Combining Texts

All the ideas for 'Mahaprajnaparamitashastra', 'Continuity and Irrational Numbers' and 'Rationality'

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7 ideas

6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
17611 We want the essence of continuity, by showing its origin in arithmetic [Dedekind]
     Full Idea: It then only remained to discover its true origin in the elements of arithmetic and thus at the same time to secure a real definition of the essence of continuity.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], Intro)
     A reaction: [He seeks the origin of the theorem that differential calculus deals with continuous magnitude, and he wants an arithmetical rather than geometrical demonstration; the result is his famous 'cut'].
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / i. Reals from cuts
10572 A cut between rational numbers creates and defines an irrational number [Dedekind]
     Full Idea: Whenever we have to do a cut produced by no rational number, we create a new, an irrational number, which we regard as completely defined by this cut.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], §4)
     A reaction: Fine quotes this to show that the Dedekind Cut creates the irrational numbers, rather than hitting them. A consequence is that the irrational numbers depend on the rational numbers, and so can never be identical with any of them. See Idea 10573.
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / f. Arithmetic
17612 Arithmetic is just the consequence of counting, which is the successor operation [Dedekind]
     Full Idea: I regard the whole of arithmetic as a necessary, or at least natural, consequence of the simplest arithmetic act, that of counting, and counting itself is nothing else than the successive creation of the infinite series of positive integers.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], §1)
     A reaction: Thus counting roots arithmetic in the world, the successor operation is the essence of counting, and the Dedekind-Peano axioms are built around successors, and give the essence of arithmetic. Unfashionable now, but I love it. Intransitive counting?
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / l. Limits
18087 If x changes by less and less, it must approach a limit [Dedekind]
     Full Idea: If in the variation of a magnitude x we can for every positive magnitude δ assign a corresponding position from and after which x changes by less than δ then x approaches a limiting value.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], p.27), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.7
     A reaction: [Kitcher says he 'showed' this, rather than just stating it]
12. Knowledge Sources / E. Direct Knowledge / 4. Memory
23304 The ancient Memorists said virtually all types of thinking could be done simply by memory [Sorabji]
     Full Idea: The ancient medical Memorists said that ordinary thinking, inferring, reflecting, believing, assuming, examining, generalising and knowing can all be done simply on the basis of memory.
     From: Richard Sorabji (Rationality [1996], 'Inference')
     A reaction: The think there is a plausible theory that all neurons do is remember, and are mainly distinguished by the duration of their memories. We might explain these modes of thinking in terms of various combinations of the fast and the slow.
23303 Stoics say true memory needs reflection and assent, but animals only have perceptual recognition [Sorabji]
     Full Idea: Stoics say memory proper involves reflection and assent. Animal memory, by contrast, is not memory proper, but mere perceptual recognition. The horse remembers the road when he is on it, but not when he is in the stable.
     From: Richard Sorabji (Rationality [1996], 'Other')
     A reaction: An interesting distinction. Do I remember something if I can never recall it, and yet recognise it when it reappears, such as a person I knew long ago? 'Memory' is ambiguous, between lodged in the mind, and recallable. Unfair to horses, this.
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
7903 The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna]
     Full Idea: The six perfections are of giving, morality, patience, vigour, meditation, and wisdom.
     From: Nagarjuna (Mahaprajnaparamitashastra [c.120], 88)
     A reaction: What is 'morality', if giving is not part of it? I like patience and vigour being two of the virtues, which immediately implies an Aristotelian mean (which is always what is 'appropriate').