Ontological commitment and mathematics : inaugural lecture delivered at Rhodes University

Inaugural lecture delivered at Rhodes UniversityRhodes University Libraries (Digitisation

Oor die Begrip wese

In die wetenskap moet noodwendig van abstraksies gebruik gemaak word by die sistematisering en korrelering van kennis

Navorsing aan ons universiteite

Die taak van ’n universiteit is tweeledig, navorsing en dosering, of verwerwing en oordrag van kennis

Die formalisme in die wiskunde

Die kernprobleeni in die Wysbegeerte van die Wiskunde is die vraag na die aard van mateniatiese entiteite en hulle verhoudings. As die Wiskunde sy aanspraak om erkenning as deel van die wetenskap wil handhaaf, moet dit bestaan uit oordele aangaande ’n deel van die werk- likheid. Die wetenskap soek immers kontak met die werklikheid waaroor dit geldige oordele wil formuleer. Die Wiskunde maak dus aanspraak op waarheid, d.w.s. die oordele van die Wiskunde moet ooreenstem met die gegewens wat daardie bepaalde deel van die werklikheid bied. Voordat bepaal kan word wat hierdie waarheid, waarop die Wiskunde aanspraak maak, eintlik is, moet ons weet waaroor die oordele van die Wiskunde gaan, m.a.w. die vraag 11a die aard, en in besonder die syns- wyse van die wiskundige entiteite en die verhoudings wat daartussen hestaan, moet beantwoord word

Geestigheid en A.G. Visser

Dit is ’n bekende verskynsel in die literatuur dat verskillende tye verskillende menings oor ’n digter se werk kan he. Hiervoor bestaan daar baie redes. Dit beteken dat ’n digter se werk ’n boeiendheid besit wat eers later, miskien lank na die digter se dood, duideliker word. By Visser het daar ’n herwaardering ingetree ten opsigte van onder meer sy geestigheid. Hiervoor is daar ’n verskeidenheid redes, wat ek hieronder sal aansny. Dit gaan terug na een oorkoepelende rede wat teweeggebring het dat Visser se geestigheid in die soeklig staan. En dit het te doen met die veranderde werklikheidsbelewing in die modeme tyd, wat die plek en waarde van geestigheid raak. Hierop sal ek ingaan. Tot op hede is daar twee duidelik onderskeibare benaderings van Visser se geestigheid

Invloed van wiskundige denke

In this article the author indicates how mathematical thought has exerted influence in various fields. The questions around the nature of mathematical knowledge and how this might be obtained had their foundation in philosophy. According to Plato man comes lo the truth by means of pure thought, independent of sensory perception. Bergson feels that truth if obtained through “intuition" and not by means of the intellect. Russel reduced mathematical truths to logical truths. According to him logical truths are true exclusively on the basis of the meanings adduced to words and sentences. The extreme criteria laid down by the logical positivists for the meaningfulness of a statement have led to the situation of statements such as “God exists" having no sense any more. Mathematical thought has exerted influence also via philosophy and the mathematical sciences on man’s sense of values and views on the meaning of human existence. The descript ion of man purely in terms of concepts, which was so successful in physics leads to superficiality in the concept of the meaning of human existence, and has alienated man from those things in which he had to find inspiration and tranquillity. The way to oppose nihilism lies in the fact that all aspects of reality and of being human have to he places in a balanced relationship and the correct perspective, and that all these have to be evaluated in the right light

Evaluation of waist-to-height ratio to predict 5 year cardiometabolic risk in sub-Saharan African adults

Simple, low-cost central obesity measures may help identify individuals with increased cardiometabolic disease risk, although it is unclear which measures perform best in African adults. We aimed to: 1) cross-sectionally compare the accuracy of existing waist-to-height ratio (WHtR) and waist circumference (WC) thresholds to identify individuals with hypertension, pre-diabetes, or dyslipidaemia; 2) identify optimal WC and WHtR thresholds to detect CVD risk in this African population; and 3) assess which measure best predicts 5-year CVD riskPeer reviewedFinal Accepted Versio

Monastic retreat and pastoral care in the Dutch Reformed tradition

Of late, there has been a growing interest in retreat among clergy and members of congregations in the Dutch Reformed tradition in South Africa. The article investigates the relevance of the monastic traditions for this growing interest in Reformed circles. It focuses on aspects of retreat such as the role of holy places in the monastic traditions (e.g., monasteries, cathedrals, retreat centers) and the experience of silence, solitude, regeneration, divine presence and spiritual formation. Proceeding from an epistemological reflection on the subject as described in a previous article, the aim of this article is to explore the “action of retreat” as a narrative research journey and pilgrimage in order to investigate the relevance of the Benedictine, Franciscan and Taizé monastic-mystic traditions (seen as an associative/mystic spirituality) for retreat in the Dutch Reformed tradition (which is seen as a disassociative/rational/ dogmatic spirituality)

SALT Spectropolarimetry and Self-Consistent SED and Polarization Modeling of Blazars

We report on recent results from a target-of-opportunity program to obtain spectropolarimetry observations with the Southern African Large Telescope (SALT) on flaring gamma-ray blazars. SALT spectropolarimetry and contemporaneous multi-wavelength spectral energy distribution (SED) data are being modelled self-consistently with a leptonic single-zone model. Such modeling provides an accurate estimate of the degree of order of the magnetic field in the emission region and the thermal contributions (from the host galaxy and the accretion disk) to the SED, thus putting strong constraints on the physical parameters of the gamma-ray emitting region. For the specific case of the $\gamma$-ray blazar 4C+01.02, we demonstrate that the combined SED and spectropolarimetry modeling constrains the mass of the central black hole in this blazar to $M_{\rm BH} \sim 10^9 \, M_{\odot}$.Comment: Submitted to Galaxies - Proceedings of "Polarized Emission from Astrophysical Jets", Ierapetra, Crete, June 12 - 16, 201

2-(Ammonio­meth­yl)pyridinium sulfate monohydrate

In the crystal of the title hydrated molecular salt, C6H10N2 2+·SO4 2−·H2O, N—H⋯O and O—H⋯O hydrogen bonds link the mol­ecules into layers parallel to the ab plane. C—H⋯O hydrogen bonds are observed both within these layers and between mol­ecules and ions in adjacent layers