18 ideas
| 343 | The unexamined life is not worth living for men [Socrates] |
| Full Idea: The unexamined life is not worth living for men. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 38a | |
| A reaction: I wonder why? I can see Nietzsche offering aristocratic heroes and dancers as counterexamples. Compare Idea 3798. |
| 13338 | '"It is snowing" is true if and only if it is snowing' is a partial definition of the concept of truth [Tarski] |
| Full Idea: Statements of the form '"it is snowing" is true if and only if it is snowing' and '"the world war will begin in 1963" is true if and only if the world war will being in 1963' can be regarded as partial definitions of the concept of truth. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.404) | |
| A reaction: The key word here is 'partial'. Truth is defined, presumably, when every such translation from the object language has been articulated, which is presumably impossible, given the infinity of concatenated phrases possible in a sentence. |
| 13337 | A language: primitive terms, then definition rules, then sentences, then axioms, and finally inference rules [Tarski] |
| Full Idea: For a language, we must enumerate the primitive terms, and the rules of definition for new terms. Then we must distinguish the sentences, and separate out the axioms from amng them, and finally add rules of inference. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.402) | |
| A reaction: [compressed] This lays down the standard modern procedure for defining a logical language. Once all of this is in place, we then add a semantics and we are in business. Natural deduction tries to do without the axioms. |
| 13335 | Semantics is the concepts of connections of language to reality, such as denotation, definition and truth [Tarski] |
| Full Idea: Semantics is the totality of considerations concerning concepts which express connections between expressions of a language and objects and states of affairs referred to by these expressions. Examples are denotation, satisfaction, definition and truth. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.401) | |
| A reaction: Interestingly, he notes that it 'is not commonly recognised' that truth is part of semantics. Nowadays truth seems to be the central concept in most semantics. |
| 13336 | A language containing its own semantics is inconsistent - but we can use a second language [Tarski] |
| Full Idea: People have not been aware that the language about which we speak need by no means coincide with the language in which we speak. ..But the language which contains its own semantics must inevitably be inconsistent. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.402) | |
| A reaction: It seems that Tarski was driven to propose the metalanguage approach mainly by the Liar Paradox. |
| 13339 | A sentence is satisfied when we can assert the sentence when the variables are assigned [Tarski] |
| Full Idea: Here is a partial definition of the concept of satisfaction: John and Peter satisfy the sentential function 'X and Y are brothers' if and only if John and Peter are brothers. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.405) | |
| A reaction: Satisfaction applies to open sentences and truth to closed sentences (with named objects). He uses the notion of total satisfaction to define truth. The example is a partial definition, not just an illustration. |
| 13340 | Satisfaction is the easiest semantical concept to define, and the others will reduce to it [Tarski] |
| Full Idea: It has been found useful in defining semantical concepts to deal first with the concept of satisfaction; both because the definition of this concept presents relatively few difficulties, and because the other semantical concepts are easily reduced to it. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.406) | |
| A reaction: See Idea 13339 for his explanation of satisfaction. We just say that a open sentence is 'acceptable' or 'assertible' (or even 'true') when particular values are assigned to the variables. Then sentence is then 'satisfied'. |
| 13341 | Using the definition of truth, we can prove theories consistent within sound logics [Tarski] |
| Full Idea: Using the definition of truth we are in a position to carry out the proof of consistency for deductive theories in which only (materially) true sentences are (formally) provable. | |
| From: Alfred Tarski (The Establishment of Scientific Semantics [1936], p.407) | |
| A reaction: This is evidently what Tarski saw as the most important first fruit of his new semantic theory of truth. |
| 339 | Men fear death as a great evil when it may be a great blessing [Socrates] |
| Full Idea: No one knows whether death may not be the greatest of all blessings for a man, yet men fear it as if they knew that it is the greatest of evils. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 29a | |
| A reaction: As a neutral observer, I see little sign of it being a blessing, except as a relief from misery. It seem wrong to view such a natural thing as evil, but it is the thing most of us least desire. |
| 344 | If death is like a night of dreamless sleep, such nights are very pleasant [Socrates] |
| Full Idea: If death is like a night of dreamless sleep it is an advantage, for such nights are very pleasant, and eternity would seem like a single night. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 40d | |
| A reaction: Dreamless sleep is only pleasant if being awake is unpleasant. Very quiet days are only pleasant if the active days are horrible. A desire for a totally quiet life is absurd. |
| 2 | We should not even harm someone who harms us [Socrates] |
| Full Idea: One should never return an injustice nor harm another human being no matter what one suffers at their hands. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - Crito 49c | |
| A reaction: Jesus of Nazareth was not the first person to make this suggestion. |
| 345 | A good man cannot be harmed, either in life or in death [Socrates] |
| Full Idea: A good man cannot be harmed, either in life or in death. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 41d |
| 346 | One ought not to return a wrong or injury to any person, whatever the provocation [Socrates] |
| Full Idea: One ought not to return a wrong or an injury to any person, whatever the provocation is. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - Crito 49b | |
| A reaction: The same as the essential moral teachings of Jesus (see Idea 6288) and Lao Tzu (Idea 6324). The big target is not to be corrupted by the evil of other people. |
| 341 | Wealth is good if it is accompanied by virtue [Socrates] |
| Full Idea: Wealth does not bring about excellence, but excellence makes wealth and everything else good for men. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 30b |
| 347 | Will I stand up against the law, simply because I have been unjustly judged? [Socrates] |
| Full Idea: Do I intend to destroy the laws, because the state wronged me by passing a faulty judgement at my trial? | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - Crito 50c |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes. | |
| From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078 | |
| A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book. |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
| Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
| From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
| A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |
| 338 | Socrates is accused of denying the gods, saying sun is stone and moon is earth [Socrates, by Plato] |
| Full Idea: Socrates denies the gods, because he says the sun is stone and the moon is earth. | |
| From: report of Socrates (reports of last days [c.399 BCE]) by Plato - The Apology 26d |