Truth and Value in Philosophy

(This post is not comp-related; it's just an attempt to crystallize something that I was thinking about today.)

Many philosophers (including me) tend to operate under the assumption that a claim has value only if it is true.  This assumption is propped up by a vague worry that the only way to deny it would be to adopt an unattractive view about truth, such as nihilism,  some kind of relativism, or an obscure post-modernism.

This worry is unwarranted.  The problem (or at least a problem) with the assumption that a claim has value only if it is true is not that there is no such thing as truth, or that truth is not absolute, or that truth is not an important desideratum; it is that truth is too high a standard to apply across the board to all intellectual endeavors.  Truth requires total precision, an absence of ambiguity, and complete fidelity to the facts.  It's difficult to think of any claims outside of logic and mathematics that meet this standard.

One might admit that truth is too high a standard, but deny that it is too high an aspiration.  That is: we should always aim for the truth, even if we can never reach it.

I agree that, within a particular inquiry, one should aim to be as faithful to the facts as possible, all else being equal.  However--and here's the point that I want to emphasize--one should not place such a high premium on truth that one neglects interesting and important approaches to interesting and important topics on the sole grounds that those approaches to those topics will not yield claims that are true, or even very nearly true.

Consider the account of the nature of science that Kuhn presents in The Structure of Scientific Revolutions.    Many critics have pointed out that many aspects of Kuhn's view are false.  Take, for instance, the claim (implicitly suggested if not explicitly stated in Kuhn's account) that any sufficiently mature field of science is governed by one dominant paradigm at any given time.  It would be easy to multiply examples of seemingly mature fields that contain multiple competing paradigms, and perhaps fields that don't seem to be governed by any very unified paradigms at all.

I don't claim that critics should not compare Kuhn's account of science to actual scientific practice and to point out disparities.  What I do claim is that one should not be too quick to move from the claim that Kuhn's account is false in many respects to the claim that Kuhn's account is not useful or valuable for understanding science.

Kuhn gave us is a highly original way to think about science.  That framework is imperfect in many ways.  If we take it too seriously, it can lead us astray.  But by giving us a new way to think about science, it allows us to notice things we would not otherwise have noticed and to draw connections we might not otherwise have drawn.  It may be that, even though Kuhn's account is false, we're better off with it than without it.

The same could be said about any number of ambitious projects, particularly in intellectual history.  Dewey's The Quest for Certainty and Collingwood's The Idea of Nature are good examples.  We philosophers tend not to read such works any more, and we (at least most of us) certainly don't attempt to write them.  One reason we shun such large-scale projects, I think, is that we realize that any picture we can paint with such broad strokes will inevitably misrepresent the complex, messy reality of the phenomena we wish to characterize.  What we say won't be true.  Moreover, counterexample-mongers will advance their careers by pointing out that what we say isn't true.

But maybe that's ok.  Maybe what we say doesn't have to be true to be illuminating.  Fidelity to the facts matters, but it doesn't matter so much that any significant departure from the facts completely vitiates a project; and it doesn't matter so much that we should only pursue projects for which near-perfect fidelity to the facts is an achievable goal.

Update on the Oil-Drop Apparatus

On Friday, Paolo and I are meeting with Jim Stango, Pitt's physics demonstrator, to borrow the Physics and Astronomy Department's miniaturized PASCO apparatus.  We'll take it to the HPS lab and start figuring out how to use it.  On February 14 we're planning to use it in a session of the Experimental HPS seminar Paolo is running this semester.

The plan at this point is to start with the miniaturized apparatus and then to use our experiences with it as the basis for a proposal to work with Millikan's original equipment.  At that point, we should be able to show pretty convincingly that we understand the experiment and that we have specific questions about it that working with the original apparatus can help us answer.  The biggest question will be whether the good folks at Cal Tech will be willing to let outsiders get their hands on a major piece of physics history.

The Original Millikan Apparatus

I think CalTech still has Millikan's original apparatus, and they still use it for demonstrations. It would be fantastic if there were some way I could get my hands on it for this project. The idea isn't incredibly far-fetched. I know that one researcher who was working on Goethe's optics got permission to redo Goethe's experiments using his original instruments, which were being held by a museum. The fact that they still use the apparatus for demonstrations shows that they aren't protecting it like a holy relic, and it's evidently a very sturdy piece of equipment. I could probably get at least partial funding for travel and living expenses from the Salmon fund. Being able to work with the original apparatus would elevate my history comp from potentially marginally interesting to very, very cool.

But, ok, it is a little far-fetched to think that all of the relevant factors would have to come together. First, I need to confirm that CalTech actually has the apparatus and that it is in working order with all of the necessary auxiliary parts available. Then I would have to get permission to work with it, which is not impossible but somewhat unlikely. After that, I would have to get sufficient funding to fly out to California and live there for, I would think, about a month. Finally, I would have to weigh the costs and benefits of either being away from or uprooting my family for a good chunk of the summer.

Still, it's worth looking into. I emailed Paolo about my suspicion that CalTech has the apparatus, and he seemed intrigued. My evidence that they have it comes from two videos online. The first is a brief demonstration using an apparatus that looks just like Millikan's:

The second is an old educational video that was filmed in the same lecture hall, in which the lecturer points to an identical-looking apparatus in roughly the same spot on the same table and says explicitly that it is Millikan's own apparatus (about 21:40 in):

Come to think of it, it might actually be better for me if they have a replica of Millikan's apparatus, rather than the original one. The original would have a nice "gee-whiz" factor, but they might be more willing to let a grad student tinker with a replica.

I suggested that Paolo contact Jeff Cady, the demonstrator in the first video, because he is more likely to be taken seriously than I am. We'll see what happens!

Overview of the Philosophy Comp Project

I would like to write my philosophy comp on a topic in the philosophy of statistics. My leading idea at the moment is to take a close look at some aspect of Deborah Mayo's error-statistical account of statistical inference. The philosophy of statistics (as well as statistics itself) is roughly divided into two camps: frequentist and Bayesian. (I'll ignore likelihoodists for now.) Among philosophers, Mayo is the de facto leader of the frequentist camp. My impression is that the division between the two camps is deep enough that not many people have taken a serious, critical look at Mayo’s work. Those in the frequentist camp already, by and large, agree with her; those in the Bayesian camp can’t be bothered; and people in the philosophy of science who aren’t firmly in either camp, like me, haven’t done much work on the topic.

Bayesian philosophers of science use Bayes’ theorem as the basis for a normative theory of scientific inference. Frequentists objections to this program generally focus on the use of prior probabilities. Frequentists claim that subjective prior probabilities are out of place in science, which they claim ought to be as objective as possible. Some frequentists go further and deny that we can even speak meaningfully about the probability (prior or posterior) of a hypothesis. Orthodox Bayesians, by contrast, interpret all probabilities as subjective degrees of belief, and claim that one cannot draw valid probabilistic inferences without taking prior probabilities into account.

One topic of ongoing debate between the two camps is the claim that frequentist hypothesis testing is subject to the base-rate fallacy. From what I've seen of the literature on this debate, it seems that Bayesians are guilty of a hit-and-run: they've raised the base-rate fallacy objection, but have not made much of an effort to understand and respond to frequentist rejoinders. Bayesians are free, of course, to focus on whatever problems they find most pressing; but someone ought to engage the frequentist position in a more serious way.

In subsequent posts, I will work through some of the central papers in this debate. Here’s my bibliography so far:

• Collin Howson (1997), “Error Probabilities in Error"
• Deborah Mayo (1997), “Error Statistics and Learning from Error: Making a Virtue of Necessity”
• Ronald Giere (1997), “Scientific Inference: Two Points of View”
• Collin Howson (2000), Hume’s Problem
• Peter Achinstein (2001), The Book of Evidence
• -- (2010), “Mill’s Sin’s or Mayo’s Errors?”
• Collin Howson and Peter Urbach (2005), Scientific Reasoning: The Bayesian Approach
• Deborah Mayo (2010) “Sins of the Epistemic Probabilist: Exchanges with Achinstein”
• Aris Spanos (2010), “Is Frequentist Testing Vulnerable to the Base-Rate Fallacy?”

Recreating the Oil-Drop Experiment

Creating a full-scale reproduction of Millikan's apparatus is not feasible on our budget. For now, at least, we will be using a commercially available PASCO apparatus intended for instructional use in undergraduate physics labs. We will be borrowing the PASCO apparatus from the Physics & Astronomy department, which apparently used to use it for undergraduate labs but no longer does.

The fact that we will be using a commercially available device raises at least two questions. First, why bother to recreate the experiment when thousands of undergrads have already done so? Second, won't differences between the PASCO device and Millikan's apparatus limit what we can learn from the re-production?

The answer to the first question is that we will be using the PASCO device to address questions that it is not used to address in undergraduate physics labs. We are not re-visiting Millikan's experiments because it would be fun to try to replicate his results; we are trying to gain insight into historical questions, such as questions about why Millikan handled his data the way that he did, by learning from firsthand experience what Millikan saw when he looked into the oil-drop chamber.

The answer to the second question is a bit more complicated. The PASCO apparatus is essentially a miniaturized version of Millikan's apparatus. All of the physics is there--including a source of ionization radiation--but some things will be different. For instance, one of the advantages of the larger size of Millikan's apparatus is that the metal plates across which a charge is placed more closely approximate the idealized infinite parallel-plate capacitor for a longer range of fall distances. As a result, Millikan's electric field was likely more uniform than ours will be. Another issue will be that the phenomena won't look quite the same in our experiment as they did in Millikan's. The inside walls of the oil drop chamber are made of a different material, the light source that illuminates the drops will be different, the viewing telescope will be different, and so on. In short, we will have to be cautious about extrapolating from what we see to what Millikan would have seen. Ideally, we would like to find textual support in Millikan's writings for any claims we make about what he would have seen based on what we see.

There are special video cameras that would allow us to record the experiment. We are hoping to take videos and post them online, as Paolo has done for his Galileo and Coulomb experiments (here). However, we do not yet know whether Physics & Astronomy has the right kind of camera and, if so, whether they would be willing to lend it to us.

The Oil-Drop Experiment

Here's a diagram of Millikan’s oil-drop apparatus. The main part of the apparatus is a big, hollow metal chamber, shown below:

An atomizer (“A” in the diagram) sprays oil drops into the chamber. Originally, Millikan used the atomizer from a perfume bottle (as in the photograph, I’m guessing), but over time he got fancier and starting using a pressure tank and passing the oil through glass wool before it got to the chamber, presumably to eliminate dust.

As the oil drops pass through the atomizer, they pick net electric charges due to friction, the same way that you and I pick up a net electric charge when we shuffle across the floor wearing wool socks. The charge oil drops then fall under the force of gravity until some of them pass through a small opening so that they are between the two metal plates labeled “M” and “N” in the diagram. Those plates are connected to a series of batteries. Those batteries set up an electric field across the plates. One can tweak the direction and magnitude of this electric field so that it exerts an upward force on a given drop that exactly balances the downward gravitational force on that drop. In this way, one can “capture” a drop and hold it suspended.

In an early version of the oil-drop experiment (actually, at that point it was a water-drop experiment), Millikan would simply balance the electric and gravitational forces on a drop until the drop became suspended, and then calculate the electric charge that the drop would have to have for the two forces to balance, based on an estimate of its mass. That procedure was a good start, but it wasn’t terribly precise and it didn’t allow for direct measurements of changes in charge on a single droplet, which would provide the most convincing evidence that electric charge comes in discrete multiples of a fundamental unit.

Millikan switched from water drops to oil drops because the latter evaporate much more slowly, allowing him to make a long series of observations on a single drop during which the mass of the drop remained essentially unchanged. After he had captured a drop, he would switch off the electric field and record the time it took for the drop to fall under an electric field alone. He would then switch on the electric field, with its magnitude adjusted so that it exerted an upward force of the drop that was stronger than the downward force of gravity. He would then record the time it took the drop to rise the same distance as before. From this data, he could calculate the charge on the drop.

Occasionally, during a series of observations an oil drop would pick up a positive or negative ion from the air around it, changing its charge. This change would manifest itself as a change in the speed of the drop during the rising phase of its movement. Millikan used a source of ionizing radiation to make these illuminating events more common. Sometimes a drop would pick up a charge in mid-rise, so that its speed changed suddenly and discretely while Millikan was watching it. Millikan says that it is particularly striking to see a rising drop suddenly stop moving—a phenomenon that the electron theory can explain easily as being due to a drop with one unit of charge picking up a unit charge of the opposite sign. One reason to re-do the experiment is to see these changes in the speed of a drop during its rising phase. Are they really as striking as Millikan says, or is he dramatizing the experiment for rhetorical effect?

Previous experiments had suggested that the fundamental unit of charge, if there is one, has a charge in the vicinity 3 x 10^-10 e.s.u. Thus, if there is such a fundamental unit, Millikan should find two things:

• First, all of his calculations of the total charge on a drop should yield values that are (approximately) integral multiples of a single number on the order of 10^-10 e.s.u.
• Second, the calculated changes in charge should occur in small integral multiples of the same number.

For the data Millikan reported, these conditions were satisfied beautifully. A few of his runs were anomalous, however, as I will explain in future posts. Millikan calculated a value of 4.774 +/- 0.009 x 10^-10 e.s.u. for the elementary electric charge, which is slightly smaller than a recent value of 4.80320420 +/- 0.00000019 e.s.u. (The discrepancy is due primarily to the fact that Millikan used an incorrect value for the viscosity of air.)

Next post: How we will re-create Millikan's experiment.

Overview of the History Comp Project

’ve worried more about the history comp than I have about the philosophy comp, because I’m primarily a philosopher by disposition and by training. However, I think I have a pretty good start on this one.

My history comp project is a piece of experimental HPS, which involves revisiting past experiments in order to address historical, philosophical, and scientific questions. I am working with Paolo Palmieri, a professor in my department, who has been a pioneer in this field. Most of his experimental HPS work has been on Galileo’s pendulum and inclined-plane experiments. There have been debates among Galileo scholars about whether Galileo actually performed certain of the experiments he reports, or whether they were merely thought experiments. Or perhaps they were somewhere in between: maybe he rolled balls down inclined planes, but he didn’t measure the times of fall precisely enough really to demonstrate the results he claims. Historical reconstructions of Galileo’s experiments can contribute to this debate by, for instance, providing evidence that he could or could not have gotten certain kinds of results using the materials and methods that were available to him.

I am planning to take an experimental HPS approach to Robert Millikan’s oil-drop experiments. These experiments—performed primarily between 1909 and 1912—convinced nearly all physicists that electricity comes in discrete units and provided the most precise measurement of the elementary unit of charge that had ever been performed.

Millikan published his first definitive paper with results from the oil drop technique in 1913. In 1923, he won the Nobel Prize for these experiments and his work on the photoelectric effect. One reason it took ten years for him to win the Nobel was that his work was challenged by Felix Ehrenhaft, a Viennese physicist who claimed to find evidence in experiments similar to Millikan’s for “subelectrons,” units of charge smaller than Millikan’s supposedly fundamental units. Millikan argued that Ehrenhaft was generating artifacts by using bits of metal and other materials that, Millikan claimed, could not have spherical, unlike Millikan’s oil drops. Ehrenhaft argued that his materials were in fact spherical, and that Millikan begged the question in favor of the existence of a fundamental unit of charge in the way he analyzed his data. Millikan published his last, rather cranky paper on this debate in 1925, while Ehrenhaft continued to argue his case into the 1940s. By that time the mainstream physics community had accepted Millikan’s results and rejected Ehrenhaft. Ehrenhaft did not help his cause by claiming to have created other anomalous effects, such as magnetic monopoles and magnetolysis.

Although Millikan won the day, questions remain about what Ehrenhaft was observing that made him think that he had found subelectrons and about why the physics community chose to accept Millikan’s results and reject Ehrenhaft’s. These questions became more complicated and more pressing in the 1960s, when historian Gerald Holton reviewed Millikan’s laboratory notebooks from the experiments that made it into his 1913 paper. He found that Millikan selectively excluded some of his experimental results from publication. Holton argues that Millikan was just doing what all good experimentalists do—making reasoned judgments about which results were reliable and which were unreliable. However, the results he threw out included a small number of runs that seemed fine except for the fact that they would have seemed to support Ehrenhaft’s subelectron hypothesis. Moreover, Millikan did not just fail to report that he discarded anomalous results; he says explicitly says that he did not do so: “It is to be remarked, too, that this is not a selected group of drops but represents all of the drops experimented upon during 60 consecutive days” (Millikan 1913, 138). It is hard to interpret these words in a way that doesn’t make Millikan out to be a liar. Daniel Goodstein has tried, but I’ve yet to understand his explanation.

There is a fairly large literature on the Millikan-Ehrenhaft dispute and on the issue of Millikan’s alleged fraud. I aim to contribute to this literature with insights derived from working with a scaled-down version of Millikan’s apparatus. (I also have high-quality scans of Millikan’s laboratory notebooks that I have begun to examine.) It is hard to know in advance what these insights will be, but I have a few guesses. First, I want to compare the phenomenology of the experiment to Millikan’s remarks on it. Millikan speaks as if the experiment essentially speaks for itself. “One who has seen this experiment,” he says, “has SEEN the electron.” I’ll be interested to find out whether doing the experiment feels like seeing the electron. I’ll explain in a forthcoming post what the experiment involves and why I think it might feel this way. If it does, then it would be a plausible conjecture that the experience of doing the experiment played a major role in convincing Millikan that the theory of a fundamental unit of charge was correct—perhaps to the point that he saw the data as a tool for displaying the correctness of the theory, rather than as the primary epistemic basis on which the theory should rest. I think there is some textual support for this conjecture, but it would be greatly strengthened if the experience of doing the experiment turns out to be rather striking. If the experience of doing the experiment bears out this conjecture, then it would, I think, give some grounds for being a bit more lenient regarding Millikan’s data manipulation than we might otherwise be. Why report data that seemed to speak against the electron hypothesis when he had SEEN the electron, and thus knew that it was real?

Second, it would be quite interesting if we could reproduce anomalous observations akin to some of those the results from which Millikan discarded. For instance, Millikan says at a couple points in the notebook that a drop “flickers” as though “unsymmetrical in shape.” (He threw out the results from those drops.) What do such drops look like? Is the flickering obvious? Do the flickering drops seem different from the oil drops in other ways? Can we make any reasonable conjectures about what the flickering drops are, e.g. specks of dust or multiple drops stuck together? It would be even more interesting, if we could do it, to run the experiment using some of the materials Ehrenhaft used. Would we get the same anomalous results? Is there any way we could use modern tools to investigate whether these materials were in fact spherical or not? Could we use computer simulations to investigate how departures from sphericality should affect the results?

In the long run, it would be fantastic to do a plausible re-creation of some of Ehrenhaft’s experiments. Trying to explain Ehrenhaft’s results is the kind of project that one would like HPS scholars to pursue—a side-trail in the history of science that’s quite interesting and unresolved, but that working scientists don’t have time for. However, the practical obstacles are daunting. Ehrenhaft’s apparatus was more complicated than Millikan’s and, as I’ll explain in the next post, we’re not even doing a full-fledged re-creation of Millikan’s. I’ll see how this relatively easy Millikan re-creation goes, and then perhaps think about a more ambitious project on Ehrenhaft.

Hey look, I’m already at over 1,000 words—1/7 of the way to my history comp! I’ll be done in a week. Or not.