There is a great deal of justified concern about continuity through scientific theory change. Our thesis is that, particularly in physics, such continuity can be appropriately captured at the level of conceptual frameworks using conceptual space models. Indeed, we contend that the conceptual spaces of three of our most important physical theories—Classical Mechanics, Special Relativity Theory, and Quantum Mechanics —have already been so modelled as phase-spaces. Working with their phase-space formulations, one can trace the conceptual changes and continuities in transitioning (...) from CM to QM, and from CM to SRT. By offering a revised severity-ordering of changes that conceptual frameworks can undergo, we provide reasons to doubt the commonly held view that CM is conceptually closer to SRT than QM. (shrink)

Objective Bayesians hold that degrees of belief ought to be chosen in the set of probability functions calibrated with one’s evidence. The particular choice of degrees of belief is via some objective, i.e., not agent-dependent, inference process that, in general, selects the most equivocal probabilities from among those compatible with one’s evidence. Maximising entropy is what drives these inference processes in recent works by Williamson and Masterton though they disagree as to what should have its entropy maximised. With regard to (...) the probability function one should adopt as one’s belief function, Williamson advocates selecting the probability function with greatest entropy compatible with one’s evidence while Masterton advocates selecting the expected probability function relative to the density function with greatest entropy compatible with one’s evidence. In this paper we discuss the significant relative strengths of these two positions. In particular, Masterton’s original proposal is further developed and investigated to reveal its significant properties; including its equivalence to the centre of mass inference process and its ability to accommodate higher order evidence. (shrink)

In a legendary technical report, the Google founders sketched a wisdom-of-crowds justification for PageRank arguing that the algorithm, by aggregating incoming links to webpages in a sophisticated way, tracks importance on the web. On this reading of the report, webpages that have a high impact as measured by PageRank are supposed to be important webpages in a sense of importance that is not reducible to mere impact or popularity. In this paper, we look at the state of the art regarding (...) the more precise statement of the thesis that PageRank and other similar in-link-based ranking algorithms can be justified by reference to the wisdom of crowds. We argue that neither the influential preferential attachment models due to Barabási and Albert in nor the recent model introduced by Masterton et al. in allows for a satisfactory wisdom-of-crowds justification of PageRank. As a remedy, we suggest that future work should explore “dual models” of linking on the web, i.e., models that combine the two previous approaches. Dual models view links as being attracted to both popularity and importance. (shrink)

Social epistemology studies knowledge and justified belief acquisition through organized group cooperation. To do this, the way such group cooperation is structured has to be modeled. The obvious way of modeling a group structure is with a directed graph; unfortunately, most types of social cooperation directed at epistemological aims are variably implementable, including in their structural expression. Furthermore, the frequency with which a practice is implemented in a certain way can vary with topology. This entails that the topology of social (...) practices directed toward epistemological ends has to be modeled by a set of directed graphs, or their equivalent, together with a probability distribution over that set. In theory, this is eminently possible; however, there are considerable practical obstacles to the specification of a practice’s topology in this way. This paper examines these practical difficulties and concludes that todays sampling protocols are either far too slow to handle pratices with 10 or more participants, or else prone to produce misleading evaluations. (shrink)

We address the fundamental question why we should use PageRank and similar link-based algorithms in search engines, if at all. In a legendary article from 1998, the Google founders gave an intriguing wisdom-of-crowds justification for PageRank according to which the latter tracks quality online. This striking suggestion stands in contrast to the view that PageRank merely tracks what is popular. However, Masterton and Olsson showed that web-ecologies generated by Google-like assumptions essentially fail to reflect the scale-free structure of the web. (...) They pointed to attraction to popularity or a rich-get-richer effect being the likely main cause of scalefreeness. In this article, we explore dual models of linking behavior, i.e. models that combine attraction to importance with attraction to popularity. Our results, obtained through computer simulation, indicate that there exist dual models that give rise both to a wisdom-of-crowds effect for PageRank and to scale-free web-graphs, thus giving a partial vindication of the wisdom-of-crowds thesis for the real web. Future work should explore larger web-graphs as well as other aspects pertaining to the empirical plausibility of dual linking models. (shrink)

The very last of words of Naming and Necessity are ‘The third lecture suggests that a good deal of what contemporary philosophy regards as mere physical necessity is actually necessary tout court. The question how far this can be pushed is one I leave for further work.’ Kripke (1980). To my knowledge he never conducted that further work; moreover, no one following him has wished to take up the baton either. Herein, I argue that in general, physical necessity is neither (...) reducible to, nor implies, tout court necessity. Furthermore, it is demonstrated that even if Kripke’s speculations are restricted to a subset of the physical necessities where it might be granted that all such are necessary tout court, physical necessity is still not reducible to tout court necessity. (shrink)

According to Williamson , the difference between empirical subjective Bayesians and objective Bayesians is that, while both hold reasonable credence to be calibrated to evidence, the objectivist also takes such credence to be as equivocal as such calibration allows. However, Williamson’s prescription for equivocation generates constraints on reasonable credence that are objectionable. Herein Williamson’s calibration norm is explicated in a novel way that permits an alternative equivocation norm. On this alternative account, evidence calibrated probability functions are recognised as implications of (...) evidence calibrated density functions defined over chance hypotheses. The objective Bayesian equivocates between these calibrated density functions rather than between the calibrated probability functions themselves. The result is an objective Bayesianism that avoids the main problem afflicting Williamson’s original proposal. (shrink)

The very last of words of Naming and Necessity are ‘The third lecture suggests that a good deal of what contemporary philosophy regards as mere physical necessity is actually necessary tout court. The question how far this can be pushed is one I leave for further work.’ Kripke (1980). To my knowledge he never conducted that further work; moreover, no one following him has wished to take up the baton either. Herein, I argue that in general, physical necessity is neither (...) reducible to, nor implies, tout court necessity. Furthermore, it is demonstrated that even if Kripke’s speculations are restricted to a subset of the physical necessities where it might be granted that all such are necessary tout court, physical necessity is still not reducible to tout court necessity. (shrink)

Book review of Jon Williamson's `In Defence of objective Bayesianism'.

In 1977 van Fraassen showed convincingly, and in detail, how one can give a dissentive answer to the question `[a]re there necessities in nature?'. In this paper I follow his lead and show in a similar fashion and detail, how it is possible to give a dissentive answer to: Are there probabilities in nature? This is achieved by giving a partial analysis—with the aid of Kaplanian pragmatics—of objective chance in terms of that credence that is reasonable where prevailing laws and (...) conditions exhaust one's evidence. This template belongs firmly within the established Bayesian program of analysing objective chance as ultimate belief. Its contribution to that program is the same as van Fraassen's contribution to the empiricist program of analysing physical necessity; namely, it demonstrates the logical possibility of such an analysis. (shrink)

Lewis' concept of admissibility was introduced as an integral part of his famous Principal Principle; the principle that initial rational/reasonable belief should conform to objective chance unless there is evidence to the contrary. At that time Lewis offered only the rough and ready characterisation that evidence not to the contrary of such dependence is admissible. This, together with some sufficiency conditions, served well enough until it became clear that admissibility was central to debates on the viability of Humean Supervenience and (...) the analysis of objective chance. In response, Thau and Lewis refined the concept of admissibility in various ways. Since the mid 90's those who have employed the concept have, with minor variations and additions, followed the Thau/Lewis line. Yet, in the 30 years since its introduction what has been all too conspicuous by its absence is a full formal definition of admissibility and its degrees. Herein a family of definitions—all in terms of screening off by chance—that capture much that has been agreed about admissibility are proposed and evaluated; one of which is ultimately found to be serviceable as a definition schema for relative admissibility and its degrees. (shrink)

info:eu-repo/semantics/publishedVersion.

In the literature one finds two non-equivalent responses to forecasts; deference and updating. Herein it is demonstrated that, under certain conditions, both responses are entirely determined by one’s beliefs as regards the calibration of the forecaster. Further it is argued that the choice as to whether to defer to, or update on, a forecast is determined by the aim of the recipient of that forecast. If the aim of the recipient is to match their credence with the prevailing objective chances, (...) they should defer to the forecast; if it is to maximize the veritistic value of their beliefs, they should update on the forecast. (shrink)