Theory vs. observation

I wrote the following for another context, but I think it might be of interest here.

What it's all about is a debate between people with two different views of how the scientific process operates. One group claims that science is based, first, on careful observation of the world, followed by construction of a theory to account for the data. The other group claims that theories and hypotheses are constructed first, followed by collection of data to provide evidence or refutation for the theory or hypothesis.

My opinion's different from that of either group...

Science relies on both observation and theory. Neither alone is sufficient, but the mixture that any particular science or scientist uses can vary a lot from case to case. Kind of like blind men describing the elephant.

It's an iterative process. Scientists use theory to guide observation, and observation to guide theory. In working on any particular problem, one can enter at different phases of the process. Sometimes one starts with puzzling observations in need of a better theory. (Quote: "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...'" -- Isaac Asimov) And sometimes one starts with theoretical ideas in need of observational support.

Which comes first, theory or observation? That's a less important question than may be apparent. As noted, any particular individual enters the process at a specific point, which may more heavily involve theory or observation. In either case, it's always (nowadays) true that every investigator is standing "on the shoulders of giants". (A large topic in itself. The metaphor, supposedly, is due to Newton. Famous book on the subject by Robert K. Merton. Basic idea: there are antecedents to everything, including the metaphor.)

But which is the absolute first? Sure, it has to be observation, but only in a somewhat trivial sense, in that all "knowledge" ultimately comes in through the physical senses. Or you could say that it's "only a theory" that your observations have a direct relationship to reality. Now we're in the territory of epistemology, which is generally not the concern of working scientists.

However, when one is thinking about the philosophy of science, one has to take into account the idea that theory determines what can be observed, and in fact what the "meaning" of observations can be. This leads into the realm of Thomas Kuhn and "paradigms" that control what is observed and how it is interpreted. This can be, and has been, taken to the extreme relativist position that science is meaningful only in terms of somewhat arbitrary cultural constructs. Almost all working scientists, of course, think that's going way too far.

Nevertheless, there are plenty of cases where theory has run far ahead of observation. Example just in physics include quantum mechanics, the big bang theory, cosmic inflation, and black holes. Indeed, the gold standard of theory is to make correct predictions of observations that have NOT already been made. A theory that merely accommodates existing observations is suspect of being fudged to fit the facts. Yet that's the right way to go in some cases, where the theory has "free parameters", like the Standard Model of particle physics. (Physicists still want to find a theory that predicts the parameters, and that goal remains quite elusive.) Climate models are the same way. They are adjusted to fit what has been observed in the past, with the hope that forward predictions will also be correct.

And that brings us back to relativity, in the Einsteinian, not cultural, sense (which have very little to do with each other).

The foundation of special relativity is Einstein's rather unorthodox (at the time) idea that the speed of light is the same in all reference frames. If one takes that to be axiomatic, then some quite surprising consequences inevitably follow, such as the equivalence of mass and energy (E=mc²). Nobody was expecting that, or had any observations to even suggest it. Two of Einstein's (five) amazing papers of 1905 resulted from following the axiom to its logical conclusion.

Now, one might think that the Michelson-Morley experiment of 1887 gave the observational basis for Einstein's special theory. But the evidence for this is very unclear. Einstein himself was quite vague about the issue. Pais' biography devotes more than 10 pages to the topic. One thing is clear: Einstein didn't cite the experiment in his 1905 paper, even though it would have bolstered his case. But at various times he acknowledged having been aware of it in 1905. In any event, the experiment doesn't seem to have been anything like the key motivation for special relativity.

General relativity (1916) is an even more interesting case. One of the foundations of GR was special relativity, of course. Another key insight was Einstein's "equivalence principle", which posited that the behavior of a moving object in a gravitational field was the same as the observed behavior of the object in a reference frame that is accelerating with respect to the object.

Again, Einstein took theoretical principles as axioms. He worked for about 10 years to figure out what the consequences had to be. While some observation obviously supported his principles, there was no other observational input after making them axioms. Interestingly, Einstein was not a strong mathematician, which may be why it took him 10 years after 1905 to come up with GR. He had to rely on a friend, Marcel Grossman, who was much better at math. (Of course, what they needed was very cutting edge math at the time.) Einstein also obtained the help of other eminent mathematicians, like Tullio Levi-Civita.

Out of this collaboration emerged the theoretical idea that gravity should not be regarded as a traditional Newtonian force, but instead as a phenomenon due to curvature of space itself. There was nothing particularly observational about this idea. It was simply a beautiful theoretical idea. Indeed, people still have a tough time conceptualizing what it means for space to be curved. Just as people have a hard time conceptualizing the 4 dimensions of spacetime. These kinds of ideas simply do NOT come out of everyday observation.

The story gets even better. Einstein and his collaborators decided that the right equation to describe gravity should have certain very technical, theoretical properties. The equation had to have a "covariant tensor" form. It should describe the geometry of space in terms of a mathematical construct called a "metric". And in the boundary case where no gravitational mass is present, the metric should be, specifically, the "Lorentz metric" used for spacetime in special relativity. From these theoretical considerations, rather than from any specific observations, the collaborators came up with a tensor equation, which is the essential part of GR.

From that equation it was possible to predict that light has to bend in the presence of (large) masses. Nobody had ever observed that, or even suspected it. Not only was the fact of bending correct, but the equation even correctly predicted the amount of bending. This is why Eddington's measurement in 1919 of the bending of light during a solar eclipse caused quite a sensation, including headlines in the NYT. It's part of the reason Einstein acquired his "genius" reputation. (Few ordinary people knew anything about the 1905 papers.)

And the story goes on. Einstein was, in fact, misled by observations to modify his GR equation. He inserted into it what he called a "cosmological constant", so that the equation would predict what observations at the time (around 1920) seemed to indicate - namely that the universe was not collapsing under the force of gravity, but appeared to be static. At times, it is actually better to rely on theory than observation.

Subsequent observations by Hubble (later 1920s) indicated that the universe was in fact expanding. (Even those observations turned out to be quite inaccurate, though qualitatively correct.) So Einstein tossed out the cosmological constant in disgust. That was (apparently) a mistake, as in 1997 new observations indicated that the universe was not only expanding, but actually doing so at an accelerated rate. The cosmological constant - if chosen correctly - in fact predicts that.

Now, the actual value of the constant does depend on observations. It has to have the value that gives the correct amount of observed acceleration. All attempts to use theory to compute this value a priori have been miserable failures... so far.

And that view of the cosmological constant depends on other theoretical assumptions (such as the near perfect flatness of spacetime due to inflation) which have conceptual appeal, but (at least until fairly recently) little independent observational support. Indeed, much of modern cosmology itself depends largely on theoretical assumptions (isotropy and homogeneity) that observationally are only approximations, and could be substantially wrong.

Bottom line: theory and observation in the scientific process cannot be separated. It's kind of like trying to imagine one hand clapping.

Tags: relativity, scientific method

No more business as usual

A million thanks to SusanG at Daily Kos for mentioning this:

Obama's Victory: A Consumer-Citizen Revolt

As recently as this summer, while the economy unraveled (BusinessWeek, 7/14/08), I made two trips to Silicon Valley in the hopes of finding leaders who grasped the crisis—and the opportunity—inherent in the destruction of trust. I listened to Facebook executives but found them obsessed with how to monetize the site with advertising. Their users were not individuals, but "eyeballs." I asked Google (GOOG) CEO Eric Schmidt how he would develop and sustain the trust of his users. His response was to cite the provision of two classes of stock intended to insulate top management from investor pressures. I gave a talk on the crisis of trust. The response from self-described Internet court jester Esther Dyson was typical of what I had been hearing: "Personally, I'm not that concerned if people don't trust large institutions."

A few weeks later economic panic gripped the stock market. I flipped on ABC's Sunday morning news show with George Stephanopoulos only to hear economist Larry Summers explaining that the surprising depth of the economic meltdown was due to the loss of trust in institutions. What he didn't say was that this loss of trust is a vast sea whose level has been rising for decades. The subprime debacle and the ensuing credit freeze simply marked the moment when the sea wall was finally breached. ...

So can we invent a business model in which advocacy, support, authenticity, trust, relationship, and profit are linked? Can I write that sentence without invoking fear, disbelief, cynicism, or peals of laughter? The ugly practices that killed trust seem intractable to most people, whether they are the ones trapped inside the money machine or on the receiving end of its operations. But after this election, the answer to these questions has irreversibly changed. The answer today would have to be not only "yes we can" but also "yes we must."

No, this is not about "science" per se, unless one considers the philosophical side of economics (rather than the quantitative side) to be a science. Rather, it is the simple observation that anyone reading the daily news with an open mind can understand: Basing a modern large-scale economy primarily on the evolutionarily ancient motivation of greed and personal self-interest is not working out very well...

Moral choice: fairness, utility, and the insula

We continue to learn more about the neuropsychological basis of moral thinking and moral emotions in humans:

Justice In The Brain: Equity And Efficiency Are Encoded Differently (5/8/08)

Which is better, giving more food to a few hungry people or letting some food go to waste so that everyone gets a share" A study appearing in Science finds that most people choose the latter, and that the brain responds in unique ways to inefficiency and inequity.

The study, by researchers at the University of Illinois and the California Institute of Technology, used functional magnetic resonance imaging (fMRI) to scan the brains of people making a series of tough decisions about how to allocate donations to children in a Ugandan orphanage.

There are two main issues regarding moral decision making here.

The first involves two separate principles often used in analyzing moral/ethical problems related to the distribution of goods within a group of people. (The group might be children in a family or different classes of people in a society, among many possibilities.) On one hand, it is generally regarded as "good" to maximize "equity" in moral decisions, so that some individuals are not favored over others without significant justification. (I prefer the term "fairness" for this.)

On the other hand, it is also regarded as "good" to maximize "efficiency", so that the greatest total amount of benefit accrues to a group as a whole. (I prefer the term "utility" for this.)

But these principles can come into conflict, and the research discussed here investigates a contrived, but sharp, example. Philosophers of ethics call such dilemmas the problem of "distributive justice".

The second issue concerns the style of thinking that a decision maker faced with this kind of dilemma does use, and also, perhaps, what style the decision maker "should" use. On one hand, the decider might try to systematically and logically apply some standard set of rules that are considered appropriate for the situation. But on the other hand, the decider might rely more on emotional factors that indicate what "feels right", the "gut feeling", about what seems "right" in a concrete situation.

Philosophers often describe these two alternatives as "cognitivist" vs. "sentimentalist". The former is sometimes associated with the philosopher Immanuel Kant, and the latter with David Hume.

What emerges from the research is (not surprisingly) that individual decision makers differ in the degree that they favor "equity" vs. "efficiency", and also whether they tend to rely more on logic or emotion to make their decisions.

More interestingly, most people normally process considerations of both equity and efficiency in order to reach a decision, but different parts of the brain are used for the two. Likewise, in making the decision, distinct parts of the brain which normally handle emotional or logical processing can become involved in processing the equity/efficiency trade-off.

One way to think of this is that there are separate calculations of both equity and efficiency that are made for each available choice. And then the result of those calculations are fed to separate subsystems to weigh the alternatives.

The different moral and ethical decisions that different people will arrive at can be attributed to individual differences as to how the various stages of the decision process are handled. For instance, an individual may favor equity over efficiency, and tend to use emotion rather than logic to reach the decision.

Here's what the study found:

In these trails, subjects overwhelmingly chose to preserve equity at the expense of efficiency, Hsu said. "They were all quite inequity averse." The findings support other studies that show that most people are fairly intolerant of inequity.

The animation, in conjunction with the fMRI, allowed the researchers to view activity in the brain at critical moments in the decision-making process. After analyzing the data, they found that different brain regions -- the insula, putamen and caudate -- were activated differently, and at different points in the process, Hsu said.

Activation of the insula varied from trial to trial in relation to changes in equity, while activity in the putamen corresponded to changes in efficiency, he said.

In contrast, the caudate appeared to integrate both equity and efficiency once a decision was made.

The role of the insula (or, more formally, insular cortex) is especially interesting, since this brain region has been associated with quite a few other types of social-emotional mental processing. We'll come back to that in a moment. But here are the conclusions of the researchers:

The involvement of the insula appears to support the notion that emotion plays a role in a person's attitude towards inequity, Hsu said.

The insula is known to play a key role in the awareness of bodily states and emotions. Studies have shown that it is activated in people experiencing hunger or drug-related cravings, and in those feeling intense emotions such as anger, fear, disgust or happiness. Other research has implicated the insula in mediating fairness. ...

Together, the results "show how the brain encodes two considerations central to the distributive justice calculus and shed light on the cognitivist/sentimentalist debate regarding the psychological underpinnings of distributive justice," the authors wrote.

Here's how another report about this research summed it up:

Your Brain on Ethics (5/8/08)

The fMRI scans contain hints of how these two factors might be encoded by the brain. The insula, a brain region linked to processing emotion, became more active when subjects considered more inequitable distributions of meals; it was also more active in subjects whose choices suggested a greater-than-average aversion to inequity. Activity in another region, the putamen, seemed to track the common good, rising in proportion to the total number of meals that could be donated in a given case.

Now let's have a quick overview of the insula. Turns out that it's involved in a lot more than just moral decision-making. Here's a general article from a bit over a year ago:

A Small Part of the Brain, and Its Profound Effects (2/6/07)

According to neuroscientists who study it, the insula is a long-neglected brain region that has emerged as crucial to understanding what it feels like to be human.

They say it is the wellspring of social emotions, things like lust and disgust, pride and humiliation, guilt and atonement. It helps give rise to moral intuition, empathy and the capacity to respond emotionally to music. ...

If it does everything, what exactly is it that it does?

For example, the insula “lights up” in brain scans when people crave drugs, feel pain, anticipate pain, empathize with others, listen to jokes, see disgust on someone’s face, are shunned in a social settings, listen to music, decide not to buy an item, see someone cheat and decide to punish them, and determine degrees of preference while eating chocolate.

Damage to the insula can lead to apathy, loss of libido and an inability to tell fresh food from rotten. ...

Of course, like every important brain structure, the insula — there are actually two, one on each side of the brain — does not act alone. It is part of multiple circuits.

The insula itself is a sort of receiving zone that reads the physiological state of the entire body and then generates subjective feelings that can bring about actions, like eating, that keep the body in a state of internal balance. Information from the insula is relayed to other brain structures that appear to be involved in decision making, especially the anterior cingulate and prefrontal cortices.

Stay tuned. We'll be discussing the insula quite a bit more here, I think.

Further reading:

The Right and the Good: Distributive Justice and Neural Encoding of Equity and Efficiency – Original research report published 5/8/08 at Science Express (sub. rqd. for full access)

Which Orphans Do You Want to Starve? – Blog article by Sharon Begley at Newsweek

How Fairness Is Wired In The Brain – 5/28/08 press release about the research dealing with fairness and the insula

Tags: morality, fairness, utility, neuroscience, neurobiology, insula, insular cortex