Hacking and Franklin on the Functional Complexity of Evidence

After posting my paper here, in the last few days, I've just happened to come across two fabulous statements related to my position. Of course, just when you start to think you're doing something a little bit original, you come across all kinds of people saying basically the same thing.

Ian Hacking, on the first page of the monumental "Experimentation and Scientific Realism":

Experiments, the philosophers say, are of value only when they test theory. . . So we lack even a terminology to describe the many varied roles of experiment.  (Hacking 1982, p. 71)

And Allan Franklin, on the first page of his Selectivity and Discord:

Experiment plays many roles in science.  One of its important roles is to test theories and provide the basis for scientific knowledge.  It can also call for a new theory. . . Experiment can provide hints about the structure or mathematical form of a theory, and it can provide evidence for the existence of the entities involved in our theory. . . it may also have a life of its own, independent of theory: Scientists may investigate a phenomenon just because it looks interesting. Such experiments may provide evidence for future theories to explain. (Franklin 2002, p. 1)

It is a nice surprise to find myself in such good company.  The aim of my paper, of course, is to try to provide a coherent picture of and some terminology for the various roles of evidence.  One of the points that I make in the paper, which I'm not sure Hacking or Franklin would accept, is that there is a useful (functional) distinction to be drawn between observational and experimental evidence.  I suspect they might even say that I leave some roles out of my picture.

Varieties of Evidence Redux

About a year ago, I posted three blog posts here, arguing that scientific evidence serves a more complex and dynamic set of functions in scientific inquiry than simply supporting hypotheses.  I've finally manage to work the idea out in a form that I'm satisfied with:

The Functional Complexity of Scientific Evidence (Draft)

I'm especially indebted to the commenters on this blog for the content of section 6, including Thomas Basbøll, Greg Frost-Arnold, Gabriele Contessa, and Eric Winsberg.  (I hope I've appropriate credit where credit is due there.  I was a bit stymied in how exactly to refer to a conversation we had on the blog, and so made the acknowledgments there fairly general.  Advice on that point is welcome.)

I hope I've managed to present it in a compelling way and answer the objections in a satisfactory way, even though I'm sure many traditionalist won't be convinced.  The goal in this paper is to motivate the need for more complex, functionalist, dynamic model of evidence in contrast with the oversimplification of the traditional-type model, to set out in detail such a model, to illustrate it with an example, and to reply to some basic objections.  I've got a second paper in progress which applies the basic framework to a variety of problems of evidence, from theory-ladenness and the experiment's regress to "evidence for use" and evidence-based public policy.  My central claim there is that this apparently diverse set of problems all share a set of assumptions, and the strongest way to solve them all is to adopt the dynamic evidential functionalism that I've laid out in this first paper.

One reason that I needed to whip this paper into shape is that I'm presenting on the topic of the sequel at the Pitt workshop on scientific experimentation.  Getting this in final form is part of finishing up that paper.  The working title there is "From the Experimenter’s Regress to Evidence-Based Policy: The Functional Complexity of Scientific Evidence."

If anyone gets a chance to look at the paper, I'd appreciate any comments, here or via email. 

Constructive criticism

I've been thinking about constructive empiricism. (This is a boiled down version of a more rambling post over at my blog.)

AN OBJECTION

Van Fraassen doesn't see the disagreement between realists and constructive empiricists as being about what we ought to believe. Instead, he sees the dispute as being about the proper aim of science. Here's one way he put the point:

Scientific realism and constructive empiricism are. as I understand them, not epistemologies but views of what science is. Both views characterize science as an activity with an aim - a point, a criterion of success - and construe (unqualified) acceptance of science as involving the belief that science meets that criterion. According to scientific realism the aim is truth (literally true theories about what things are like). Constructive empiricism sees the aim as not truth but empirical adequacy. [Analysis 58.3, 1998]

So scientific realism and constructive empiricism (as van Fraassen understands them) both need for there to be a purpose to science altogether - SCIENCE write large. As I intimate in my dcog paper, I don't think there is such a purpose. Even supposing that there is, however, it is not something that can be divined by a priori rumination. As van Fraassen admits, our account of what science is about must accommodate the actual history of science. It is a partly empirical enquiry responsible to evidence.

In this enquiry, the phenomena include historical documents and physical evidence. They probably also include the actual historical activities of scientists. Yet under no account is the aim or purpose of the activity itself among the phenomena. The aim of the activity is a posit, introduced as part of a philosophical-historical theory. Moreover, it is an unobservable posit.

Therefore, an agnostic (who declines to believe in the unobservable posits of even the most successful theories) must decline to believe in the aim of science. This follows regardless of what the aim of science is posited to be, so an agnostic must decline to be a constructive empiricist. This is a problem for van Fraassen, who thinks that agnosticism is a comfortable epistemic position for constructive empiricists. I see two possible replies.

First, he might stick to his agnostic guns. Refusing to believe in constructive empiricism, he still might accept it. That is, he could treat constructive empiricism as involving not a true theory about science but instead an empirically adequate one. This would involve some mental gymnastics, but being an agnostic already involves mental gymnastics. This meta move is only a small additional flourish.

Second, he might deny that the aim of science is a theoretical posit. Perhaps history is not a science. Perhaps discovering what what science is is not history. I don't see this line as terribly promising.

A QUESTION

Van Fraassen has argued that we need a richer epistemology, one which allows for more than just binary beliefs or probabilistic degrees of belief. Moreover, he resists formal models of belief as direct representations of entities in the mind or brain. Yet he does seem to genuinely believe in states of opinion, "real epistemic attitudes, pointed to by traditional epistemology, which cannot be accommodated in the probabilist models we have developed so far" [ibid.].

As Sellars and Churchland convincingly argue, though, epistemic attitudes like this are not among the immediate phenomena of the world. We posit them as part of a (folk) psychological theory. An agnostic about scientific and folk scientific theories ought not to believe in beliefs.

Does van Fraassen acknowledge this anywhere? or is his psychological musing a personal matter rather than an announcement ex cathedra qua constructive empiricist?