Beaten to It

I have only just realised that Hartle and Srednicki’s recent paper could be considered a refutation of the doomsday argument, which seems to rely on an assumption that we are typical. My first thought upon that realisation was that some philosopher has probably already said at least a large part of what Hartle and Srednicki said. I was right. Here’s one example:

In order for a statistical model to tell us about the parameter of a real population, the model must fit the inferential facts of the matter about that real population. The tank model arguably does not fit the facts of the real problem. In particular, if we reject the fairy story above and accept some variety of materialism, the notion that anyone is uniformly randomly selected from among the total population of the species is beyond far fetched. The bodies that we are, or supervene upon, have a nearly fixed position in the evolutionary order; for example, given what we know of evolution it is silly to suppose that someone’s DNA could precede that of her or his ancestors. Even considering a population without genetic structure, say that of suns, it is outlandish to suppose that a sun containing heavy elements could have been, but was not, formed before the supernovas which gave rise to those elements. There is no possibility that birth can be considered a uniformly random selection process: the probability that any of us should be born significantly far away in the past, or future, is simply zero, given evolutionary theory and elementary facts about our biology, regardless of the ultimate size of homo sapiens.

The Evolution of Fauna in Madagascar

Thanks to an early exposure to Gerald Durrell’s writings and Douglas Adams’ Last Chance to See, I’ve always been fascinated by the wildlife of Madagascar. So this recent paper by Dewar and Richard, “Evolution in the hypervariable environment of Madagascar”, caught my eye. Their central thesis is that many of the peculiarities of fauna on Madagascar is due to the unusually high intraannual variability of rainfall in Madagascar. The interannual variability of the rainfall of these stations, on the other hand, was not significantly different from that of continental African stations that had similar mean annual rainfalls.

The authors argue that this environmental variability accounts for both the unusually extreme iteroparity and unusually extreme semelparity of certain Malagasy mammal groups. The carnivorous mammals are extremely iteroparous, as are some species of lemurs. At the other extreme, the tenrecs are extremely semelparous, as (again) are some species of lemurs. Comparing these mammal groups with their relatives in the same taxa, the authors conclude that such extremes of semelparity and/or iteroparity are unusual for their respective taxa. The adoption of either of these two extreme strategies can be interpreted as a response to extreme environmental variability. Iteroparity is seen as the ultimate risk-spreading strategy, optimal when adult mortality is low but infant mortality is high — having too many offspring in one go could easily backfire in such conditions, since the whole batch could perish due to externally imposed travails, so parents should spread their bets over as many years as possible. Semelparity is seen as the optimal strategy when adult mortality is high but infant mortality is low, for in such conditions the parents should attempt to have as many offspring as quickly possible before perishing in their probably short lives. For the lemurs and tenrecs, there is evidence supporting the relative rates of adult and infant mortality that are supposed to correlate with iteroparity or semelparity. No such evidence, however, was mentioned for the carnivores.

And that’s about it by way of evidence for the hypothesis that the reproductive strategies of Malagasy mammals are due to the high intraannual variability of rainfall in Madagascar. I must say that while I find it plausible, I’m not entirely convinced. One of my concerns is that I don’t see why intraannual variability in rainfall would have so much more impact (at least with regards to reproductive strategies) than interannual variability in rainfall. Presumably there are places in continental Africa with considerably more interannual variability in rainfall than Madagascar has. Prima facie, it doesn’t seem like intraannual variability should be any more damaging or risk-inducing than interannual variability. So why would extremes of reproductive strategies appear particularly commonly in Madagascar and not in those parts of Africa with higher interannual variability of rainfall? A possible answer is that since these other parts are continental, their inhabitants can combat unpredictability by migration, an option not open to Malagasy mammals. Malagasy mammals have to adapt to unpredictability on their home turf, as it were. But is it the combination of isolation and unpredictability that is the explanation, or just the isolation? It would be interesting to study other islands of similar size and isolation to see if Madagascar’s fauna is any more unusual than that of those islands. If the trend of unusual fauna holds across several such locales, then perhaps it is a simple ‘island’ effect rather than a climate effect. Of course, deciding which islands (if any) are comparable in size and isolation to Madagascar is not a straightforward affair. Another interesting thing to do would be to study the life cycles of Malagasy birds. The current evidence, for mammals only, has a narrow enough base to make me nervous about confirmation bias.

Psychopathic Reasoning

A couple of months ago, I finally got round to reading Antonio Damasio’s Descartes’ Error and was quite disappointed by it. I am not convinced of his central thesis that emotions are necessary for reason. He backs this up mainly by pointing to various cases of brain damage to regions that normally deal with ‘emotions’, in which the victims subsequently claim not to be able to experience certain feelings, can reason as well as normal humans on usual intelligence tests, yet have profound difficulties making decisions to get through daily life. Victims that would repeatedly do things that would cause them to lose their jobs, get sent to prison, and so on, even though on paper tests they seemed to be able to reason perfectly well. Strong evidence for the necessity of emotion for reason, no?

My problem with that is that if these victims really have a deficiency of emotion either in general or with respect to certain situations, then why should it be irrational of them to engage in behaviour with consequences that they have no emotional response to? Psychopaths, Damasio says, are irrational: “to everybody’s obvious disadvantage including their own, sociopaths often repeat crimes.” But it’s not obvious that psychopaths disadvantage themselves by repeating crimes. A normal person with intact emotional responses would probably be disadvantaged by being repeatedly jailed and so on. But a sociopath who feels nothing might not find a crime-free life more enjoyable than a life in prison. He is disadvantaged only insofar as what are advantages to normal humans are advantages to psychopaths. I don’t know what Damasio hopes to gain by implicitly assuming ‘advantage’ to be independent of emotional fulfillment. His account does not seem to eliminate the intuitive idea that emotions tell us what goals are desirable and reason tells us how to attain those goals. The case study named Elliot, for example, does impeccably on paper tests on the prediction of and reaction to social situations, but admits that he still wouldn’t know what to do in a real life situation. This would seem to be the expected outcome if he were able to reason from the information given towards the pre-stated goals in the tests, but could not in real life set himself such goals because he was emotionally impaired and could not evaluate the relative desirability of various goals. Framed that way, Damasio’s theory seems a lot less revolutionary than he makes it out to be. I cannot recall a single case study he uses that could not be re-framed the way I re-framed Elliot’s situation.

Was listening to a live recording of a piano duet, following the lower part in the score as I listened, in which one of the players makes an audible mistake. The section in which the mistake occurred is repeated later. As we neared that part in the piece (and perhaps my visually following the score contributed to my delusion, since it meant I was more aware that it was a repeat), I anticipated hearing the mistake again, as though the repeat was performed by recording the previous section and playing the recording.

Herzog on Herzog: Final Excerpts

Before the book goes back to the library. On the emphasis of ‘story structure’ in Hollywood films:

I am just a storyteller who knows if a good story is working or is not, and who writes so fast he cannot afford to think about the structure of the writing. There is such an urgency of telling the tale that inevitably it creates its own structure. Hollywood films might have some ‘structure’ to them, but they have scripts that press the right buttons at the right time, which is essentially filmmaking by numbers. There is a great production and distribution system in Hollywood, something we in Europe should be envious of… But you hardly ever find a really good story any more, a deficit that is known to most of the people who work out there. I see the role of the film director as being akin to that of a storyteller at the market in Marrakech who has a crowd standing around him.

Binning Candy

I’ve always had a tendency to consume a bag of mixed candy according to how many of each colour/shape there are left. I’ll consume what (from a cursory glance) appears to be the most common colour/shape there is first, in order to preserve variety. It never occurred to me to do this by sorting the candy into bins. I don’t think that’s so much because I’m not obsessive as because I’m too lazy to find a clean surface on which to lay out the candy in bins. (I suppose the inside of the candy packaging could be a clean surface, but if you don’t intend to consume the whole packet in one go, that still leaves the problem of finding a new container to store the candy in. Whereas if you tear only a small hole in the packaging you can just use the packaging to store the remaining candy.)

I have no regrets about my research experience in experimental particle physics, and in fact am quite grateful for it, but I certainly do not want to go back to sorting information into bins any time soon. I’m quite OK with the idea of consuming candy according to the commonality of type, but the thought that this involves some sort of implicit binning of the candy makes me a little uneasy.

Why ~x is Meaningless

Over at Methods of Projection, N. N. is unable to make sense of the following passage from Wittgenstein’s notes:

The reason why ~x is meaningless, is simply that we have given no meaning to the symbol ~x. I.e. whereas φx and φp look as if they were of the same type, they are not so because in order to give a meaning to ~x you would have to have some property ~ξ. What symbolizes in φξ is that φ stands to the left of a proper name and obviously this is not so in ~p. What is common to all propositions in which the name of a property (to speak loosely) occurs is that this name stands to the left of a name-form. (Notebooks, 116)

The second sentence in particular stumps him: what does he mean by “whereas φx and φp look as if they were of the same type, they are not so because in order to give a meaning to ~x you would have to have some property ~ξ”? The earlier passage that N. N. quotes gives a clue:

Take φa and φA: and ask what is meant by saying, “There is a thing in φa, and a complex in φA”?
(1) means: (∃x). φx.x = a
(2) (∃x,ψξ). φA = ψx.φx.

First, let me explain why “in order to give a meaning to ~x you would have to have some property ~ξ”. From Wittgenstein’s earlier passage, we see that if we take ~ as a function, then “~a”, where a is an object* and not a property, means “(∃x). ~x.x = a”. So in order to understand what ~a means, we need to know what ~x means, and ~x is a property. The same goes in general for any function : in order to understand what means, we need to know what the property means.

This implies that is different from (taking x to be an object and p to be a property). For we explained above how, if x is a specific object and not just a general placeholder for any argument, the meaning of depends on a property φ(anything). Whereas, according to (2) in the second quoted passage, isn’t dependent on the meaning of a property φ(anything).

*I can’t remember my Wittgenstein terminology, so “object” might be the wrong term to use. By “object” I mean, vaguely, “thing”.

Update: I just realised that some of the confusion is generated by inconsistent terminology. For in the first quoted passage, x is a given object. In the second passage, x is a variable employed to define the given object a.

Forward Deleting in MacBook Terminal

Ok, finally the lack of a forward delete key in the MacBook’s Terminal is seriously annoying me. I followed the instructions here but am told that the command “\e{3~” cannot be found. I downloaded DoubleCommand but found that its settings don’t apply to Terminal. Yes Fn+Delete works as a forward delete key in most applications. Just not in Terminal, which is where I need it most.

More Herzog on Herzog

On “the inadequate imagery of today’s civilization”:

I have the impression that the images that surround us today are worn out; they are abused and useless and exhausted. They are limping and dragging themselves behind the rest of our cultural evolution. When I look at the postcards in tourist shops and the images and the advertisements that surrounds us in magazines, or I turn on the television, or if I walk into a travel agency and see those huge posters with that same tedious image of the Grand Canyon on them, I truly feel there is something dangerous emerging here. The biggest danger, in my opinion, is television because to a certain degree it ruins our vision and makes us very sad and lonesome. Our grandchildren will blame us for not having tossed hand-grenades into TV stations because of commercials. Television kills our imagination and what we end up with are worn-out images because of the inability of too many people to seek out fresh ones.

[...] Look at the depiction of Jesus in our iconography, unchanged since the vanilla ice-cream kitcsh of the Nazarene school of painting in the late nineteenth century. These imgaes alone are sufficient proof that Christianity is moribund.

I suspect he exaggerates the impact of images because he himself is highly sensitive to images, much more so than normal people (as one might expect). Later on in Herzog on Herzog he explains that he can never attend live concerts because he will be so mesmerised by the movement of the bassist’s hands that he will not listen to the music. I’ll have to think more about the notion of “worn-out images”, but prima facie I don’t see how it means anything over and above having been watched by too many people. But how many is too many? Why can an image be watched by too many people? Why is it somehow bad for images to be watched by a large number of people? Why would having too few new images be bad for our imagination? Didn’t Herzog himself, as a child growing up in the ruins of WWII, claim to have had great fun playing games of imaginary scenarios in all the empty houses and such? Are the images in modern, diverse cities simply superifically different, and do not offer as much rein to the imagination as those empty houses?

Frontends for LaTeX on Linux?

I have been quite spoilt by TeXShop on Mac OS X. I have used Emacs + TeX on Linux before but find it extremely user-unfriendly compared to TeXShop. It appears that TeXLive is one of the more popular LaTeX alternatives for Linux, but for some undefinable reason I’ve not been terribly excited by what I’ve read about TeXLive. And I’m tired of Googling for reviews of TexLive or other Linux LaTeX frontends, so this is a last wave for help before I give up and do all my typesetting on my MacBook rather than on my work PC. (I’m lazy about lugging my MacBook to and from work, but since I miserably failed to install VMD on Xubuntu Dapper Drake, and I can’t abide Windows, and they provide only PCs here, I might as well get used to retreating to Mac OS X for the right mix of security, programming tools, and usability.)

Update 18/10/09: I now use AucTeX with Emacs, and am pretty satisfied.