6 ideas
| 14238 | A class is an aggregate of objects; if you destroy them, you destroy the class; there is no empty class [Frege] |
| Full Idea: A class consists of objects; it is an aggregate, a collective unity, of them; if so, it must vanish when these objects vanish. If we burn down all the trees of a wood, we thereby burn down the wood. Thus there can be no empty class. | |
| From: Gottlob Frege (Elucidation of some points in E.Schröder [1895], p.212), quoted by Oliver,A/Smiley,T - What are Sets and What are they For? | |
| A reaction: This rests on Cantor's view of a set as a collection, rather than on Dedekind, which allows null and singleton sets. |
| 13856 | Conditionals are truth-functional, but we must take care with misleading ones [Grice, by Edgington] |
| Full Idea: Grice argued that the truth-functional account of conditionals can withstand objections, provided that we are careful to distinguish the false from the misleadingly true. | |
| From: report of H. Paul Grice (Logic and Conversation [1975]) by Dorothy Edgington - Do Conditionals Have Truth Conditions? 2 |
| 8948 | The odd truth table for material conditionals is explained by conversational conventions [Grice, by Fisher] |
| Full Idea: According to Grice, it is the rules that govern conversation beyond the merely logical that account for the counter-intuitiveness of the truth table for the material conditional. | |
| From: report of H. Paul Grice (Logic and Conversation [1975]) by Jennifer Fisher - On the Philosophy of Logic 8.I | |
| A reaction: There is a conversational rule which says that replies should normally relevant to context. It would be nice if logical implications were also relevant to context. |
| 13767 | Conditionals might remain truth-functional, despite inappropriate conversational remarks [Edgington on Grice] |
| Full Idea: Grice defended the truth-functional account of conditionals, noting the gap between what we are justified in believing and what is appropriate to say. .But the problem arises at the level of belief, not at the level of inappropriate conversational remarks | |
| From: comment on H. Paul Grice (Logic and Conversation [1975]) by Dorothy Edgington - Conditionals 17.1.3 |
| 14277 | A person can be justified in believing a proposition, though it is unreasonable to actually say it [Grice, by Edgington] |
| Full Idea: Grice drew attention to situations in which a person is justified in believing a proposition, which would nevertheless by an unreasonable thing for the person to say, in normal circumstances. I think he is right about disjunction and negated conjunctions. | |
| From: report of H. Paul Grice (Logic and Conversation [1975]) by Dorothy Edgington - Conditionals (Stanf) 2.4 | |
| A reaction: Edgington considers Grice's ideas of implicature as of permanent value, especially as a clarification of 1950s ordinary language philosophy. |
| 19384 | Space and time are the order of all possibilities, and don't just relate to what is actual [Leibniz] |
| Full Idea: Space and time taken together constitute the order of possibilities of the one entire universe, so that these orders relate not only to what actually is, but also to anything that could be put in its place. | |
| From: Gottfried Leibniz (Reply to 'Rorarius' 2nd ed [1702], GP iv 568), quoted by Richard T.W. Arthur - Leibniz 7 'Space and Time' | |
| A reaction: A very nice idea. Rather like the 'space of reasons', where all rational thought must exist, space and time are the 'space of existence and action'. Their concepts involve more than relations between what actually exists. |