7 ideas
| 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. |
| 15677 | Moral right is linked to validity and truth, so morality is a matter of knowledge, not an expression of values [Habermas, by Finlayson] |
| Full Idea: According to discourse ethics moral rightness is internally linked to validity and is analogous to truth: ..thus Habermas takes himself to have shown that morality is a matter of knowledge, rather than the expression of contingently held values. | |
| From: report of Jürgen Habermas (Moral Consciousness and Communicative Action [1990]) by James Gordon Finlayson - Habermas Ch.7:102 | |
| A reaction: I can immediately hear Nietzsche asking why you place such a high value on knowledge. Personally I don't assume that values must be 'contingent'. The Aristotelian tradition sees necessary values in facts about human nature. |
| 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? |
| 15671 | Move from individual willing of a general law, to willing norms agreed with other people [Habermas] |
| Full Idea: The emphasis shifts from what each can will without contradiction to be a general law, to what all can will in agreement to be a universal norm. | |
| From: Jürgen Habermas (Moral Consciousness and Communicative Action [1990], p.67), quoted by James Gordon Finlayson - Habermas Ch.5:69 | |
| A reaction: This strikes me as being very close to Scanlon's contractualism. As expressed here, it sounds more vulnerable than Kant's full universality to the problem of Nazis agreeing odious universal norms. Habermas calls it 'discourse ethics'. |