Sunday, February 21, 2010

Species and Couches

A smart philosopher of biology I know claims to be researching "whether there are (really) species, as opposed to just individuals". So far as I can tell, he is investigating whether biological explanations that appeal to species are not really always better put in terms of individuals. That is, he's studying whether talking about species serves a certain kind of (ineliminable?) role in biological explanation.

That definitely seems worth worth investigating - especially since there are so many cases where the distinction between different species looks very unprincipled. (Because of ring species and ligers it won't do to just say that two things are the same species if they can produce fertile offspring.)

But it seems strange to me that he puts this in terms of `investigating whether species really exist'. This is because, presumably, he thinks couches really exist, and yuppies too, even though we could surely phrase an adequate biological and scientific theory in such a way as not to entail any sentences of the form Ex couch (x) or Ex yuppie(x).

What I THINK might be going on is that he thinks objects need to earn their keep, in a way that concepts don't. That is: it's fine to apply scientifically useless predicates like " a yuppie", but not to introduce scientifically useless *objects* like species. On this reading he would be fine with saying that dogs exist, or that two newts are consepecifics, but not with saying that there are (abstract) objects called species.

But I don't see quite how one would motivate this differential treatment. (Admittedly this may have something to do with my current adherence to the merely logical notion of objecthood). Also, the problems for the notion of species looking unprincipled seem to apply just as much to claims about being a dog or being two animals being conspecific.

*Obviously some scientifically useless objects are bad to introduce, like the flying spagetti monster but that's because their existence would entail false claims about the distribution of matter in space-time. In contrast, just proposing new ways to think of the same old distribution of matter etc. in space-time as constiuting objects e.g. (tables, vs. half tables, vs. complete livingroom sets vs. dearths of tables) in different ways, seems harmless.

[edit: there is something SLIPPERY about the way I am using the concept/object distinction here. must think more about this, and ask the philosopher of bio]

Explanation Puzzle

On the one hand, we think that the fact that a theory T1 allows for "better explanation" of a certain phenomena than T2, gives us reason to believe T1 rather than T2 is correct. It's obvious (if not particularly explanatory) reason to prefer one theory to another that it "does a better job of explaining the data"!

On the other hand, we think that a better explanation can be one that better helps human beings "grock" patterns in the behavior of physical systems which may be mathematically very complex. Given human psychology, attention span etc. a simple ceterus paribus statement about struck matches tending to light can be a better explanation than an explanation that appeals to more specific details. To choose a more extreme example, even if there were a completely successful theory of microphysics, most people feel we would still have an explanatory task. We would still want elegant theories that told us about general high-level patterns in how the microphysical facts would evolve forward through time. (e.g. the ideal gas law, biology and maybe psychology and economics).

But now here's the problem: do we really think that the fact that a theory T allows for nice tractable/human-grockable explanations of high level phenomena makes it more likely to be true? For example:

I find "consider a spherical cow" style economics explanation, or "consider philosophers building up society from a state of nature" style early modern philosophy explanations way more attractive, satisfying, and easy to remember than explanations that cite lots of boring contingent historical facts. But this doesn't really make me feel that these explanations are more plausible, or getting at the heart of matters more.

I mean, I wouldn't be surprised if primate intelligence is optimized for avoiding getting double crossed by other monkeys, and making practical plans etc. so we like explanations better if they relate the explananda to these things (i.e, people with plans). Indeed don't we actually find this with explaining a phenomenon to people in different disciplines- that people familar with different areas find different explanations more satisfying?

We like explanations where lots of correct consequences "fall out immediately" from a tiny theory. But what seems to fall out immediately (vs. just be an ugly mathematical consequence) may well depend on how familiar you are with inferences of that kind. And folk (belief/desire) psychology is something we are *all* very familiar with from daily life. Hence, when someone says "this electron wants to escape the other electron" or "countries covet land", we have lots of immediate ideas about what behavior should follow from that, because we are experts at drawing consequences from belief desire psychology, and then we just convert these consequences back to the task at hand.

But surely allowing for nice parallels to common problems in monkey social climbing, is not a feature that has much to do with genuine theoretical elegance/ how likely a theory is to be correct.

On Rationalizing Explanations

Philosophy papers (like David Lewis' Languages and Language) often seem to want to explain the fact that some X is actually the case (e.g. we all use the word "fire" in roughly the same ways) by showing why it would be rational for people to make X the case/preserve that state of affairs X. But this seems potentially problematic:

a) Historians wouldn't generally accept the idea that showing why declaring war was rational for a certain leader explains why he actually did declare war. If the presedent has the policy of always taking the first proposal suggested when he's tired and wants to go home, and P was the first proposal suggested, the fact that it would be rational to do P rather than Q is not the correct explanation for why the president actually did P rather than Q. Similarly if the president never even considered Q, the fact that P serves his interests better than Q seems like an incorrect explanation for his choosing Q.

b) More generally, rationality explanations seem to have exactly the issues that philosophers of biology make a huge deal about when considering evolutionary fitness explanations: the mere fact that some trait would be eliminated by natural selection isn't always the correct explanation for why we don't find it. For example, the fact that humans don't levitate isn't explained by natural selection, but rather by the fact that the total space of mutations available from the original organisms doesn't include that. (That is: plausibly, even if all creatures had had all the offspring they could, and lived as long as they could so there was no culling to generate natural selection, we would *still* find 0 creatures that levitate. )

Applied to the David Lewis case of conventions, this works out in the following way. It *might* be that we get linguistic conventions because once some people are using language a given way, each person works out that it would be rational for them to do the same (this is the nub of lewis' account). Or it might be that most possibilities for doing things differently don't even occur to them - people just brutely follow custom and habit and imitate those around them. (Apparently apes' tool use is like this: chimps in a given area all crack nuts using the same techniques, even though different techniques would work just as well and are used in different areas. Note here that there's no rational benefit to cracking nuts differently from your neighbor). Or it might be some combination of habit plus considerations of rationality. And surely its an empirical matter to find out which.

Given this, I think we can read Lewis either as making a bold empirical conjecture, or as explaining actual behavior by comparing it to the behavior of a simpler, but in some respects similar, model system (as often happens in biology).

bold empirical conjecture: In fact, adherence to linguistic conventions is always produced, not by custom and habit whereby doesn't occur to people to behave otherwise, but by speakers recognizing that it would be rational for them to continue with the convention.

simplified model system explanation: In ideal system S (where there are no limitations on computational power etc and people always behave in the way that best advances their aims), linguistic conventions arise and persist. The actual world of people talking is `relevantly similar enough' to S, for these facts about S to explain how actual linguistic conventions arise and persist in the actual world. [Slot in whatever notion of relevantly similar explains how facts about waves in infinitely deep oceans can explain facts about waves in actual finitely deep oceans].

Saturday, February 13, 2010

this keeps coming up...

You might think that a satisfactory account for mathematical knowledge would have to at least prevent us from ever winding up with/keeping contradictory mathematical beliefs.

But this is wrong for two reasons:
a) OLD REASON: "We" did have contradictory beliefs about mathematics at various periods in history (naive set theory, inconsistent reasoning about infinity).
b) NEW REASON: Many people have contradictory beliefs about baldness (as brought out by the sorites paradox), but this doesn't prevent them from knowing many things about baldness, who is bald etc.

de re beliefs about numbers?

I just read some Azzuni which seemed to attribute the following argument to Burge:

"The difference between de re and de dicto thought, is that de dicto thought can have content that `goes beyond' your concepts and picks up info from the environment. So if I think de dicto "the nearest vase is green" the proposition which this expresses is purely determined by my concepts. Whereas, if I think de re "*that* vase is green", this picks up content from the context (in particular it claims something which would be false if that vase got painted white, but some other vase wound up getting put in front of me instead).

Now, (one might go on to think) , this suggests mathematical thought involves a de re component. Why? A de re component would explain how mathematical talk can pick up content from facts about matheamatical objects outside the head. Hence, it could explain why the truth conditions for mathematical facts go beyond my (probably recursively axiomatizable) inference dispositions."

The problem with this is that, as Burge himself is famous for pointing out, what someone means by concept-words like arthritis can also require one to `go to the context', (in a slightly broader sense) of how experts near the speaker use the word arthritis, to determine what proposition/truth conditions a sentence about ``arthritis'' has.

So, if the evidence is just that mathematical truths can depend on stuff that `goes beyond'*[Yuck, if there were some typographic convention stronger than academic shudder quotes I'd be using it here :)] our presumably recursively axiomatizable inference dispositions, then I see no evidence for the claim that our number talk is de re. Dependence on broader context could be achieved either by the the object-word "3" functioning as some kind of hidden de re ostension, or the concept word "is 3rd in a number-sequence" (or whatever other pseudo-definite description you would want to associate with three) having a meaning that isn't entirely determined by stuff in the head.

Many other things seem shady too, but I should really read more of Burge's own words before getting too dismissive :).
[edit: ok Burge himself does not seem to be making this argument in the relevant article which is here]