Wednesday, May 26, 2010

Constructive criticism

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


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In this enquiry, the phenomena include historical documents and physical evidence.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.


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?

Monday, May 17, 2010

In defence of objective Bayesianism

Here’s a plug for my new book!

In defence of objective Bayesianism

How strongly should you believe the various propositions that you can express?

That is the key question facing Bayesian epistemology. Subjective Bayesians hold that it is largely (though not entirely) up to the agent as to which degrees of belief to adopt. Objective Bayesians, on the other hand, maintain that appropriate degrees of belief are largely (though not entirely) determined by the agent’s evidence. This book states and defends a version of objective Bayesian epistemology. According to this version, objective Bayesianism is characterized by three norms:
· Probability – degrees of belief should be probabilities
· Calibration – they should be calibrated with evidence
· Equivocation – they should otherwise equivocate between basic outcomes

Objective Bayesianism has been challenged on a number of different fronts. For example, some claim it is poorly motivated, or fails to handle qualitative evidence, or yields counter-intuitive degrees of belief after updating, or suffers from a failure to learn from experience. It has also been accused of being computationally intractable, susceptible to paradox, language dependent, and of not being objective enough.

Especially suitable for graduates or researchers in philosophy of science, foundations of statistics and artificial intelligence, the book argues that these criticisms can be met and that objective Bayesianism is a promising theory with an exciting agenda for further research.

Available now through all good bookshops, or direct from Oxford University
Press at:

Saturday, May 8, 2010

CFP: "Methodology of alleged scientific failure: The crisis of 2008-09" Symposium at EAEPE Conference, Bordeaux (28-30 Oct, 2010)

The latest economic crisis has raised a lot of questions about the state of economics as a scientific endeavor. After the crisis, practicing economics such as Paul Krugman (among many others) started questioning the performance of economics as a science and the explanatory and predictive roles of its highly abstract mathematical models. The following is an indicative passage from Paul Krugman’s NY Times article: “[...] the economics profession went astray because economists, as a group, mistook beauty, clad in impressive-looking mathematics, for truth. [...] When it comes to the all-too-human problem of recessions and depressions, economists need to abandon the neat but wrong solution of assuming that everyone is rational and markets work perfectly. The vision that emerges as the profession rethinks its foundations may not be all that clear; it certainly won’t be neat; but we can hope that it will have the virtue of being at least partly right.”

In July 2009, philosophy of economics was on the cover of The Economist that asked: “What went wrong with economics?” However, although philosophers of economics have been discussing these same issues for a long time, they were not mentioned in The Economist. So it was philosophy of economics that was on the cover of The Economist, not philosophers of economics or any of their contributions. Moreover, philosophers of economics did not actively contribute to the lively methodological discussion after the crisis. So philosophers of economics were late in responding to the pressing questions that economists and the general public were asking.
To improve the situation slightly, we are organizing a symposium at the EAEPE conference in Bordeaux (28-30 October 2010). We are looking for papers that will diagnose the alleged failures of economics, will evaluate the status of economics after the crisis, and will provide some answers to the questions that practicing economists and the general public have been asking about economics.
Please send a proposal for a contribution (400-500 words) to Uskali Mäki and Emrah Aydinonat . Please send your proposals as soon as possible – no later than 30 May 2010.