TTYtter

After I started using Tweetie as my Twitter client on my Macbook, I began hankering for a Twitter client for my desktop at work that could thread conversations like Tweetie did (together with other more common functionalities like tracking hashtags, direct messaging, search, retweeting, URL shortening, and many others). But most of the feature-rich Twitter clients that are compatible with Linux seemed to be based on Adobe AIR, which is quite a chore to install on 64-bit Linux. After some painstaking reading through feature lists, I found TTYtter, which runs from the command line and had all the features I wanted. Lightweight with simple commands without (unlike other command line scripts like BLT) sacrificing functionality.

Explanation and Statistical Mechanics

Found a draft paper/chapter/talk of David Albert’s somewhere on the internet, titled Physics and Chance (PDF). The main purpose of the paper is to argue that the probability distribution that “we have from Boltzmann and Gibbs, or something like it,” is true. And he wants to argue that it is true and not just a useful instrument for the purpose of predicting the values of particular parameters.

Albert uses David Lewis’ account of laws of nature to argue for the truth of the probability distribution. The Lewisian view is that the laws of nature are those true statements about the world that have the best combination of simplicity and informativeness. Albert argues that not only does Boltzmannian statistical mechanics satisfy this requirement, but also that the laws of the special sciences are not laws of nature. He thinks the only laws of nature are the fundamental laws of physics that give us the microdynamics of systems, plus Boltzmannian statistical mechanics, plus the Past Hypothesis. (I will lump Boltzmannian and Gibbsian statistical mechanics together for now, as Albert does.)

Albert first makes a case for the necessity of statistical mechanics when we want to predict which macrostates follow from which macrostates. This makes a prima facie case for statistical mechanics being an informative addition to the fundamental microdynamical laws. But this sort of informativeness, one based on macrostates, and specifically on macrostates that are amenable to human observation (we don’t know yet that stat mech would work for other types of macrostates, if they exist), seems thoroughly instrumental. (Perhaps informativeness itself is an inherently instrumental property — I’ll leave that as an open question.) So, if this type of informativeness, informativeness about macrostates, is the main support for statistical mechanics being part of the laws of nature, it’s not clear how Albert establishes the truth rather than the instrumental value of statistical mechanics.

My objection aside, Albert anticipates that objections to his view will arise from those who see laws in the special sciences as being explanatory independent of the laws of physics. He examines Philip Kitcher’s argument that Arbuthnot’s regularity, which was a constant preponderance of births of males over females in London, is explained not by microphysical principles but by R. A. Fisher’s argument from parental expenditure. Kitcher writes that the microphysical account “would not show that Arbuthnot’s regularity was anything more than a gigantic coincidence”. Albert pounces on the word “coincidence” and says that that’s where statistical mechanics has to come in. He says that it is only by reference to the statistical mechanical probability distribution that Kitcher’s talk of “coincidence” makes any sense.

On its face, this claim is utterly batty. After all, Arbuthnot did not consult the SM probability distribution before regarding it as a coincidence. He thought it was a coincidence from the point of view of a model that assumed sex determination worked like a “two-sided die”. Whether he was justified in using that model is beside the point. What’s important is that Arbuthnot, and the myriad other researchers in the special sciences who tried to explain away regularities, did not determine the coincidental character of those regularities by doing statistical mechanical calculations.

Albert admits this. He admits that we don’t explicitly consult statistical mechanics to decide if certain large-scale regularities we observe are coincidental. His only reply is that our lack of consultation isn’t any evidence against the existence of the SM probability distribution. Fine. But surely the burden of proof is on Albert here, to show how the distribution is relevant to the special sciences when the special sciences evidently carry on working, with reasonable success, without (usually) referring to statistical mechanics.

To be fair, Albert does have some sort of positive account of how it may be that the SM probability distribution grounds our identification of coincidences in the special sciences. He claims that if he were right that the laws of nature are just the microphysical laws and statistical mechanics, then some foggy, unconscious acquaintance with that probability distribution would have been hard-wired into organisms by natural selection.

This is highly implausible to me. Natural selection favours (among other things) characteristics instrumental to the survival of the organism. And as far as day-to-day survival is concerned, it seems far more useful, and far easier from a neural architecture point of view, to hard-wire the regularities of the special sciences directly into the brain, instead of hard-wiring some vague acquaintance with SM and expecting the brain to propagate those probabilities all the way up to make predictions about complex systems. It is also probably easier to simply hard-wire an ability to learn large-scale regularities.

In any case, the more problematic issue is that Albert’s attempt at a positive argument for the relevance of SM probabilities to special science explanations is made by asking us to assume first that he is right about the completeness of microphysics + stat mech. But that’s exactly what people like Kitcher are questioning when they bring up the independence of the laws of the special sciences.

The folk reductionism gets worse. Albert argues that his proposed package of the complete laws of nature explains macroscale happenings like the descent of man and Arbuthnot’s regularity, because if you started with his pet Past Hypothesis, with the uniform probability distribution over the microstates compatible with that, and propagated the probabilities forward in time according to classical statistical mechanics, you’d find that the descent of man and Arbuthnot’s regularity come out as highly probable events:

it is precisely because the account of the descent of man by random mutation and natural selection involves vastly fewer and more minor and less improbable such coincidences than any of the imaginable others that it strikes us as the best and most plausible explanation of that descent we have.

(I’ve left out Albert’s trademark emphases to avoid annoying readers.)

There are similar claims like this throughout the paper. At other points he claims that statistical mechanics also explains why large objects in our world do not spontaneously disintegrate into statuettes of the British royal family, because if we take the Past Hypothesis plus initial uniform probability distribution blah blah, we will find that the probability of large objects disintegrating thus is very low.

My problem with those claims is that there is no evidence whatsoever that if you indeed take the Past Hypothesis, put a uniform probability distribution on the initial states of the universe compatible with that, and evolve that thing forward in time, you’d really find that the descent of man, the longevity of macroscopic objects, etc. come out as highly probable events. Albert is asking us to accept these claims on faith, since we can’t make any serious attempt at those calculations. But if one is sceptical about the truth of traditional statistical mechanics in the first place, then one is hardly going to accept on faith the claim that it will indeed give the probabilities Albert wants for those macroscopic events.

So Albert’s attempt to subsume the special sciences to statistical mechanics is extremely weak. The implicit request for us to put our faith in SM is a more general problem that recurs throughout the paper. As mentioned earlier, Albert argues that we need stat mech to make the correct macroscopic predictions; to get correlations of the macroscopic properties of one event with those of a later event. In this way, stat mech is more informative than microdynamics alone, and thus should be considered a Lewisian law of nature. But part of his way of showing that we need stat mech to make the correct macroscopic predictions is to say that without stat mech, we would have no reason not to predict that any given stone won’t spontaneously distintegrate into statuettes of some royal family. Merely to get things right about the ordinary rigid objects of Newtonian physics, of the “projectiles and levers and pulleys and tops”, he says, we need SM, because otherwise how can we assume that these rigid objects can even remain intact while we apply Newtonian mechanics to them?

But the thing is, the medium-term integrity of pulleys and levers would hardly seem like something that has to be explained away except in the light of statistical mechanics. If someone hasn’t already accepted the whole spiel about how intact pulleys are “improbable” because the phase space of microstates of disintegrated pulleys is so much larger than that of non-disintegrated pulleys, why should he take the intactness of large-scale objects to be something that begs to be explained away? The explanatory need that SM is supposed to fulfill wouldn’t even exist unless you already accept [that version of] SM. Again, Albert doesn’t provide an argument that would engage someone who is skeptical of the predictive accuracy of a statistical mechanics that involves starting with the Past Hypothesis, putting a uniform over the microstates of the universe consistent with that, and so on.

Finally, I just don’t see how Fisher’s principle regarding sex ratios, and other principles of the special sciences, would not also qualify as laws of nature. Why would one regard the Past Hypothesis + microdynamics + statistical mechanics as more informative than microdynamics + principles of special sciences? Sure, there are many, many such principles, so one sacrifices simplicity, but one also gains a lot in informativeness. For there is no evidence whatsoever that Albert’s proposal for the laws of nature is more informative than the “dappled” proposal with its myriad special science “laws”. If anything, the latter has been shown to be informative, while we can never determine if the former is informative, due to computational difficulties freely admitted by Albert. And isn’t it also rather implausible that some probability distribution on the initial state of the universe in fact explains why, say, zebras have stripes?

Intrinsic duplicates and their conscious lives

This is a tangential thought from way back, that I’d been procrastinating on converting from scrawl to proper prose. (It’s still untidy, but I’ve figured that if I’m going to post it only when it’s been tidied, then it’ll never be posted.) It concerns an argument in Brian Weatherson’s ‘Are Humeans Out of Their Minds?‘. Weatherson is mainly responding to an argument by John Hawthorne about whether causation is extrinsic. My concern, though, is not with his main response, but with his argument against one of Hawthorne’s claims, a secondary issue in the paper.

Hawthorne’s claim is:

An intrinsic duplicate of any region wholly containing me will contain a being with my conscious life.

Seems plausible enough. But Weatherson argues that the following example of what he calls totality qualia undermines the intuitive case for Hawthorne’s claim:

Tweedledee is facing a perfectly symmetrical scene. His visual field is symmetric, with two gentle mountains rising to his left and his right and a symmetric plain in between them. All he can hear are two birds singing in perfect harmony, one behind his left ear and one behind his right ear. The smells of the field seem to envelope him rather than coming from any particular direction. There is a cool breeze blowing directly on his face. It’s a rather pleasant scene, and the overwhelming feeling is one of symmetry.

Tweedledum is very much like Tweedledee. Indeed, Tweedledum contains a duplicate of Tweedledee as a proper part. But Tweedledum also has some sensors in his skin, and brain cells in what corresponds to a suspiciously empty part of Tweedledee’s brain, that allow him to detect, and feel, where the magnetic fields are in the vicinity. And sadly, though Tweedledum is facing a duplicate of the scene facing Tweedledee, there is a major disturbance in the magnetic field just to Tweedledum’s left. This produces a jarring sensation in Tweedledum’s left side. As a consequence, Tweedledum does not share Tweedledee’s feeling of symmetry.

Whether a picture is symmetric is a property of its internal features, but it is also a feature that can be destroyed without changing the internal features by just adding more material to one side. It is a totality property of pictures, a property the picture has because it stops just where it does. Similarly, totality qualia are qualia that we have in part because we don’t have any more feelings than we actually do. Feelings of symmetry are totality qualia in this sense, as are many of the feelings of calm and peacefulness associated with Tweedledee’s state. It is not intuitive that totality qualia should be intrinsic to a region. Indeed, it seems intuitive that a duplicate of me that was extended to produce more sensory features would lack these feelings. Hence a duplicate of me would not share my conscious life in all respects, so Hawthorne’s [claim] is also false.

Note that that final sentence quoted contains an invalid inference. Hawthorne’s claim is that a region that is a duplicate of a region containing you would contain at least one being that has your conscious life. It’s quite possible that it also contains beings that do not share your conscious life. So the mere fact that a duplicate of you would not share your conscious life under some conditions does not undermine Hawthorne’s claim.

In other words, we shouldn’t be talking about the conscious lives of duplicates of you, specifically. We should be talking about duplicates of regions containing you, and the conscious lives that these duplicated regions contain. In the final paragraph quoted, Weatherson seems to be arguing against the claim that any duplicate of me will itself share my conscious life in all respects. But this is different from the claim that any duplicate of a region containing me will contain a being that shares my conscious life.

Once we see that Hawthorne’s claim deals with duplicating regions and not just the being itself, we can see that totality qualia don’t have the implications Weatherson thinks they do. Because if we are duplicating a region that contains the being minus the region containing the sensors that cause totality qualia, then the duplicate itself is also going to be a region containing the being but not the relevant sensors, and hence the being in that region would have the same totality qualia as its duplicate. If, on the other hand, we are duplicating a region that contains the being and the region containing the symmetry-upsetting sensors, then the duplicate will also contain the being and the sensors. Once again the conscious life of the being is duplicated.

Put another way, in order to check Hawthorne’s claim, it doesn’t do, as Weatherson does, to have one region containing the being but without the sensors, and then duplicate just the being-without-sensors, and put this duplicate into a region containing sensors. The larger region-with-sensors isn’t a duplicate of the first region, so it’s not relevant to Hawthorne’s claim. On the other hand, if we try to dodge this by taking the region to be duplicated to be just the being-without-sensors, then when we duplicate said region, all we’d get is a region containing a being-without-sensors. Which corroborates Hawthorne’s claim.

Suppose we take the latter course — our duplicated region is just the region that consists of the being-without-sensors, and nothing else (I think this is the duplication that Weatherson wants us to imagine, in his argument). Weatherson could then say that that region containing a being-without-sensors could be embedded in a world that has, in fact, sensors at the requisite locations. That world would then contain a being whose sensation of symmetry is upset.

That’s for the world in which the region-without-sensors is embedded. But for the purposes of evaluating Hawthorne’s claim, we want to know if the region-without-sensors contains a being with an upset sense of symmetry, since that’s the region being duplicated; not any larger region. If the region-without-sensors in this new world-with-sensors is indeed a duplicate of the original region-without-sensors, then it would seem that any effects on the being’s brain (and hence his conscious life — I’m assuming physicalism here, obviously) that are due to the sensors must be confined to regions in the world outside of the region-without-sensors. So while it would be accurate to say that that world contains a being with a sense of asymmetry, it’s not at all clear that we would say that the region-without-sensors contains a being with a sense of asymmetry. Does a region containing me, minus the region of space occupied by my left kidney, contain a person two kidneys, or a person with one kidney? If you pick the latter answer, then I don’t see why one should say that the region-without-sensors contains a being with an upset sense of symmetry. After all, all the “upset” is outside that region. And what if I ask if the region taken up by my right kidney contains a person with two kidneys? Does any region, even a point, that is a proper part of the region taken up by my entire body contain a person with two kidneys?

One might try to get around this by arguing that you can’t have two conscious beings in the same world such that one is a part of the other. Then you could say that there is only one conscious life that we can assign to any given region and its proper parts, and somehow argue towards discounting the conscious life that is unaffected by the sensors in favour of the conscious life that is affected by the sensors. However, even if we accept the principle of having only one conscious life assigned to a being and its proper parts, I see no reason to always decide in favour of the conscious life that incorporates “more sensors”.

Geometry Movie

This is just brilliant (HT: Douglas Kutach). Funny how the comments at Google Video mostly display perplexity as to the point of the exercise.

Perplexed

Am I the only one who doesn’t understand why, if one is not a big fan of David Lewis, one should not be a big fan of Wittgenstein? The two are about as different in philosophical style and substance as it gets, no?

I find Wittgenstein’s methodology much more grounded than Lewis’s.

Warning: Naive Meta-metaphysical Comments Ahead

I have a lot of sympathy with James Ladyman’s perplexity with certain approaches to metaphysics. (Craig Callender’s comment best summarises my view on the matter.) I, too, could not understand how the question he mocks is interesting. But never mind that — the thing that I find most disturbing about large parts of contemporary analytic metaphysics is how so much of it depends on “intuitive” principles like Locke’s principle that Callender mentions. I read The Plurality of Worlds just last year, and perhaps I was/am too philosophically naive to appreciate it, but for large parts of the book I kept thinking, “OK, this argument would be interesting if I actually agreed with any of the principles it begins with, but since so many of these principles are poorly justified, I don’t really care about this argument any more than I care about the average crossword puzzle.” Those who buy into more of Lewisian metaphysics doubtless disagree with me about the strength of the justification of said principles. But so much metaphysics seems to be spun out, in ever longer threads of argument, on the basis of those principles, and to someone who doesn’t accept those principles, those swathes of metaphysics look pointless.

For complicated reasons, my writing sample addressed a question that interests largely contemporary metaphysicians, and I started out being interested in it because someone had put forward a seemingly good case for a counterintuitive conclusion — interested in it as a mere puzzle. But as I worked on it I became convinced that the question itself was not important. It was important if you bought into a certain strand of Lewisian metaphysics; if you rejected the basic principles of that strand of metaphysics, it would be hard to see what implications an answer to that question would have. By the time I was seriously sick of the topic, it was rather too late to produce a different writing sample, so I stuck with it, but the final weeks polishing it were painful, to say the least. In any case, it’s served its purpose, and I did learn a lot from the process. It also pretty much forced my introduction to Lewisian metaphysics, and I don’t suppose I could have escaped such an introduction indefinitely.

Antipodean clocks

Jeanne Peijnenburg has a video of Huw Price making a lame joke about the direction of time.

First try with PhilPapers

I just tried to import the philosophy of physics papers from my CiteULike library into PhilPapers. There doesn’t seem to be a way to import citations from a BibTeX file; we can import them only in plain text format. So I used CiteULike’s citation export function to get a text bibliography of the papers, did some painstaking editing to make sure there was only one paper per line, and input the list into the box provided under “Batch Import” for each category in PhilPapers. It recognised only about a quarter of the papers on there. Next, I tried importing all the papers tagged “time” in my library, and none were recognised. (Yes, I will put this feedback on the PhilPapers forum have submitted my feedback on this issue.) So at this point of time I’d still stick with CiteULike, especially when it also has social tagging functions that PhilPapers doesn’t. I’ve found many an interesting paper tag-surfing on CiteULike. I can also see who has libraries similar to mine, see what is in their libraries, and choose to “watch” their libraries for any new items they add.

I have to say I’m not as excited about PhilPapers as many others seem to be, because I already keep up with new papers via journal RSS feeds and Online Papers in Philosophy, and I was already very satisfied with CiteULike’s provisions for keeping track of papers I read. Also, it’s nice to have all the papers I read, whether in philosophy or the natural sciences or social sciences or computer vision, in the same place, and I can do that on CiteULike but not on PhilPapers.

Junkyard

[More clearing out of old drafts. This is junk from just before graduation.]

Like every idealistic freshman physics major, I owned the entire set of Feynman Lectures. In my first year I actually had time to read through a significant proportion of the first volume. That was unthinkable from my second year on, when I got involved in research, got distracted by philosophy and music and as a result took above-normal loads of courses, and so on. Nevertheless, I still had some sort of affection for them, perhaps as symbols of my self-proclaimed interest in physics and of the care with which I treated my books.

Today I sold the entire set for $40. Mainly because I already have too many books to ship back home, and I remembered getting the set for not much more than that back home. But I won’t be rushing out to buy them once I get back.

All this being a long-winded way to explain the feeling of wasted effort that has beset me when I’ve had the chance to ponder my physics education. The physics compartment of my brain now feels like a junkyard: a ragbag of three years of tools acquired in undergraduate physics, but no substance to practise them on. It feels inexplicably as though I ought to clear the junk before I can begin building up my understanding. But, as with real life junk, I’ll probably procrastinate on clearing the junk, and never get down to actually starting something new.

(Addendum: I was right. If anything, I’ve acquired more junk.)

Keep Right

(I haven’t actually gone on long bike rides or read Wittgenstein in a good while, but I’m trying to clear my backlog of drafts in WordPress, and found this old draft.)

Fatigued and hungry from a long bike ride, and having read a good bit of late Wittgenstein in the last 24 hours, I opened a normal book and was momentarily confused when, resuming reading on the right leaf after flipping a page, I found that the text was not continuous with that on the previous right leaf. A few seconds later, my sugar-deprived brain realised: Oh! The left side is in English too.