Combining Philosophers

All the ideas for Augustin-Louis Cauchy, Gerhard Gentzen and Buddha (Siddhartha Gautama)

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11 ideas

5. Theory of Logic / A. Overview of Logic / 2. History of Logic
Gentzen introduced a natural deduction calculus (NK) in 1934 [Gentzen, by Read]
     Full Idea: Gentzen introduced a natural deduction calculus (NK) in 1934.
     From: report of Gerhard Gentzen (works [1938]) by Stephen Read - Thinking About Logic Ch.8
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
The inferential role of a logical constant constitutes its meaning [Gentzen, by Hanna]
     Full Idea: Gentzen argued that the inferential role of a logical constant constitutes its meaning.
     From: report of Gerhard Gentzen (works [1938]) by Robert Hanna - Rationality and Logic 5.3
     A reaction: Possibly inspired by Wittgenstein's theory of meaning as use? This idea was the target of Prior's famous connective 'tonk', which has the role of implying anything you like, proving sentences which are not logical consequences.
The logical connectives are 'defined' by their introduction rules [Gentzen]
     Full Idea: The introduction rules represent, as it were, the 'definitions' of the symbols concerned, and the elimination rules are no more, in the final analysis, than the consequences of these definitions.
     From: Gerhard Gentzen (works [1938]), quoted by Stephen Read - Thinking About Logic Ch.8
     A reaction: If an introduction-rule (or a truth table) were taken as fixed and beyond dispute, then it would have the status of a definition, since there would be nothing else to appeal to. So is there anything else to appeal to here?
Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen]
     Full Idea: To every logical symbol there belongs precisely one inference figure which 'introduces' the symbol ..and one which 'eliminates' it. The introductions represent the 'definitions' of the symbols concerned, and eliminations are consequences of these.
     From: Gerhard Gentzen (works [1938], II.5.13), quoted by Ian Rumfitt - "Yes" and "No" III
     A reaction: [1935 paper] This passage is famous, in laying down the basics of natural deduction systems of logic (ones using only rules, and avoiding axioms). Rumfitt questions whether Gentzen's account gives the sense of the connectives.
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
Natural deduction shows the heart of reasoning (and sequent calculus is just a tool) [Gentzen, by Hacking]
     Full Idea: Gentzen thought that his natural deduction gets at the heart of logical reasoning, and used the sequent calculus only as a convenient tool for proving his chief results.
     From: report of Gerhard Gentzen (Investigations into Logical Deduction [1935]) by Ian Hacking - What is Logic? §05
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / k. Infinitesimals
Values that approach zero, becoming less than any quantity, are 'infinitesimals' [Cauchy]
     Full Idea: When the successive absolute values of a variable decrease indefinitely in such a way as to become less than any given quantity, that variable becomes what is called an 'infinitesimal'. Such a variable has zero as its limit.
     From: Augustin-Louis Cauchy (Cours d'Analyse [1821], p.19), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.4
     A reaction: The creator of the important idea of the limit still talked in terms of infinitesimals. In the next generation the limit took over completely.
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / l. Limits
When successive variable values approach a fixed value, that is its 'limit' [Cauchy]
     Full Idea: When the values successively attributed to the same variable approach indefinitely a fixed value, eventually differing from it by as little as one could wish, that fixed value is called the 'limit' of all the others.
     From: Augustin-Louis Cauchy (Cours d'Analyse [1821], p.19), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.4
     A reaction: This seems to be a highly significan proposal, because you can now treat that limit as a number, and adds things to it. It opens the door to Cantor's infinities. Is the 'limit' just a fiction?
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
Gentzen proved the consistency of arithmetic from assumptions beyond arithmetic [Gentzen, by Musgrave]
     Full Idea: Gentzen proved the consistency of arithmetic from assumptions which transcend arithmetic.
     From: report of Gerhard Gentzen (works [1938]) by Alan Musgrave - Logicism Revisited §5
     A reaction: This does not contradict Gödel's famous result, but reinforces it. The interesting question is what assumptions Gentzen felt he had to make.
16. Persons / E. Rejecting the Self / 4. Denial of the Self
Individuals don't exist, but are conventional names for sets of elements [Buddha]
     Full Idea: There exists no individual, it is only a conventional name given to a set of elements.
     From: Buddha (Siddhartha Gautama) (reports [c.540 BCE]), quoted by Derek Parfit - The Unimportance of Identity p.295
     A reaction: I take this to arise from an excessively spiritual concept of a human being, which faces Descartes' problem of how to individuate non-physical minds, when they have no clear boundaries. Combine dualism with a bundle theory, and you have Buddhism.
29. Religion / C. Spiritual Disciplines / 3. Buddhism
The Buddha believed the gods would eventually disappear, and Nirvana was much higher [Buddha, by Armstrong,K]
     Full Idea: The Buddha believed implicitly in the gods because they were part of his cultural baggage, but they were involved in the cycle of rebirth, and would eventually disappear; the ultimate reality of Nirvana was higher than the gods.
     From: report of Buddha (Siddhartha Gautama) (reports [c.540 BCE]) by Karen Armstrong - A History of God Ch.1
     A reaction: We might connect this with Plato's Euthyphro question (Ideas 336 and 337), and the relationship between piety and morality on the one hand, and the gods on the other.
Life is suffering, from which only compassion, gentleness, truth and sobriety can save us [Buddha]
     Full Idea: Buddha taught that the only release from 'dukkha' (the meaningless flux of suffering which is human life) is a life of compassion for all living beings, speaking and behaving gently, kindly and accurately, and refraining from all intoxicants.
     From: Buddha (Siddhartha Gautama) (reports [c.540 BCE], Ch.1), quoted by Karen Armstrong - A History of God Ch.1
     A reaction: Christians are inclined to give the impression that Jesus invented the idea of being nice, but it ain't so. The obvious thought is that the Buddha seems to be focusing on the individual, but this is actually a formula for a better community.