14 ideas
13831 | Logic is based on transitions between sentences [Prawitz] |
Full Idea: I agree entirely with Dummett that the right way to answer the question 'what is logic?' is to consider transitions between sentences. | |
From: Dag Prawitz (Gentzen's Analysis of First-Order Proofs [1974], §04) | |
A reaction: I always protest at this point that reliance on sentences is speciesism against animals, who are thereby debarred from reasoning. See the wonderful Idea 1875 of Chrysippus. Hacking's basic suggestion seems right. Transition between thoughts. |
13825 | Natural deduction introduction rules may represent 'definitions' of logical connectives [Prawitz] |
Full Idea: With Gentzen's natural deduction, we may say that the introductions represent, as it were, the 'definitions' of the logical constants. The introductions are not literally understood as 'definitions'. | |
From: Dag Prawitz (Gentzen's Analysis of First-Order Proofs [1974], 2.2.2) | |
A reaction: [Hacking, in 'What is Logic? §9' says Gentzen had the idea that his rules actually define the constants; not sure if Prawitz and Hacking are disagreeing] |
13823 | In natural deduction, inferences are atomic steps involving just one logical constant [Prawitz] |
Full Idea: In Gentzen's natural deduction, the inferences are broken down into atomic steps in such a way that each step involves only one logical constant. The steps are the introduction or elimination of the logical constants. | |
From: Dag Prawitz (Gentzen's Analysis of First-Order Proofs [1974], 1.1) |
19451 | When absorbed in deep reflection, is your reason in control, or is it you? [Feuerbach] |
Full Idea: When, submerged in deep reflection, you forget both yourself and your surroundings, is it you who controls reason, or is it rather reason that controls and absorbs you? | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], I) | |
A reaction: A delightful question, even if it looks like a false dichotomy. I'm not sure what to make of 'me', if my reason can be subtracted from it. Aquinas was one the same wavelength here. |
6000 | The goal is rationality in the selection of things according to nature [Diogenes of Babylon, by Blank] |
Full Idea: Diogenes of Babylon defined the goal to be rationality in the selection and rejection of the things according to nature. | |
From: report of Diogenes (Bab) (fragments/reports [c.180 BCE]) by D.L. Blank - Diogenes of Babylon | |
A reaction: This captures the central Stoic idea quite nicely. 'Live according to nature', but this always meant 'live according to reason', because that is (as Aristotle had taught) the essence of our nature. This only makes sense if reason and nature coincide. |
5999 | The good is what is perfect by nature [Diogenes of Babylon, by Blank] |
Full Idea: Diogenes of Babylon defined the good as what is perfect by nature. | |
From: report of Diogenes (Bab) (fragments/reports [c.180 BCE]) by D.L. Blank - Diogenes of Babylon | |
A reaction: This might come close to G.E. Moore's Ideal Utilitarianism, but its dependence on the rather uneasy of concept of 'perfection' makes it questionable. Personally I find it appealing. I wish we had Diogenes' explanation. |
19450 | Reason, love and will are the highest perfections and essence of man - the purpose of his life [Feuerbach] |
Full Idea: Reason, love and power of will are perfections of man; they are his highest powers, his absolute essence in so far as he is man, the purpose of his existence. Man exists in order to think, love and will. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], I) | |
A reaction: Feuerbach was a notable atheist, but adopts a religious style of language which modern atheists would find rather alien. Personally I love talk of ideals and perfections. Ideals have been discredited in modern times, but need a revival. |
6001 | Justice is a disposition to distribute according to desert [Diogenes of Babylon, by Blank] |
Full Idea: Diogenes of Babylon defined justice as the disposition which distributes to everyone what he deserves. | |
From: report of Diogenes (Bab) (fragments/reports [c.180 BCE]) by D.L. Blank - Diogenes of Babylon | |
A reaction: The questions that arise would be 'what does a new-born baby deserve?', and 'what do animals deserve?', and 'does the lowest and worst of criminals deserve anything at all?' |
19448 | Consciousness is said to distinguish man from animals - consciousness of his own species [Feuerbach] |
Full Idea: What constitutes the essential difference between man and animal? The most simple, general, and most widely held answer to this question is consciousness. Consciousness is given only in the case of a being to whom his species ...is an object of thought. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], I) | |
A reaction: Rather speculative. Since other species cohabit and breed only with their fellow species members, one might have thought they were aware of them. |
19454 | A God needs justice, kindness and wisdom, but those concepts don't depend on the concept of God [Feuerbach] |
Full Idea: The concept of God depends on the concepts of justice, kindness and wisdom - a God who is not kind, not just, and not wise is no God. But these concepts do not depend on the concept of God. That a quality is possessed by God does not make it divine. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], II) | |
A reaction: This is part of Feuerbach's argument for atheism, but if you ask for the source of our human concepts of justice, kindness and wisdom, no one, I would have thought, could cite God for the role. |
19452 | The nature of God is an expression of human nature [Feuerbach] |
Full Idea: God is the manifestation of man's inner nature, his expressed self. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], II) | |
A reaction: Even if you are a deeply committed theist, you have to concede some of this point. The perfections attributed to God are usually of human qualities. Leibniz, though, says that God has an infinity of perfection, mostly unknown to us. |
19453 | If love, goodness and personality are human, the God who is their source is anthropomorphic [Feuerbach] |
Full Idea: If love, goodness, and personality are human determinations, the being which constitutes their source and ...their presupposition is also an anthropomorphism; so is the existence of God. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], II) | |
A reaction: It is certainly a struggle for the imagination to grasp a being which is characterised by idealised versions of human virtues, and yet has an intrinsic nature which is utterly different from humanity. |
19449 | Religion is the consciousness of the infinite [Feuerbach] |
Full Idea: Religion is the consciousness of the infinite. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], I) |
19455 | Today's atheism will tomorrow become a religion [Feuerbach] |
Full Idea: What is regarded as atheism today will be religion tomorrow. | |
From: Ludwig Feuerbach (Introduction of 'Essence of Christianity' [1841], II) | |
A reaction: Modern critics of atheism frequently accuse it of being a new religion. I doubt whether Feuerbach is right, but it is a nice provocative idea. |