13 ideas
| 15375 | If terms change their designations in different states, they are functions from states to objects [Fitting] |
| Full Idea: The common feature of every designating term is that designation may change from state to state - thus it can be formalized by a function from states to objects. | |
| From: Melvin Fitting (Intensional Logic [2007], 3) | |
| A reaction: Specifying the objects sounds OK, but specifying states sounds rather tough. |
| 15376 | Intensional logic adds a second type of quantification, over intensional objects, or individual concepts [Fitting] |
| Full Idea: To first order modal logic (with quantification over objects) we can add a second kind of quantification, over intensions. An intensional object, or individual concept, will be modelled by a function from states to objects. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.3) |
| 15378 | Awareness logic adds the restriction of an awareness function to epistemic logic [Fitting] |
| Full Idea: Awareness logic enriched Hintikka's epistemic models with an awareness function, mapping each state to the set of formulas we are aware of at that state. This reflects some bound on the resources we can bring to bear. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.6.1) | |
| A reaction: [He cites Fagin and Halpern 1988 for this] |
| 15379 | Justication logics make explicit the reasons for mathematical truth in proofs [Fitting] |
| Full Idea: In justification logics, the logics of knowledge are extended by making reasons explicit. A logic of proof terms was created, with a semantics. In this, mathematical truths are known for explicit reasons, and these provide a measure of complexity. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.6.1) |
| 18270 | Choice suggests that intensions are not needed to ensure classes [Coffa] |
| Full Idea: The axiom of choice was an assumption that implicitly questioned the necessity of intensions to guarantee the presence of classes. | |
| From: J. Alberto Coffa (The Semantic Tradition from Kant to Carnap [1991], 7 'Log') | |
| A reaction: The point is that Choice just picks out members for no particular reason. So classes, it seems, don't need a reason to exist. |
| 11026 | Classical logic is deliberately extensional, in order to model mathematics [Fitting] |
| Full Idea: Mathematics is typically extensional throughout (we write 3+2=2+3 despite the two terms having different meanings). ..Classical first-order logic is extensional by design since it primarily evolved to model the reasoning of mathematics. | |
| From: Melvin Fitting (Intensional Logic [2007], §1) |
| 11028 | λ-abstraction disambiguates the scope of modal operators [Fitting] |
| Full Idea: λ-abstraction can be used to abstract and disambiguate a predicate. De re is [λx◊P(x)](f) - f has the possible-P property - and de dicto is ◊[λxP(x)](f) - possibly f has the P-property. Also applies to □. | |
| From: Melvin Fitting (Intensional Logic [2007], §3.3) | |
| A reaction: Compare the Barcan formula. Originated with Church in the 1930s, and Carnap 1947, but revived by Stalnaker and Thomason 1968. Because it refers to the predicate, it has a role in intensional versions of logic, especially modal logic. |
| 15377 | Definite descriptions pick out different objects in different possible worlds [Fitting] |
| Full Idea: Definite descriptions pick out different objects in different possible worlds quite naturally. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.4) | |
| A reaction: A definite description can pick out the same object in another possible world, or a very similar one, or an object which has almost nothing in common with the others. |
| 18263 | The semantic tradition aimed to explain the a priori semantically, not by Kantian intuition [Coffa] |
| Full Idea: The semantic tradition's problem was the a priori; its enemy, Kantian pure intuition; its purpose, to develop a conception of the a priori in which pure intuition played no role; its strategy, to base that theory on a development of semantics. | |
| From: J. Alberto Coffa (The Semantic Tradition from Kant to Carnap [1991], 2 Intro) | |
| A reaction: It seems to me that intuition, in the modern sense, has been unnecessarily demonised. I would define it as 'rational insights which cannot be fully articulated'. Sherlock Holmes embodies it. |
| 18272 | Platonism defines the a priori in a way that makes it unknowable [Coffa] |
| Full Idea: The trouble with Platonism had always been its inability to define a priori knowledge in a way that made it possible for human beings to have it. | |
| From: J. Alberto Coffa (The Semantic Tradition from Kant to Carnap [1991], 7 'What') | |
| A reaction: This is the famous argument of Benacerraf 1973. |
| 18266 | Mathematics generalises by using variables [Coffa] |
| Full Idea: The instrument of generality in mathematics is the variable. | |
| From: J. Alberto Coffa (The Semantic Tradition from Kant to Carnap [1991], 4 'The conc') | |
| A reaction: I like the idea that there are variables in ordinary speech, pronouns being the most obvious example. 'Cats' is a variable involving quantification over a domain of lovable fluffy mammals. |
| 18279 | Relativity is as absolutist about space-time as Newton was about space [Coffa] |
| Full Idea: If the theory of relativity might be thought to support an idealist construal of space and time, it is no less absolutistic about space-time than Newton's theory was about space. | |
| From: J. Alberto Coffa (The Semantic Tradition from Kant to Carnap [1991]) | |
| A reaction: [He cites Minkowski, Weyl and Cartan for this conclusion] Coffa is clearly a bit cross about philosophers who draw naive idealist and relativist conclusions from relativity. |
| 7902 | The Buddha made flowers float in the air, to impress people, and make them listen [Mahavastu] |
| Full Idea: When the young Brahmin threw her two lotuses, they stood suspended in the air. This was one of the miracles by which the Buddhas impress people, to make them listen to the truth. | |
| From: Mahavastu (The Great Event [c.200], I.231-9) | |
| A reaction: Presumably this is the reason that Jesus did miracles. It is hard to spot the truth among the myriad of lies, if there is no supporting miracle to give authority to the speaker. |