Darwinian Dialectics

Review of: Robert J. Richards and Michael Ruse: Debating Darwin. University of Chicago Press, Chicago. 2016. ISBN: 9780226384429, 320 pages, price: $30.00 (hardcover

Drug Laws, Ethics, and History

In this paper, I present and criticize several historical arguments in favour of prohibition and criminalization of illicit psychoactive substances. I consider several versions of Charles Brent’s argument from drug harms and an argument from addiction based on Kantian view on autonomy. My criticism will mainly rely on empirical evidence on drugs, drug use, and addiction. I think that in light of this evidence, all of the arguments lose their cogency or can be refuted altogether. Moreover, the evidence reveals an inconsistency in the international drug law framework. In conclusion, I therefore provide a general argument challenging the legitimacy of the existing distinction between licit and illicit drugs based on the inconsistency

Affording illusions? Natural Information and the Problem of Misperception

There are two related points at which J.J. Gibson’s ecological theory of visual perception remains remarkably underspecified: Firstly, the notion of information for perception is not explicated in much detail beyond the claim that it “specifies” the environment for perception, and, thus being an objective affair, enables an organism to perceive action possibilities or “affordances.” Secondly, misperceptions of affordances and perceptual illusions are not clearly distinguished from each other. Although the first claim seems to suggest that any perceptual illusion amounts to the misperception of affordances, there might be some relevant differences between various ways of getting things wrong. In this essay, Gibson’s notion of “specifying” information shall be reconstructed along the lines of Fred Dretske’s relational theory of information. This refined notion of information for perception will then be used to carve out the distinction between perceptual illusions and the misperception of affordances, with some help from the “Empirical Strategy” (developed by Purves et al.). It will be maintained that there are cases where perceptual illusions actually help an organism to correctly perceive an affordance. In such cases, the prima facie misrendered informational relations involved are kept intact by a set of appropriate transformation rules. Two of Gibson’s intuitions shall thus be preserved: the objectivity of informational relations and the empowerment of the organism as an active perceiver who uses those objective relations to his specific ends

The Morality of Euthanasia

In this paper, I defend the view that the requested euthanasia of adults is morally permissible and should be legalised; I use an argument from analogy which compares physician-assisted euthanasia with morally less ambiguous and, in my opinion, an acceptable instance of mercy killing. I also respond to several objections that either try to prove that the instance of mercy killing is not acceptable, or that there is a fundamental difference between these two cases of killing. Furthermore, in the remainder of the paper I defend the moral permissibility and legalisation of euthanasia against several objections that appeared in local disputes on this issue, based on the concepts of the limits of freedom, the slippery slope, and the needlessness of euthanasia

‘The Action of the Brain’. Machine Models and Adaptive Functions in Turing and Ashby

Given the personal acquaintance between Alan M. Turing and W. Ross Ashby and the partial proximity of their research fields, a comparative view of Turing’s and Ashby’s work on modelling “the action of the brain” (letter from Turing to Ashby, 1946) will help to shed light on the seemingly strict symbolic/embodied dichotomy: While it is clear that Turing was committed to formal, computational and Ashby to material, analogue methods of modelling, there is no straightforward mapping of these approaches onto symbol-based AI and embodiment-centered views respectively. Instead, it will be demonstrated that both approaches, starting from a formal core, were at least partly concerned with biological and embodied phenomena, albeit in revealingly distinct ways

The Formation of the First Galaxies

The primary concern of this thesis is to understand the formation and properties of the first galaxies, as well as the influence of the first stars in terms of radiative, mechanical and chemical feedback. In particular, we elucidate the role of turbulence, ionizing radiation by massive Population III stars, mechanical feedback by highly energetic supernovae, and chemical enrichment. In light of the next generation of ground- and space based telescopes, we derive their observational signature in terms of recombination radiation, bremsstrahlung and 21 cm emission. We find that the cumulative 21 cm signal of the first H II regions will likely be observable by the planned SKA, while the recombination radiation from the first starbursts might be observable by JWST. These probes are essential to test the theoretical framework of the first stars and galaxies and shed some light on this elusive period of cosmic history.Comment: Ph. D. Thesis, University of Heidelberg, 2009, 212 pages, 55 figures, pdf available at http://www.ita.uni-heidelberg.de/~tgreif/thesis.shtml?lang=e

Multifrequency radiation hydrodynamics simulations of H2 line emission in primordial, star-forming clouds

We investigate the collapse of primordial gas in a minihalo with three-dimensional radiation hydrodynamics simulations that accurately model the transfer of H2 line emission. For this purpose, we have implemented a multiline, multifrequency ray-tracing scheme in the moving-mesh code Arepo that is capable of adaptively refining rays based on the Healpix algorithm, as well as a hybrid equilibrium/non-equilibrium primordial chemistry solver. We find that a multifrequency treatment of the individual H2 lines is essential, since for high optical depths the smaller cross-section in the wings of the lines greatly increases the amount of energy that can escape. The influence of Doppler shifts due to bulk velocities is comparatively small, since systematic velocity differences in the cloud are typically smaller than the sound speed. During the initial collapse phase, the radially averaged escape fraction agrees relatively well with the fit of Ripamonti & Abel. However, in general it is not advisable to use a simple density-dependent fitting function, since the escape fraction depends on many factors and does not capture the suppression of density perturbations due to the diffusion of radiation. The Sobolev method overestimates the escape fraction by more than an order of magnitude, since the properties of the gas change on scales smaller than the Sobolev length.Comment: 19 pages, 1 table, 10 figures, published in MNRA

Contract enforcement and institutions among the Maghribi Traders: Refuting Edwards and Ogilvie

Edwards and Ogilvie (2008) dispute the empirical basis for the view (Greif, e.g., 1989, 1994,2006) that multilateral reputation mechanism mitigated agency problems among the eleventh-century Maghribi traders. They assert that the relations among merchants and agents were law-based. This paper refutes this assertion using quantitative and documentary evidence thereby vindicating the position that the legal system had a marginal role in mitigating agency problems in long-distance trade in this historical era. Edwards and Ogilvie constantly present legal actions in non-trade related legal cases as evidence for a reliance on the legal system for matters pertaining to long-distance trade. Their criticism of Greif’s documentary analysis also fails scrutiny. The claim that merchants' relations with their overseas agents were law-based is wrong. This paper is based on quantitative analyses of the corpuses containing the hundreds of documents on which the literature relies and a careful review of the documents and the literature Edwards and Ogilvie cite. Their assertion is shown to be based on unrepresentative and irrelevant examples, an inaccurate description of the literature, and a consistent misreading of the few sources they consulted. In particular, their examples for the use of the court are mainly taken from mandatory legal procedures associated with sorting out the assets and liabilities of deceased traders’ estates. Such examples do not support the claim that agency relations were law-based. The quantitative analysis reveals that empirical basis for the multilateral reputation view is stronger than originally perceived. This paper also sheds light on the roles of the legal system and reputation mechanism during this period.institutions; contract-enforcement; reputation; Maghribi traders; agency relations

Contract Enforcement and Institutions among the Maghribi Traders: Refuting Edwards and Ogilvie

Edwards and Ogilvie dispute the empirical basis of the view that a multilateral reputation mechanism mitigated agency problems among the eleventh-century Maghribi traders. They allege that the relations among merchants and agents were founded in law. This paper refutes this assertion using comprehensive quantitative analyses of all available primary sources and a careful review of the documents and the literature Edwards and Ogilvie cite. Among recent new quantitative findings reported: (1) less than one percent of the documents’ content is devoted to legal activity on any matter. (2) The legal system was mainly used for mandatory, non-trade related matters. (3) The documents reflect thousands of agency relations but there are less than six court documents possibly reflecting its use in agency disputes. (4) A ten percent random sample of all the documents finds no trade-related legal actions among Maghribis beyond those in the court documents. (5) About 75 percent of agency relations were not based on a legal contract. The paper also reaffirms the accuracy of Greif’s documentary examples and sheds light on the roles of the legal system and reputation mechanism during this period.multilateral reputation mechanism, Maghribi traders, Edwards and Ogilvie

Review of emissivity calculations for diatomic gases first quarterly progress report, 29 jun. - 28 sep. 1964

Absorption spectrum calculations for diatomic gases - chemistr