A difference between science and the humanities?

This post is going to be overly ambitious and overreaching, but isn't that what the blogosphere is all about? Classes started this past week, and I am teaching an upper-level course in philosophy of science. I started the class with the (overly ambitious) question 'What is science?' We had an interesting conversation, and I learned a bit from my students. There was an extended discussion about which particular parts of forensic science really do count as science, and the question 'What is science?' really matters there, because once something is declared accepted science, then it can be admitted into evidence in a court of law.

I had one thought concerning how to distinguish science from the humanities, which I didn't share with my students, but I figured I might try to articulate here. I think it may just be a slightly different way of putting a tired old point, but here goes.

Both the sciences and the humanities seek understanding; both offer explanations of various bits of the world. At a very abstract level, though, the kind of things each tries to explain is different. Obviously, (e.g.) Hamlet is a very different kind of thing than (e.g.) thermometer readings -- I have a more 'formal' difference in mind. When an English professor gives an interpretation of Hamlet, she has (basically: see (3) in next paragraph) ALL the stuff to be explained in front of her: the text is complete, finished. To put the point in terms of evidence instead of explanation, all the data/evidence she can offer for her preferred interpretation of the text is already in. This stands in clear contrast with (most of?) the sciences: new data is constantly being gathered, and new observations need to be explained. If a similar process were occurring in the Hamlet case, a new Act of that play would be produced every week, and various interpretations were shown to be stronger or weaker as new 'data' (i.e. texts) came streaming in.

I think many parts of philosophy are more like the Hamlet case. Take ethics for example. Murder, stealing, lying, etc. are morally wrong. This is in some sense the 'received/ established text' from which the ethicist works: an ethical theory has to explain why those things are wrong. Of course, there are thought-experiments designed to probe various parts of our ethical intuitions, but (1) these often yield contentious/ equivocal results, and (2) more importantly, I only want to say philosophy is more like the Hamlet case, not that it's identical. (Plus, (3) the English professor could potentially get some new information "around the margins" (to put it metaphorically): further historical details of Shakespeare's life, earlier drafts of texts, various facts about the circumstances of production, etc. -- there is clearly a continuum here with absolutely no new data on one end and lots of new data on the other.)

Another philosophical example would be philosophy of arithmetic. We've known that 7+5=12 for some time now, and the philosopher wants to explain how and why we know it's true. We're not getting a whole lot of new 'data' about arithmetic. As a final example, consider the enterprise that falls under the heading of 'interpretation' of various special scientific theories -- an enterprise which is frequently thought of as being particularly close to science. This industry is perhaps most developed in the case of quantum mechanics, but it thrives in general relativity, statistical mechanics, population genetics, etc. as well. On my criterion, these projects (usually) fall much closer to the 'humanities' end of the spectrum: the game here is to take some standard formulation of the theory in question (e.g. of quantum mechanics) and provide an explanation of that theory. The formulation of (e.g.) quantum mechanics is, I think, like the text of Hamlet, insofar as it is taken to exhaust what needs to be explained. However, sometimes this explanation will (either by itself, or with further specification) generate new experimental predictions. When that happens (as in some cases of spontaneous-collapse interpretations of quantum mechanics), then the project becomes more scientific on the above criterion, and less like the humanities.

Perhaps the criterion I've suggested here can partly explain why many (though by no means all!) physicists express exasperation with the philosophy of physics, and consider the enterprise pointless.

realism and the limits of scientific explanation

Long time, no blog. I finally got back a few days ago from the last of my visits to schools for final job interviews. It was very interesting and instructive to observe non-Pittsburgh philosophers in their native habitats. I should know by the end of this week where I'll be next year.

In lieu of an actual post, I am putting up the handout I used at a couple of my job talks. As a result, it looks programmatic/ bullet-pointy; but I tried condensing this into a normal post, and it was just far too long. If you can make out what's going on, I would really appreciate any feedback/ comments/ eviscerations from readers.

REALISM AND THE LIMITS OF SCIENTIFIC EXPLANATION

The argument

(P1) Scientists do not accept explanations that explain only one (type of) already accepted fact.
(P2) Scientific realism, as it appears in the no-miracles argument, explains only one type of already accepted fact (namely, the empirical adequacy or instrumental success of mature scientific theories).
(P3) Naturalistic philosophers of science “should employ no methods other than those used by the scientists themselves” (Psillos 1999, 78).

Therefore, naturalistic philosophers of science should not accept scientific realism as it appears in the no-miracles argument.

Explanation and defense of (P1)

Explanations that explain only one type of already accepted fact
(i) generate no new predictive content, even when conjoined with all relevant available background information [‘already accepted fact’], and
(ii) do not unify facts previously considered unrelated [‘only one type’].

Evidence for (P1): Scientists reject
- Virtus dormativa-style explanations
- ‘Vital forces’/ entelechies as explanations of developmental regularities
- Kepler’s explanation of the number of planets, and the ratios of distances between them, via the five perfect geometrical solids
- ‘Just-so stories’ in evolutionary biology

The no-miracles argument for scientific realism

Abductive inference schema
(1) p
(2) q is the best explanation of p
Therefore, q

No-miracles argument for scientific realism
(1) Mature scientific theories are predictively successful.
(2) The (approximate) truth of mature scientific theories best explains their predictive success.
Therefore, Mature scientific theories are (approximately) true.

Proponents of the no-miracles argument (Putnam, Boyd, Psillos) accept (P3), appealing to naturalism to justify their abductive inference to scientific realism. Putnam claims that scientific realism is “the only scientific explanation of the success of science” (1975, 73).

The argument for (P2): Scientific realism (i.e., the claim that mature scientific theories are approximately true)
(i) generates no new predictions,
(ii) unifies no apparently disparate facts, and
(iii) explains only one previously accepted fact, viz., science’s predictive success.

First real post: abduction from limited evidence

I am currently teaching a summer session class called "How Science Works." The aim of the class (according to the course description) is to "introduce science and scientific ways of thinking to students who have not had much contact with science." One of the big-picture themes I am trying to develop in the course is that, in many cases, scientific reasoning is just extra-careful common-sense reasoning made precise. Thus, for some of their homework assignments, I ask students for an example from their lives where they (or someone they know) have used whatever scientific strategy we are studying that day.

On their last homework assignment, I asked them to give an everyday example of an abductive inference that is supported by independent sources of evidence, a very common kind of inference in good scientific practice. There were some very clever answers; the most common one was the cheating significant other: I never see the significant other with someone else, but I do observe her staying out late, hanging up the phone immediately when I stop by unexpectedly, and various other secretive behaviors.

But, unsurprisingly, some students did not quite understand the requirement for evidence from multiple independent sources, and gave an example of an abduction from just one. (These examples often involved some sort of roommate malfeasance: "My favorite CD is no longer in its case, so my roommate must have taken it without asking.")

But this mistake raised one version of a question I've been wondering about off and on for a while now. This version of the question is:

What is the epistemological status of abductive inferences (also known as 'inferences to the best explanation') that have only one (independent) source of evidence?

To make this a slightly more well-posed question (or at least a question more amenable to philosophers of science), we can pose the question more naturalistically: how does science regard and treat such inferences?

My gut-feeling answer is that such inferences are regarded as 'merely hypothetical' or otherwise second-class citizens -- like atomic theory in the 19th C, for example (for an account of this historical episode very congenial to my point, see Penelope Maddy's "A Problem in the Foundations of Set Theory, Journal of Philosophy Nov. 1990, pp. 623-625). Often such abductions from limited evidence are pronounced ad hoc. And, in biology, this also seems to be the reason many people call certain adaptionist accounts of certain biological traits "just-so-stories": if the only evidence we have for that adaptationist account is the way the animal looks or acts now, then we just don't have strong reason to accept that account. If we found enough sources of independent evidence for our conjecture, even the strong anti-adaptationists might come around.

I think this question (of the status of abductive inferences based on only one evidential source) is an interesting one in its own right. But it seems it also has implications for philosophy proper: many philosophical positions purport to explain only one thing, and lack the kind of consilience that good abductive inferences in the sciences enjoy. To take just one example, scientific realism aims to explain the success of science -- and as far as I can tell, that's it. (At least some other realisms will definitely fall in the same boat.) Certain critics of scientific realism (van Fraassen, for one) criticize all instances of "inference to the best explanation" (IBE), and use that criticism as an argument against scientific realism (which is supposedly the result of an instance of IBE). However, we may not need to throw out all instances of IBE in order to have a good argument against the realist -- we need only act like the scientists (as I portrayed them in the previous paragraph): accept only those instances of IBE for which we have more than one independent source of evidence.