Friday, February 23, 2007

Leuven Epistemology

The Epistemology Workshop has just ended (one talk early, as unfortunately Crispin Wright was not able to attend). Highlights included Finn Spicer laying into the Canberra Planning of Frank Jackson as applied to the project of analysing our concept of knowledge. Finn offered some challenges to the idea that the best theory of the relationship between our platitudinous intuitions about knowledge and the reference of our concept of knowledge is Jackson's.

This made me think more about the Canberra Plan, and in particular how it offers an answer to Field's question (from his recent paper on the a priori):

"Why should the fact, if it is one, that certain beliefs ... are integral to the meaning of a concept show that these principles are correct? ... Maybe the meaning we've attached to these terms is a bad one that is irremediably bound up with error."

The Canberra Planner's answer, I take it, is that the platitudes determine what if anything our concept refers to, but good old-fashioned empirical work has to be done to find out whether there is anything that is a good enough deserver to allow us to decide that the concept does refer. In other words, good old-fashioned empirical work is needed before we have a right to treat the concept as if it is not 'a bad one that is irremediably bound up with error' but rather one whose attendent platitudes get things right to a reasonable degree.

(Of course, this answer does not seem to rescue conceptual analysis as a means of securing a priori knowledge. Therefore it is not as good as a concept grounding account. But that goes without saying on this blog. :)

I leave you with another image from Leuven. Here I am with my new mate Cardinal Mercier (founder of the Higher Institute of Philosophy):

Wednesday, February 21, 2007

KU Leuven Reference Library

This impressive-looking library has a chequered history which I can't resist reporting. In WWI the library was burned down (c. 300,000 books lost, plus manuscripts collected from 1425 onwards), and it was rebuilt with financial help from American universities. Then it burned down again in WWII (c. 900,000 books and manuscripts lost), and was rebuilt again afterwards.* Then in the 1960s, language (and other) issues resulted in the university at Leuven becoming Flemish-speaking and a new Francophone university being built at Louvain-la-Neuve. The reference library collection was split in half.

The tower houses a lovely-sounding 63-bell carillon which I was lucky enough to hear playing when this photo was taken.

I'm less convinced about the dead insect on a stick. Apparently it symbolizes 'the relationship between art and science'. I think I don't get it.

* "So I built a third one. That burned down, fell over, then sank into the swamp. But the fourth one stayed up."

Tuesday, February 20, 2007


I'm currently visiting Leuven for a few days, where I'll be giving a paper at an epistemology workshop at the Katholieke Universiteit Leuven's Philosophy Institute on Thursday. The programme should be fun: the other speakers are Marietje van der Schaar, Duncan Pritchard, Igor Douven, Finn Spicer, Rene Van Woudenberg and Crispin Wright, and every paper will have a commentator. More news here soon I expect ...

Wednesday, February 14, 2007

Curve-Fitting and Description-Dependence

I started thinking about this after Aidan Lyon's excellent talk on the curve-fitting problem yesterday.

Graham Priest in his 1976 article Gruesome Simplicity (this link is to JSTOR) discusses curve-fitting as a way of making inductive inferences. When we plot observed values of two related quantities x and y on a graph, we have several options for which curve to draw between them. The simplicity of the curve has to be traded off against fit with the existing data points, and it is a taxing problem to say how best this should be done. Yet we often do think we can choose an appropriate curve, and use it to make predictions concerning as-yet-unobserved values of x and y.

What Priest shows is that 'certain very natural transformations' on data sets result in different curves appearing to be 'best' and correspondingly conflicting predictions being delivered. Priest therefore claims to have shown that 'which prediction is best depends not on the situation but how you describe it. (Equivalent descriptions do not give the same answers.)' (p. 432). This sort of description-dependence sounds unsettling; we would like our predictions to be sensitive only to our data, and not affected by accidental features of the ways we happen to represent that data.

It seems to have been accepted in the subsequent literature that Priest's problem, if it cannot be avoided, establishes a worrying kind of description-dependence. But in my opinion the existence of such description-dependence is not established by Priest's argument. To get that conclusion, we would need an additional premise: that when we perform the transformations on the data that generate the new predictions, we are just redescribing the same situation, as opposed to considering a different situation.

What counts as a different situation? Well, for these purposes, we should consider any difference which is not merely a difference in our descriptions a difference in the situation described. (If this were not what Priest had in mind, i.e. if there were room for something else to differ besides the situation and our descriptions of it, it would not follow that a difference in prediction without a difference in the situation described must be due merely to a difference merely in our descriptions.)

There is reason to suppose that many 'transformations' of data – even very simple a priori ones – lead to description of a different situation. A priori inference, for example, enables me to conclude from This plane figure has three angles that This plane figure has three sides, but these are two different propositions involving different properties. The difference between these two propositions is (plausibly) not merely redescription; what's being described – which language-independent properties are being talked about – differs in each case.

Similarly, turning to one of Priest's own examples, when we transform data about velocity and momentum into data about velocity and kinetic energy, there is a difference in what is described and not merely a difference in description. Momentum and kinetic energy are related by the equation E = pv/2, but they are not therefore the same thing.

This might help make Priest's result a little less unsettling than Priest himself suggests. It is less philosophically disturbing to conclude that thinking about two different situations can lead us to make two different predictions than to conclude that describing the same situation two different ways can lead us to make two different predictions.

That's not to say it makes the result entirely comfortable; the difference in predictions is still somewhat disturbing, given that we know the transformation relationship between the two situations. It may well be interesting and difficult, to say what (if anything) we ought to predict in these circumstances. But it has not yet been established that the problem arises due to description-dependence.

Monday, February 12, 2007

Williamson On The Epistemology Of Modality

Chapter 5 of Tim Williamson's new book The Philosophy of Philosophy argues that modal knowledge is a species of counterfactual knowledge. Why should we believe this? The only reason offered is that there is a logical equivalence between modal claims and certain counterfactuals. In Williamson's words (p. 25):

"Given that the equivalences … are logically true, metaphysically modal thinking is logically equivalent to a special case of counterfactual thinking, and the epistemology of the former is tantamount to a special case of the epistemology of the latter."

But it does not follow from the bare fact that modal claims are logically equivalent to certain counterfactual claims that modal epistemology is tantamount to a special case of counterfactual epistemology. By analogy, it does not follow from the fact that that disjunctive propositions AvB are equivalent to negated conjunctive propositions ~(~A&~B) that the epistemology of disjunctive propositions is a special case of the epistemology of negated propositions. Nor does it follow from the fact that atomic propositions A are logically equivalent to conjunctive propositions A&A that the epistemology of atomic propositions is a special case of the epistemology of conjunctive propositions.

The equivalences cited by Williamson cannot by themselves establish that knowing certain counterfactuals is the way – or even our usual way – of knowing modal facts. At most, they might be taken to suggest that knowing the relevant counterfactuals is a way of knowing modal facts. I take it that epistemologists of modality are (rightly) more centrally interested in the question of how we do know about modality than in the question of how we might know about modality.

Moreover, without supplementation, flagging the mere existence of logical equivalences is not even to specify a way of coming to know about modality. We are left wondering what the supposed way of knowing is supposed to be like. Is it envisaged that we know the modal claims by first knowing the counterfactual claims and then deriving the modal claims which are equivalent to them? If so, it looks very unlikely that many of us are using this route to modal knowledge much of the time. Most people could not work through the relevant derivations if they tried, and even those who could certainly don't seem to be doing that kind of thing very often. On the other hand, if the envisaged route to modal knowledge does not go via derivation from the equivalent counterfactuals, what is it like? And what is the epistemological significance of the equivalence?

Thursday, February 01, 2007

Photos Of Philosophers

There are some great photos among this new set by Steve Pyke, who also created the classic collection Philosophers. I love Hartry Field's little text, which totally avoids the sort of pretentiousness which must be a temptation when you're asked to write something like this:

"A nice thing about philosophy of the sort I do is that it can never be used to justify wars or oppress the disadvantaged or anything like that.
This follows from a more general principle."


(Hat tip: Jason Stanley. Personally I think Stanley's own self-portrait about half way down this page rivals Pyke's photo of him for capturing the soul of the subject.)