display all the ideas for this combination of texts
3 ideas
| 12611 | Necessity makes alternatives impossible [Aristotle] |
| Full Idea: Necessity is what makes it impossible for something to be other than it is. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1015b03) | |
| A reaction: Note that necessity here seems like an active force, rather than a mere description of a logical or metaphysical state of affairs. The underlying idea seems to be that essences enforce necessities, but it doesn't say that here. |
| 17852 | A thing has a feature necessarily if its denial brings a contradiction [Aristotle] |
| Full Idea: If anything has the property of being perishable it has it of necessity, on pain of one and the same thing being perishable and imperishable. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1059a05) | |
| A reaction: Of course the perishable could become imperishable over time, without contradiction. This illustrates the foundational idea that a proposition is necessary if its negation is a contradiction. [...actually this argument is invalid as it stands!] |
| 13820 | The idea that anything which can be proved is necessary has a problem with empty names [Bostock] |
| Full Idea: The common Rule of Necessitation says that what can be proved is necessary, but this is incorrect if we do not permit empty names. The most straightforward answer is to modify elementary logic so that only necessary truths can be proved. | |
| From: David Bostock (Intermediate Logic [1997], 8.4) |