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如果你也在线性代数linearalgebra这个学科遇到相关的难题,请随时添加vx号联系我们的代写客服。我们会为你提供专业的服务。 linearalgebra™长期致力于留学生网课服务,涵盖各个网络学科课程:金融学Finance,经济学Economics,数学Mathematics,会计Accounting,文学Literature,艺术Arts等等。除了网课全程托管外,linearalgebra™也可接受单独网课任务。无论遇到了什么网课困难,都能帮你完美解决! PrefaceMathematical Logic is a necessary preliminary to logical Mathematics. “Mathematical Logic” is the name given by Peano to what is also known (after Venn ) as “Symbolic Logic”; and Symbolic Logic is, in essentials, the Logic of Aristotle, given new life and power by being dressed up in the wonderful–almost magical–armour and accoutrements of Algebra. In less than seventy years, logic, to use an expression of De Morgan’s, has so _thriven_ upon symbols and, in consequence, so grown and altered that the ancient logicians would not recognize it, and many old-fashioned logicians will not recognize it. The metaphor is not quite correct: Logic has neither grown nor altered, but we now see more _of_ it and more _into_ it.The primary significance of a symbolic calculus seems to lie in the economy of mental effort which it brings about, and to this is due the characteristic power and rapid development of mathematical knowledge. Attempts to treat the operations of formal logic in an analogous way had been made not infrequently by some of the more philosophical mathematicians, such as Leibniz and Lambert ; but their labors remained little known, and it was Boole and De Morgan, about the middle of the nineteenth century, to whom a mathematical–though of course non-quantitative–way of regarding logic was due. By this, not only was the traditional or Aristotelian doctrine of logic reformed and completed, but out of it has developed, in course of time, an instrument which deals in a sure manner with the task of investigating the fundamental concepts of mathematics–a task which philosophers have repeatedly taken in hand, and in which they have as repeatedly failed.First of all, it is necessary to glance at the growth of symbolism in mathematics; where alone it first reached perfection. There have been three stages in the development of mathematical doctrines: first came propositions with particular numbers, like the one expressed, with signs subsequently invented, by “\(2+3=5\)”; then came more general laws holding for all numbers and expressed by letters, such as\[“(a+b)c=ac+bc”;\]lastly came the knowledge of more general laws of functions and the formation of the conception and expression “function”. The origin of the symbols for particular whole numbers is very ancient, while the symbols now in use for the operations and relations of arithmetic mostly date from the sixteenth and seventeenth centuries; and these “constant” symbols together with the letters first used systematically by Viete (1540-1603) and Descartes (1596-1650), serve, by themselves, to express many propositions. It is not, then, surprising that Descartes, who was both a mathematician and a philosopher, should have had the idea of keeping the method of algebra while going beyond the material of traditional mathematics and embracing the general science of what thought finds, so that philosophy should become a kind of Universal Mathematics. This sort of generalization of the use of symbols for analogous theories is a characteristic of mathematics, and seems to be a reason lying deeper than theerroneous idea, arising from a simple confusion of thought, that algebraical symbols necessarily imply something quantitative, for the antagonism there used to be and is on the part of those logicians who were not and are not mathematicians, to symbolic logic. This idea of a universal mathematics was cultivated especially by Gottfried Wilhelm Leibniz (1646-1716).Though modern logic is really due to Boole and De Morgan, Leibniz was the first to have a really distinct plan of a system of mathematical logic. That this is so appears from research–much of which is quite recent–into Leibniz’s unpublished work.The principles of the logic of Leibniz, and consequently of his whole philosophy, reduce to two1: (1) All our ideas are compounded of a very small number of simple ideas which form the “alphabet of human thoughts”; (2) Complex ideas proceed from these simple ideas by a uniform and symmetrical combination which is analogous to arithmetical multiplication. With regard to the first principle, the number of simple ideas is much greater than Leibniz thought; and, with regard to the second principle, logic considers three operations–which we shall meet with in the following book under the names of logical multiplication, logical addition and negation–instead of only one.Courturat, La Logique de Leibniz d’apres des documents indéits, Paris, 1901, pp. 431-432, 48.”Characters” were, with Leibniz, any written signs, and “real” characters were those which–as in the Chinese ideography–represent ideas directly, and not the words for them. Among real characters, some simply serve to represent ideas, and some serve for reasoning. Egyptian and Chinese hieroglyphics and the symbols of astronomers and chemists belong to the first category, but Leibniz declared them to be imperfect, and desired the second category of characters for what he called his “universal characteristic”.2 It was not in the form of an algebra that Leibniz first conceived his characteristic, probably because he was then a novice in mathematics, but in the form of a universal language or script.3 It was in 1676 that he first dreamed of a kind of algebra of thought,4 and it was the algebraic notation which then served as model for the characteristic.5Ibid., p. 81.Ibid., pp. 51, 78Ibid., p. 61.Ibid., p. 83.Ibid., p. 84.Ibid., p. 84.Leibniz attached so much importance to the invention of proper symbols that he attributed to this alone the whole of his discoveries in mathematics.6 And, in fact, his infinitesimal calculus affords a most brilliant example of the importance of, and Leibniz’ s skill in devising, a suitable notation.7Ibid., p. 84.Now, it must be remembered that what is usually understood by the name “symbolic logic”, and which–though not its name–is chiefly due to Boole, is what Leibniz called a _Calculus ratiocinator_, and is only a part of the Universal Characteristic. In symbolic logic Leibniz enunciated the principal properties of what we now call logical multiplication, addition, negation, identity, class-inclusion, and the null-class; but the aim of Leibniz’s researches was, as he said, to create “a kind of general system of notation in which all the truths of reason should be reduced to a calculus. This could be, at the same time, a kind of universal written language, very different from all those which have been projected hitherto; for the characters and even the words would direct the reason, and the errors–excepting those of fact–would only be errors of calculation. It would be very difficult to invent this language or characteristic, but very easy to learn it without any dictionaries”. He fixed the time necessary to form it: “I think that some chosen men could finish the matter within five years”; and finally remarked: “And so I repeat, what I have often said, that a man who is neither a prophet nor a prince can never undertake any thing more conducive to the good of the human race and the glory of God”.In his last letters he remarked: “If I had been less busy, or if I were younger or helped by well-intentioned young people, I would have hoped to have evolved a characteristic of this kind”; and: “I have spoken of my general characteristic to the Marquis de l’Hopital and others; but they paid no more attention than if I had been telling them a dream图片描述

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