Aristotle quoted the "timaeus" more than any other dialogue of plato. these quotations are here analyzed at length for their accuracy and what they reveal about aristotle's agreement or disagreement with his mentor. seven topics are treated: the receptacle, simple bodies, qualities, motion, time, the soul, and scientific method. subsidiary topics include: space, weight, natural law, psycho-somatic relations, and implications for modern science. the conclusion is drawn that aristotle correctly reports plato, and agrees with his general emphases, although he uses (...) fresh, original explanations. (shrink)
Using standard imaging techniques of electron microscopy it is not possible to resolve the partial dislocations having the equilibrium separation for dissociated dislocations in the pure face-centred cubic metals. Consequently the stacking-fault energy ? cannot be determined from direct measurements of the separations of the partials. In this paper it is demonstrated that such determinations are possible using the weak-beam method of electron microscopy. The separations of Shockley partial dislocations in silver and copper have been measured, as a function of (...) dislocation line orientation, using this method. From these measurements, the values ?silver= 16·3+1·7 erg cm?2 and ?copper= 41±9 erg cm?2 have been obtained from analyses based on anisotropic elasticity theory. (shrink)
Jenkins (2007) charges that the language advanced in Beall (2007) is either expressively impoverished, or inconsistent. We argue that Jenkins’ objections are based on unreasonably strong constraints on formal theories of truth. Our primary concern is not to defend the ‘paranormal’ framework advanced in Beall, but to respond to a common – and implausible – ‘revenge’-style charge directed at a certain class of formal theories of truth and paradox.
Knowledge and Faith in Thomas Aquinas. John I. Jenkins. Cambridge, Cambridge University Press, 1997. pp. 267. 35.00 hb. ISBN 0-521-58126-5. The Cambridge Companion to Aquinas. Norman Kretzmann and Eleonore Stump. Cambridge, Cambridge University Press, 1993. pp. 302. 12.95 pb. ISBN 0-521-43769-5. The Metaphysics of Theism: Aquinas's Natural Theology in the Summa Contra Gentiles I. Norman Kretzmann. Oxford, Oxford University Press, 1997. pp. 302. 35.00 hb. ISBN 0-19-823660-3. Thomas Aquinas: God and Explanations. C. F. J. Martin. Edinburgh, Edinburgh University Press, (...) 1997. pp. 212. 40.00 hb. ISBN 0-7486-0901-6. Theories of Cognition in the Later Middle Ages. Robert Pasnau. Cambridge, Cambridge University Press, 1997. pp. 330. 37.00 hb. ISBN 0-521-58368-3. (shrink)
For years theists have claimed that the constants of physics had to be finely tuned by God to the values that have for life in the universe to be possible. In my column of June, 2009 I showed that many of these claims are based on an improper analysis of the data. Even some of the competent scientists who write on this subject commit the fallacy of holding all the parameters constant and varying just one. When you allow all to (...) vary, you find that changes to one parameter can be easily compensated for by changes to another, leaving the ingredients for life in place. This point is also made nicely in a recent Scientific American cover story by Alejandro Jenkins and Gilad Perez. In this column I will discuss perhaps the most cited example of claimed fine-tuning, the Hoyle resonance. In 1953 the famous astronomer Fred Hoyle calculated that the production of carbon would not occur with sufficient probability unless that probability was boosted by the presence of an excited nuclear state of C12 at a very specific energy. In what appeared to be a remarkable victory for anthropic reasoning, Hoyle proposed that this previously unknown state must exist at about 7.7 MeV. (shrink)
The central role played by Darwin's analogy between selection under domestication and that under nature has been adequately appreciated, but I have indicated how important the domesticated organisms also were to other elements of Darwin's theory of evolution-his recognition of “the constant principle of change,” for instance, of the imperfection of adaptation, and of the extent of variation in nature. The further development of his theory and its presentation to the public likewise hinged on frequent reference to domesticates.We have seen (...) that Darwin's reliance on the analogy between domesticated varieties and wild species was a bold and original step, in light of contemporary views on the nature of domesticates. However, as Darwin undoubtedly foresaw, his reliance on the analogy created difficulties as well as solving problems, and these began with his Malthusian codiscoverer of the principle of natural selection, Alfred Russel Wallace. Wallace's paper “On the Tendency of Varieties to Depart Indefinitely from the Original Type,” presented to the Linnean Scoiety along with the first public unveiling of Darwin's theory, states: We see, then, that no inferences as to varieties in a state of nature can be deduced from the observation of those occurring among domestic animals. The two are so much opposed to each other in every circumstance of their existence, that what applies to the one is almost sure not to apply to the other. Domestic animals are abnormal, irregular, artificial; they are subject to varieties which never occur and never can occur in a state of nature.62Much has been made of the similarity of views of Darwin and Wallace, but this quotation surely reveals how utterly different their views were on what to Darwin was an important matter. Several critics of the Origin saw Darwin's reliance on the domesticates as his Achilles heel. As Young has pointed out, Samuel Wilberforce included the following passage in his attack on the Origin: Nor must we pass over unnoticed the transference of the argument from the domesticated to the untamed animals. Assuming that man as the selector can do much in a limited time, Mr. Darwin argues that Nature, a more powerful, a more continuous power, working over vastly extended ranges of time, can do more. But why should Nature, so uniform and persistent in all her operations, tend in this instance to change? Why should she become a selector of varieties?63Another critic, Fleeming Jenkin, found the analogy a weakness in Darwin's theory because of the limited extent of variation in any one direction in domestic animals and plants.64 We have already seen that Darwin had confided a similar view to his notebook thirty years earlier, but changed his mind as a result of his profound study of domesticates. De Beer's reference to “an English country gentleman's knowledge of domestic plants and animals and their breeding”65 fails totally to recognize the originality and depth of Darwin's knowledge of domesticates.Why did Darwin, against the currents of his time, rely so heavily on mankind's experience with domesticated organisms to shape his theory about species in nature? On reason is that only with domesticates was an approach that came close to experimental verification possible. Darwin fully realized the inadequacies of the experiment, as is emphasized by his repeated contrasting of selection under nature and selection by man. Yet the extensive experience and data of plant and animal breeders offered the only reliable base against which Darwin could continually challenge his views. As he wrote in the introduction to Variation, with domestication, “man ... may be said to have been trying an experiment on a gigantic scale.”66 Given Darwin's high opinion of the quantitative work of Malthus and Quetelet (as emphasized by Schweber),67 and his unremitting efforts to secure data by which to test his theories, it was inevitable that he should attach high significance to domesticated varieties. John Tyndall, in his Belfast address of 1874, said: “The strength of the doctrine of Evolution consists, not in experimental demonstration (for the subject is hardly accessible to this mode of proof), but in its general harmony with scientific thought.”68 Darwin would have agreed with the latter thought, but I think he would have challenged the preceding one on the grounds that long experience with domesticated varieties did provide an element of experimental demonstration. It gave him confidence in his theory, and he used his vast knowledge of artificial selection boldly and creatively. (shrink)