5 ideas
| 14181 | Validity is where either the situation or the interpretation blocks true premises and false conclusion [Etchemendy, by Read] |
| Full Idea: The Representational account of validity says an argument is valid if there is no situation where the premises are true and the conclusion false. The Interpretation account says the premises are true and conclusion false under no interpretations. | |
| From: report of John Etchemendy (The Concept of Logical Consequence [1999]) by Stephen Read - Formal and Material Consequence 'Inval' | |
| A reaction: My immediate instinct is to want logic to be about situations, rather than interpretations. Situations are more about thought, where interpretations are more about language. I think our account of logic should have some applicability to animals. |
| 14180 | Etchemendy says fix the situation and vary the interpretation, or fix interpretations with varying situations [Etchemendy, by Read] |
| Full Idea: In Etchemendy's Interpretational Semantics (perhaps better called 'Substitutional') we keep the situation fixed and vary the interpretation; in Representational Semantics ('Modal'?) we keep interpretations fixed but consider varying situations. | |
| From: report of John Etchemendy (The Concept of Logical Consequence [1999]) by Stephen Read - Formal and Material Consequence 'Inval' | |
| A reaction: [compressed] These are semantic strategies for interpreting logic, so they are two ways you might go about assessing an argument. |
| 10558 | Abstract objects are actually constituted by the properties by which we conceive them [Zalta] |
| Full Idea: Where for ordinary objects one can discover the properties they exemplify, abstract objects are actually constituted or determined by the properties by which we conceive them. I use the technical term 'x encodes F' for this idea. | |
| From: Edward N. Zalta (Deriving Kripkean Claims with Abstract Objects [2006], 2 n2) | |
| A reaction: One might say that whereas concrete objects can be dubbed (in the Kripke manner), abstract objects can only be referred to by descriptions. See 10557 for more technicalities about Zalta's idea. |
| 10557 | Abstract objects are captured by second-order modal logic, plus 'encoding' formulas [Zalta] |
| Full Idea: My object theory is formulated in a 'syntactically second-order' modal predicate calculus modified only so as to admit a second kind of atomic formula ('xF'), which asserts that object x 'encodes' property F. | |
| From: Edward N. Zalta (Deriving Kripkean Claims with Abstract Objects [2006], p.2) | |
| A reaction: This is summarising Zalta's 1983 theory of abstract objects. See Idea 10558 for Zalta's idea in plain English. |
| 12709 | Motion is not absolute, but consists in relation [Leibniz] |
| Full Idea: In reality motion is not something absolute, but consists in relation. | |
| From: Gottfried Leibniz (On Motion [1677], A6.4.1968), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3 | |
| A reaction: It is often thought that motion being relative was invented by Einstein, but Leibniz wholeheartedly embraced 'Galilean relativity', and refused to even consider any absolute concept of motion. Acceleration is a bit trickier than velocity. |