Wednesday, October 06, 2010

Is Explanation the Foundation? (by guest blogger G. Randolph Mayes)

One of my main interests is explanation. I think there may be no other concept that philosophers lean on so heavily, yet understand so poorly. Here are some examples of how critical the concept of explanation has become to contemporary philosophical debates.

1. A popular defense of scientific realism is that the existence of theoretical entities provides the best explanation of the success of the scientific enterprise.

2. A popular view concerning the nature of inductive rationality is that it rests on an inference to the best explanation.

3. A popular argument for the for the existence of other minds is that other minds provide the best explanation of the behavior of other bodies.

4. A popular argument for the existence of God is that a divine intelligence is the best explanation of the observed order in the universe.

This is a short list. The concept of explanation has been invoked in similar ways to analyze the nature of knowledge, theories, reduction, belief revision, and abstract entities. Interestingly, few of the very smart people who defend these views tell us what explanation is. The reason is simple: we don’t really know. The dirty secret is that explanation is just no better understood than any of the things that explanation is invoked to explain. In fact, it is actually worse than that. If you spend some time studying the many different theories of explanation that have been developed during the last 60 years or so, you’ll find that most of them give little explicit support to these arguments.

The reason for this is worth knowing. Most philosophical theories of explanation have been developed in an attempt to identify the essential features of a good scientific explanation. The good-making features of explanation were generally agreed to be those that would account for how explanation produces (and expresses) scientific understanding. There are many different views about this, but an assumption common to most of them is that a good scientific explanation must be based on true theories and observations. That sounds pretty reasonable, but here’s the rub: If truth is a necessary condition of explanatory goodness, then it makes no sense at all to claim that a theory’s explanatory goodness is our basis for thinking it is true.

All of the arguments noted above do just this, invoking a principle commonly known as “inference to the best explanation” (IBE, aka ‘abduction’). This idea, first articulated by Charles Peirce, has been the hope of philosophy ever since W.V.O. Quine pounded the last nail into the coffin of classical empiricism. This latter tradition had sought in vain to demonstrate that inductive rationality could ultimately be reduced to logic. For many, IBE is a principle that, while not purely logical, might serve as a new ‘naturalized’ foundation of inductive rationality.

Bas van Fraassen, the great neo-positivist, has blown the whistle on IBE most loudly, arguing that it is actually irrational. One of his criticisms is quite simple: It is literally impossible to infer the best explanation; all we can infer is the best explanation we have come up with so far. It may just be the best of a bad lot.

One way to understand the disconnect between traditional theories of explanation and IBE is to note that there are two fundamentally different ways of thinking about explanation. In one, basically transactional sense, explanations are the sorts of things we seek from pre-existing reserves of expert knowledge. When we ask scientists why the night sky is dark or why it feels good to scratch an itch, we typically accept as true whatever empirical claims they make in answering our question. Our sense of the quality of the explanation is limited to how well we think this information has answered the question we’ve posed. This, I think, is the model implicit in most traditional theories of explanation. The aim is to show in what sense, beyond the mere truth of the claims, that science can be said to provide the best answers.

In my view, IBE has more to do with a second sense of explanation, belonging to the context of discovery rather than communication of expert knowledge. In this sense, explaining is a creative process of hypothesis formation in response to novel or otherwise surprising information. It can occur within a single individual, or within a group, but in either case it occurs because of the absence of authoritative answers. It is in this sense of the term that it can make sense to adopt a claim on the basis of its explanatory power.

Interestingly, much of the work done on transactional accounts of explanation is highly relevant to the discovery sense of the term. Many of the salient features of good explanations are the same in both, notably: increased predictive power, simplicity, and consilience. (This point is made especially clearly in the work of philosophically trained cognitive psychologists like Tania Lombrozo.) What is not at all clear, however, is that any of the IBE arguments noted above will have the intended impact when the relevant sense of explanation belongs more to what Reichenbach called “the context of discovery” rather than the “context of justification.”


Matt McCormick said...

This isn't exactly to your point about the different accounts of exp, Randy, but relevant. In many God arguments, particularly about the alleged design of the universe, theists insist that God is a better explanation than atheistic accounts. And it often becomes clear in what they say that part of what is making the explanation "better" in this sense is that the God hypothesis satisfies a number of criteria that are not typically permitted in scientific explanations. The God answer provides personal meaning, it provides moral guidance, and tells us that everything has a purpose rather than the world's being indifferent. None of those are commonly acknowledged as legitimate criteria for what makes one explanation better than another in other contexts, but here, somehow, they are widely accepted as salient. It seems like the Van Fraassen point you invoke suggests an answer: While the God hypothesis may provide some cognitive satisfaction on these vectors, we can't in virtue of that sort of satisfaction lay claim to have found the truth. The IBE may only be the best of a bad lot, and if part of what makes it the IBE is that it provides personal meaning, then so much the worse.


G. Randolph Mayes said...

Matt, interesting point. You're anticipating some of what I'll be talking about on my next post, which concerns the illusion of understanding or to what extent our sense of understanding reliably indicates the quality of the explanation given. It seems likely that our sense of understanding is more strongly asserted in more primitive forms of explanation, like belief-desire explanation, which would partially account for the intuitive appeal of Aristotelian/ teleological explanations of the motions of physical objects. I suppose the contentious aspect of your own point is the claim that science has no use for this way of explaining things, since they are the stock and trade of anthropology, ethology, psychology etc. But you don't need to be a radical reductionist to believe that the intentional stance is unlikely to be the most productive one for explaining the origin of the universe.

Eric Schwitzgebel said...

Randy, I'm wondering if the fan of IBE can use this simple dodge: There are several aspects of a "good" (in the relevant sense) explanation, only one of which is truth. The presence of those *other* aspects is then a sign of the presence of truth as well.

Clark Goble said...

I'm not sure Peirce's abduction should be seen as "best explanation." I know some scientific realists have latched onto Peirce's terminology but it really seems like they use it quite different from how Peirce does. Inference to best explanation is much more wrapped up in Peirce's notion of induction.

Which doesn't necessarily resolve the issue. Although I think Peirce's logic of abduction is one way to avoid the controversy.

G. Randolph Mayes said...

Eric, it might be a start. A shoddy refutation would go something like: "There are several aspects of a good (in the relevant sense) woman, only one of which is brains. The presence of those other aspects is then a sign of the presence of brains as well." But maybe the argument doesn't even work very well for other criteria of explanatory power. We wouldn't, e.g., think that an explanation that is true and unified and simple, would necessarily have a lot of predictive power. (Assume, for example, that God exists and then consider the explanation "God willed it.") What's needed here is an explicit argument that theories with greater explanatory power are more likely to be true than ones that aren't. But, as van Fraassen would remind us, 'more likely' can still be extremely unlikely.

G. Randolph Mayes said...

Clark, You may be right about that. I haven't visited Peirce's writings for quite some time. In the Stanford Encyclopedia entry on Peirce, Robert Burch claims that Peirce sees abduction as hypothesis generation in the early stages of inquiry, rather than a species of induction. That's about what I think.

Clark Goble said...

Peirce basically sees abduction as the uncanny ability to make correct guesses. He never formalizes it and in a few areas says it is inherently non-rule based. Later on he tends to use it as the initial step in scientific development. (It's been a while since I read the SEP but I think that's the sense they latch onto) As I see it Peirce sees abduction as a kind of logic tied into our fallible capacity to make correct guesses. He thinks this developed evolutionarily. One could attempt to formalize this with bayesian inference or neural nets but I think that goes beyond Peirce's use.

Best explanation always seems inductive since it is the conclusion attributed to the general on the basis of a small sampling.

If one were to use abduction though then I think that does offer a strong defense of realism. Not just scientific realism but the scholastic realism Peirce defended. Although to be fair others have seen an inherent tension between Peirce's realism and his pragmatism. But that's a point of contention in Peircean scholarship.

I think the move from Peircean abduction to IBE is more due to a lot of people (including Peirce scholars like Putnam) for Peirce's position. Putnam famously didn't like Peirce's conception of truth and I don't think he likes Peirce's conception of abduction either.

Sean Landis said...

"What's needed here is an explicit argument that theories with greater explanatory power are more likely to be true than ones that aren't."

I'm not familiar with all the literature on explanation, but at least in Inference to the Best Explanation (chapter 9 in particular), Peter Lipton offers an argument of this kind. As he puts it, we can ground a theory's likeliness partly in terms of its loveliness.

G. Randolph Mayes said...

Sean, I think Lipton uses 'loveliness' as more or less synonymous with 'understanding.' He says, for example that the "central claim is that scientists take loveliness as a guide to likeliness, that the explanation that would, if correct, provide the most understanding, is the explanation that is judged likeliest to be correct." And then he goes on to acknowledge that to explicate this claim you need to give a full accounting of the explanatory virtues that are constitutive of understanding. As I read him, at least, he doesn't go on to make an argument that the explanatory virtues actually confer greater likelihood, but that scientists actually do take loveliness as a guide to likeliness. So, ultimately, it is an attempt to justify IBE by claiming that it is an accurate account of scientific practice. Which, btw, I think would be a very useful thing to demonstrate.