Not All Explanations Predict Satisfactorily, and Not All Good Predictions Explain

This short comment on Epstein's (2008) paper and on the response by Thompson and Derr argues that the symmetry between explanation and prediction cannot satisfactorily be discussed without making clear what prediction means - depending on which connotations the authors have with 'prediction' their arguments can or cannot be accepted.[No keywords]

Against inertia

Revised version added 12 March 2012In this paper I challenge the Inertial Theory of language change put forward by Longobardi (2001), which claims that syntactic change does not arise unless caused and that any such change must originate as an ‘interface phenomenon’. It is shown that these two claims and the resulting contention that ‘syntax, by itself, is diachronically completely inert’ (Longobardi 2001: 278), if construed as a substantive, falsifiable theory of diachrony, make predictions that are too strong, and that they cannot be reduced (as seems desirable) to properties of language acquisition. I also express doubt as to the utility and necessity of a methodological/heuristic principle of Inertia, broadly following Lass’s (1980) view of causality.This work was supported by AHRC doctoral award AH/H026924/1

Effects of the tensor force on the ground and first 2+2^{+} states of the magic 54^{54}Ca nucleus

The magic nature of the $^{54}$Ca nucleus is investigated in the light of the recent experimental results. We employ both HFB and HF+BCS methods using Skyrme-type SLy5, SLy5+T and T44 interactions. The evolution of the single-particle spectra is studied for the N=34 isotones: $^{60}$Fe, $^{58}$Cr, $^{56}$Ti and $^{54}$Ca. An increase is obtained in the neutron spin-orbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes $^{54}$Ca a magic nucleus candidate. QRPA calculations on top of HF+BCS are performed to investigate the first $J^{\pi}$=$2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the mean-field part of the calculations. The first $2^{+}$ states indicate a subshell closure for both $^{52}$Ca and $^{54}$Ca nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in $^{52}$Ca and $^{54}$Ca nuclei.Comment: 8 pages, 3 figure

A New Determination Of The Diffuse Galactic and Extragalactic Gamma-Ray Emission

The GALPROP model for cosmic-ray propagation is able to make explicit predictions for the distribution of galactic diffuse gamma-rays. We compare different propagation models with gamma-ray spectra measured by EGRET for various regions of the sky. This allows sensitive tests of alternative explanations for the apparent excess emission observed at GeV gamma-rays. We find that a population of hard-spectrum gamma-ray sources cannot be solely responsible for the excess since it also appears at high latitudes; on the other hand a hard cosmic-ray electron spectrum cannot explain the gamma-ray excess in the inner Galaxy. By normalizing the cosmic ray spectra within reasonable bounds under preservation of their shape we are able to obtain our best prediction of the Galactic component of diffuse gamma rays, and show that away from the Galactic plane it gives an accurate prediction of the observed gamma-ray intensities. On this basis we reevaluate the extragalactic gamma-ray background. We find that for some energies previous work underestimated the Galactic contribution and hence overestimated the background. The new EGRB spectrum shows a positive curvature similar to that expected for models of the extragalactic gamma-ray emission based on contributions from unresolved blazars.Comment: 6 pages, 3 figures, 1 tabl

On the role of explanatory and systematic power in scientific reasoning

The paper investigates measures of explanatory power and how to define the inference schema “Inference to the Best Explanation”. It argues that these measures can also be used to quantify the systematic power of a hypothesis and the inference schema “Inference to the Best Systematization” is defined. It demonstrates that systematic power is a fruitful criterion for theory choice and IBS is truth-conducive. It also shows that even radical Bayesians must admit that systemic power is an integral component of Bayesian reasoning. Finally, the paper puts the achieved results in perspective with van Fraassen’s famous criticism of IB

Competition as rational action : why young children cannot appreciate competitive games

Understanding rational actions requires perspective taking both with respect to means and with respect to objectives. This study addresses the question of whether the two kinds of perspective taking develop simultaneously or in sequence. It is argued that evidence from competitive behavior is best suited for settling this issue. A total of 71 kindergarten children between 3 and 5 years of age participated in a competitive game of dice and were tested on two traditional false belief stories as well as on several control tasks (verbal intelligence, inhibitory control, and working memory). The frequency of competitive poaching moves in the game correlated with correct predictions of mistaken actions in the false belief task. Hierarchical linear regression after controlling for age and control variables showed that false belief understanding significantly predicted the amount of poaching moves. The results speak for an interrelated development of the capacity for “instrumental” and “telic” perspective taking. They are discussed in the light of teleology as opposed to theory use and simulation

Night Thoughts of a Quantum Physicist

The most dramatic developments in theoretical physics in the next millennium are likely to come when we make progress on so far unresolved foundational questions. In this essay I consider two of the deepest problems confronting us, the measurement problem in quantum theory and the problem of relating consciousness to the rest of physics. I survey some recent promising ideas on possible solutions to the measurement problem and explain what a proper physical understanding of consciousness would involve and why it would need new physics.Comment: Article for "Science Into The Next Millennium", a millennial issue of Philosophical Transactions of the Royal Society of Londo

Structural Change and Patterns of International Trade

This paper focuses on economists' understanding of the basic determinants of trade patterns and, in particular, on the manner in which these underlying factors change over time and are affected by various policies. A brief survey contrasts the determinants of the structure of trade emphasized by the Ricardian, Heckscher-Ohlin, and imperfect competition models and discusses how well the predictions of these various theories are supported by empirical evidence. The main conclusion of the survey is that trade economists have been reasonably successful in explaining the structure of trade at any point in time but much less successful in understanding how the determinants of the patterns of trade change over time. This inability to explain how the basic determinants of the structure of trade change over time can lead both to poor predictions and bad policy advice. Given the increased interest in long-term shifts in trading structures, it is argued that trade economists should enlarge their analytical framework by endogenizing to a greater extent the basic economic factors determining these shifts. They must also recognize the endogenous nature of trade policies in their models, if they are to carry out their predictive and evaluative roles in the best possible manner.

Economics, Biology, and Culture: Hodgson on History

This book addresses what the author claims, with considerable justification, to be the foremost challenge confronting the social and behavioral sciences today: the problem of historical specificity. Hodgson poses the question by asking whether we need different theories to understand social and economic behavior in different societies at different stages of their development. He answers the question in the affirmative, and criticizes the economics profession for suggesting that there is one universal model or theory equally suited to all economies and societies at all times. He faults the profession further for no longer worrying much or conducting serious debate about this issue, a development he attributes to the eclipse and eventual demise of institutionalism and historical economics in England, Germany, and the United States