2/13/2006

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.

6 comments:

Anonymous said...

Well, I came to the argument with a firmly entrenched bias. But while I've always thought that scientific realism doesn't actually do anything that we need to have done, I thought this was an unusually elegant way of getting to that conclusion.

Anonymous said...

I am no fan of the no miracles argument,and I'm sure I missing something obvious here, but how about the following defense of it: a poor explanation is better than no explanation at all, and the realist explanation is the only explanation on offer. Putnam, recall, paired his NMA with a negative argument for realism- the failure of non-realist explanations of success.

Greg Frost-Arnold said...

Protagoras -- Thanks for the vote of confidence!

Kenny -- I need to think about what you've said a bit more. I'm actually not completely sure I've understood you; I'll study your comments and let you know if anything occurs to me.

David -- Welcome, and thanks for the comment. It's a good point, and prima facie plausible; but I think the stuff under my heading "Evidence for (P1)" counts as (quasi-)empirical evidence for the claim that there are some explanations that are so bad, that (the vast majority of) scientists would rather leave the fact unexplained. And more generally, scientific explanations do come to an end somewhere, for a particular science at a particular time (e.g. with fundmental laws).

marco said...

Greg -
I enjoyed this - original stuff. Two objections:
(i) there are many examples of scientific posits explaining only one type of fact. E.g. we believe we see the trajectory of a particle because that explains the trail in the cloud chamber.
(ii) One way of running the NMA is theory by theory. So let's grant that scientists only like a theory if it explains a range of types of fact. Theory T explains F1, F2 and F3 -type facts. But explanation is factive: only true theories explain. So T is true.

Greg Frost-Arnold said...

Hi Marco --

Thanks for this. Re: (ii), I think you can now see why I asked, in the post your commented on previously, why I would want [local realism + global anti-realism] to be viable: my argument says that the case-by-case NMA is OK, since (good) individual theories do generate new predictions or unify previously disparate phenomena. But the global NMA doesn't. (I have not given an argument FOR anti-realism, just an argument against ONE justification for global realism. So [Global anti-realism + local realism] is not forced upon me, but I do wonder whether it's consistent.)

Re: (ii): I probably need to think about this a bit more, and you may be right. I hadn't really thought about SINGULAR explanations much; I think it's clear that positing the existence of electrons does generate new predictions and perhaps unifies various phenomena, but I hadn't really thought about positing THIS PARTICULAR electron's existence explaining THIS PARTICULAR track. But, for the NMA issue, I think that doesn't matter, since the NMA isn't supposed to offer a singular explanation.

Anonymous said...

David - "a poor explanation is better than no explanation at all"

Is it? That sounds more like a defence for religion than for a philosophy of science. What's wrong with suspending judgement? It's not as if any progress is being arrested without that explanation.