copernicus, Western astronomers since Ptolemy had worked out a very detailed model of how the planets, sun, and stars revolve around the earth. To make their model match observations, they had to add layers of complexity: celestial bodies not only moved in great circular orbits, but also sometimes in smaller orbits around a point in their major orbit (see the explanation and diagram at Wikipedia). Sometimes there were epicycles on epicycles. It was a messy model. Copernicus created his model of a heliocentric solar system partly because it allowed him to dispense with some of the complexity of the older Ptolemaic system. His model was no more accurate, but it appealed to him because it was simpler.

Kuhn described the shift from a Ptolemaic to a Copernican astronomy a "paradigm shift." It was not the result of a gradual improvement in science through falsification or any other such method, but a radical rethinking of the universe on new terms. To him, this proved that Popper's rigorous scientific method did not lead to an ever-closer approximation of the truth, but rather to ever more sophisticated models of reality. He compared these models to human evolution, which has seen homo sapiens evolve from primitive, simple forms to ever more complex forms; and yet humans are not evolving toward any particular end, just as scientific models are not evolving toward any particular truth.

I was with Kuhn up until the analogy with human evolution. For one thing, it is curious for him to point to scientific models as ever more complex, when one of his points with the Copernican revolution is that Copernicus's model was actually simpler than what it replaced. More important, while I see his point that scientific models are only models and not an actual representation of the Ding-an-sich, I find his analogy fundamentally flawed. Humans are not evolving toward any particular end, but science is not the same as evolution. It is true that Copernicus's paradigm of planets orbiting in circular patterns around the sun was not perfect, and would be subject to further revisions by later astronomers, notably Kepler's insight that orbits are elliptical.

On the other hand, there is something fundamentally right about Copernicus's idea. No one is ever going to discover that the earth really is the center of the universe after all, and that the planets and sun are really revolving around it while it remains stationary. They can't, because it is wrong. Neither is anyone going to demonstrate that Kepler was wrong and orbits are really circular rather than elliptical. Unlike evolution, scientific advances cannot travel down certain paths. We may lose knowledge, and people may be deceived for a time, but a scientific advance is not repealable in the logical sense.

I can't quite express my ideas in rigorous terms, because I know that it's possible for scientists to be mistaken; I can't, therefore, assert that science is always moving toward truth. On the other hand, I feel that there is a truth in Copernicus's ideas that go beyond mere modelling to represent what actually happens in the solar system better than the Ptolemaic system. I'm convinced, therefore, that Kuhn is wrong, without being able to come up with a complete theory of my own to replace his.

Tuesday, December 29, 2009

Science and Philosophy, Part I: Hume and Popper

I've been listening to a lecture series on philosophy recently, and, even though I haven't gotten past the Greeks yet, it has reminded me of a number of issues that trouble me about science. I want to take the opportunity to express my concerns here. Along the way, I will probably oversimplify philosophy a great deal -- not on purpose, but rather because I have only a simplistic understanding of it. I welcome responses to clear up my misconceptions.

One of my issues with science is the famous idea of Karl Popper that it can never establish positive claims, only falsify wrong ones. The history of this goes back to David Hume, the 18th century Scottish sceptic. He shook up the philosophical world by claiming that science could never prove anything through induction -- that is, drawing conclusions about physical laws based on observations. The classic illustration is the sun's rising. Even though the sun has risen every day for our whole lives, and for countless human lives past, we cannot therefore conclude that the sun will rise tomorrow. Popper took this a step further and argued that science can never prove anything. A thousand experiments that produce the same results do not prove that the next experiment would end up the same. On the other hand, one observation is sufficient to disprove a hypothesis. If we say that the sun comes up every morning, and we observe that it does for years in a row, we have not proven that it will rise tomorrow. On the other hand, if the sun does not rise one morning, our hypothesis has been proven wrong.

The true goal of science, according to Popper, is to produce falsifiable hypotheses that it can test. There is a lot of benefit in this method, as it tends to prevent speculation about unprovable ideas; and scientists have largely adopted Popper's ideas. In graduate school, for instance, I took a course on statistics. We learned methods to demonstrate a statistically significant correlation between two things that we can't measure directly. We don't know, for example, how individuals vote, but we know the vote breakdown by precinct. By comparing vote counts across precincts with different characteristics, we could infer a correlation between how people vote and things like how much money they made or what race they were.

Only, we weren't allowed to draw direct conclusions. Because of Popper's ideas, we could only deny the reverse of our conclusion. For instance, we could not say that people tend to vote for candidates of their own race; we would have to say that "we reject the hypothesis that people do not vote for candidates of their own race disproportionately."

I didn't see the point of this exercise at the time, and I continue not to see it today. I actually agree with Hume and Popper that induction can never demonstrate logically conclusive physical laws; only abstract principles like mathematics can do that. The Pythagorean Theorem is true, and it will always be true in all cases, and I have absolutely no concern that anyone is going to prove it wrong. Newton's laws of motion, however, were only true up to a point, and Einstein demonstrated the point at which they cease to be true.

The problem is that I don't see the correlation between these cases. Science aims to produce the best possible model of the universe. While some scientists may believe that they arrive at essential truths, I think most would acknowledge that they can never apprehend the "thing in itself" (Ding-an-sich, a Kantian term for the ultimate nature of a thing). That doesn't matter; they are not producing logically infallible models, but models that correspond closely with observed behaviour. They've done a good enough job that I cross a bridge without worrying, usually, about whether it will collapse, and I fly without worrying that the principles of aerodynamics are actually different that what scientists say they are and the plane will suddenly plummet to the earth.

Moreover, I fail to see how reducing everything to falsifiability assists the process of scientific inquiry (besides encouraging people to make testable claims, as I indicated above). We may observe millions of sheep and find them all to be various shades of black, white, or grey, but never purple. Popper is correct that we could not therefore infallibly conclude that sheep are never purple, but would the existence of a single purple sheep disprove our hypothesis? Perhaps there is something wrong with our observation -- maybe we were drunk, or maybe we were viewing the sheep through purple glasses, or in a purple light. Or maybe someone dyed the sheep purple. That would indeed falsify the idea that no sheep are purple, but it wouldn't falsify the idea that no sheep are born purple.

The idea of falsification seems even more dubious in the case of statistical studies, such as the ones mentioned above. Falsification is an extremely rigorous standard; by it, you are only allowed to make statements that are tautological, to the extent that you know (assuming your observations to be correct) that you are rejecting a false claim because you have seen something that directly refutes it. It works if you want to prove everything with the same certainty as the Pythagorean theorem. Statistical methods, however, are exactly the wrong kind of approach to use if you want falsifiability. You can never demonstrate with apodictic certainty that a statistical correlation matches a real causal relationship; you can only demonstrate that it is very unlikely to be false. But if you are dealing in the realm of probabilities, why use a method designed to grant a priori certainty? A statistical correlation of voting patterns shows that some aspect of voters is likely influence how they vote, never a 100% chance that it does. Why not phrase this in the positive form rather than the negative? And the same logic can be extended to cases where statistics are only used inferentially: if I have seen a million sheep from all parts of the world, and I have never seen a purple one, I am on a statistically sound basis if I assert that sheep are not purple. I can't prove that no one will ever see a purple sheep, but that doesn't stop my observation from being scientifically useful.

Perhaps Popper took some account of these concerns -- I don't pretend to be an expert in his thought. There are just the things that make me doubt the dogma of falsification as a useful tool, and I really doubt whether most scientists actually think in terms of falsification rather than positive assertions.

Next time, I will consider the scientific views of one of Popper's opponents, Thomas Kuhn.

Tuesday, December 15, 2009

Ho, ho, ho

Christmas carols: love them or hate them, it's hard to avoid them this time of year. I like carols, but I tend to prefer the older ones. Not that I have anything against adding to the canon, but there is something a little...I don't know, empty...about songs like "Winter Wonderland" and "There's No Place Like Home For the Holidays." I don't apply that to "Frosty the Snowman" or "Rudolf the Red-nosed Reindeer," which strike just the right note for me.

My son is in his school's chorus, which means I've gotten to hear every Christmas song at each of his performances. One of the classics, a song I actually like, is "Up On the Rooftop." I like it, but I admit that I am puzzled by the refrain: "Ho, ho, ho, who wouldn't go?" Who wouldn't go where? Up on the rooftop? If that's what it means, it seems a weird question to ask. I think the composer just needed a rhyme there.


I found this cute photo at Supertremendous.com in a collection of ironic photographs. They are probably not "the 25 most ironic photos of all time," but some of them are pretty funny.

Thursday, December 3, 2009

One Hundred

When I began this blog about 6 months ago, I did not expect it would attract a large audience. My expectations have been fully met. The only exception came when Linkiest decided (at my request) to link to my blog post on liberal denial of media bias. That created a viewership spike that screwed up the graph on Google analytics, because it was totally off the scale.

In case some of those new viewers from Linkiest are still around, I figured the hundreth post would be a good time to highlight some of the most interesting previous blog entries. Here are my completely subjective choices:
  1. Etiology of a Medical Crisis
  2. The Nuclear Threat
  3. The Awful Truth
  4. Gates, Boxer, and Race
  5. Dumb Political Slogans
  6. Acorn Cracked
  7. Obama's Citizenship
  8. Peace of Westphalia Day
  9. Self-interest
  10. Environmental Pathos

Tuesday, December 1, 2009

Economics in One Lesson

No wonder people don't trust economists. When people tell you that cap-and-trade will lead to job growth, it doesn't fit common sense. Of course, a new government program on this magnitude will certainly create jobs, exactly as claimed: "research and development in new technologies, new factories to produce solar panels and wind turbines, and energy-efficiency retrofits of commercial and residential real estate." But the question is, will it be a net increase in jobs? Because even the authors of this article admit that "some businesses that rely on dirty energy will be hurt." (Why not all of them? Are some of them getting permits for free?)

Things get the most confusing when they involve money, because money is a very slippery subject. According to the article cited above, "almost all of the revenue from the permit auction is returned to the American public." Therefore, even though the authors admit that energy prices will rise, they assert that "the refund can make up and even exceed the additional expenses for most Americans." Is that true? If so, we can make our economy infinitely cleaner simply by returning the costs paid by business back to consumers. Why tolerate any pollution at all?

Of course it's not true, as most people will recognize intuitively. To see why, let's take money out of the equation. Let's take out jobs, too, while we're at it. Our economy's productivity is not based on how much money we have or how many jobs it creates. Banks can print money without adding any value, and we can create jobs -- temporarily, at least -- by downgrading technology. If we outlawed the transport of goods by motor vehicles, there would be an explosion of jobs for people to portage goods on their backs, but no one would think this was good for the economy.

No, our economy's productivity is based on the goods and services that we get out of it, regardless of nominal prices or labor inputs. And the one thing we can be sure of is that changing to cleaner energy sources will require more inputs per unit of electricity -- in other words, we will have to work harder to get the same amount of juice. A new Berkeley study admits as much, although Barbara Boxer touts it as evidence that clean energy is a jobs producer (scroll down to "Barbara Boxer's Good News"). The problem is that the additional people and resources devoted to producing electricity will not be available to produce other things, like televisions, health care, and blogs. That's something that even liberals would not be happy about.

This is not to say that mandating cleaner energy is necessarily bad; clean air and water provide health benefits as well as intangible advantages. But they also, always, require tradeoffs. It would be best if our politicians acknowledged the tradeoffs openly rather than pretending that we can improve the environment for free.

The title of this post comes from Henry Hazlitt's wonderful book, still popular after all these years. And if more politicians would read it, they would not keep making the same mistakes.