11 ideas
| 7823 | Lucretius was rediscovered in 1417 [Grayling] |
| Full Idea: Lucretius's 'De Rerum Natura' was rediscovered in 1417, after languishing forgotten for six centuries. | |
| From: A.C. Grayling (What is Good? [2003], Ch.5) | |
| A reaction: A wonder. Is it the greatest book of the ancient world - because it partially preserves the lost philosophy of great Democritus? |
| 18812 | Split out the logical vocabulary, make an assignment to the rest. It's logical if premises and conclusion match [Tarski, by Rumfitt] |
| Full Idea: Tarski made a division of logical and non-logical vocabulary. He then defined a model as a non-logical assignment satisfying the corresponding sentential function. Then a conclusion follows logically if every model of the premises models the conclusion. | |
| From: report of Alfred Tarski (The Concept of Logical Consequence [1936]) by Ian Rumfitt - The Boundary Stones of Thought 3.2 | |
| A reaction: [compressed] This is Tarski's account of logical consequence, which follows on from his account of truth. 'Logical validity' is then 'true in every model'. Rumfitt doubts whether Tarski has given the meaning of 'logical consequence'. |
| 13344 | X follows from sentences K iff every model of K also models X [Tarski] |
| Full Idea: The sentence X follows logically from the sentences of the class K if and only if every model of the class K is also a model of the sentence X. | |
| From: Alfred Tarski (The Concept of Logical Consequence [1936], p.417) | |
| A reaction: [see Idea 13343 for his account of a 'model'] He is offering to define logical consequence in general, but this definition fits what we now call 'semantic consequence', written |=. This it is standard practice to read |= as 'models'. |
| 13343 | A 'model' is a sequence of objects which satisfies a complete set of sentential functions [Tarski] |
| Full Idea: An arbitrary sequence of objects which satisfies every sentential function of the sentences L' will be called a 'model' or realization of the class L of sentences. There can also be a model of a single sentence is this way. | |
| From: Alfred Tarski (The Concept of Logical Consequence [1936], p.417) | |
| A reaction: [L' is L with the constants replaced by variables] Tarski is the originator of model theory, which is central to modern logic. The word 'realization' is a helpful indicator of what he has in mind. A model begins to look like a possible world. |
| 13345 | Sentences are 'analytical' if every sequence of objects models them [Tarski] |
| Full Idea: A class of sentences can be called 'analytical' if every sequence of objects is a model of it. | |
| From: Alfred Tarski (The Concept of Logical Consequence [1936], p.418) | |
| A reaction: See Idea 13344 and Idea 13343 for the context of this assertion. |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
| Full Idea: In singing and playing the lyre, a boy will be likely to reveal not only courage and moderation, but also justice. | |
| From: Damon (fragments/reports [c.460 BCE], B4), quoted by (who?) - where? |
| 7809 | In an honour code shame is the supreme punishment, and revenge is a duty [Grayling] |
| Full Idea: An honour code is one in which the greatest punishment is shame, and in which revenge is a duty. | |
| From: A.C. Grayling (What is Good? [2003], Ch.2) | |
| A reaction: Is this really what Nietzsche wanted to revive? Shame isn't a private matter - it needs solidarity of values in the community, and contempt for dishonour, so that it becomes everyone's worst fear. |
| 7824 | If suicide is lawful, but assisting suicide is unlawful, powerless people are denied their rights [Grayling] |
| Full Idea: An anomaly created by England's 1961 Suicide Act is that it is lawful to take one's own life, but unlawful to help anyone else to do it. This means anyone unable to commit suicide without help is denied one of their fundamental rights. | |
| From: A.C. Grayling (What is Good? [2003], Ch.8) | |
| A reaction: There is a difference, not really captured either by law or by reason, between tolerating an activity, and encouraging and helping it. I think the test question is "this activity is legal, but would you want your child to do it?" |
| 7819 | Religion gives answers, comforts, creates social order, and panders to superstition [Grayling] |
| Full Idea: The four standard explanations given for religion are that it provides answer, that it gives comfort, that it makes for social order, and that it rests on mere superstition. | |
| From: A.C. Grayling (What is Good? [2003], Ch.4) | |
| A reaction: All four of these could be correct, though the first and fourth would be incompatible if religion gives correct answers. Why religion begins might be not the same as the reason why it continues. |
| 7817 | To make an afterlife appealing, this life has to be denigrated [Grayling] |
| Full Idea: It is remarkable how much the life of this world has to be denigrated to make the promise of happiness after death appealing. | |
| From: A.C. Grayling (What is Good? [2003], Ch.4) | |
| A reaction: This seems to be true of most religions, but it could be otherwise. Surely you want such a wonderful life to continue after death? But then you would not be obliged to do anything difficult to achieve immortality. Power comes into it... |
| 7818 | In Greek mythology only heroes can go to heaven [Grayling] |
| Full Idea: In Greek mythology only a hero like Hercules could hope to go to heaven (by becoming a god himself). | |
| From: A.C. Grayling (What is Good? [2003], Ch.4) | |
| A reaction: This illustrates Nietsche's 'inversion of morality' most clearly, because Christianity says that the person most likely to go to heaven is the humblest person. |