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. |
| 16466 | Strong necessity is always true; weak necessity is cannot be false [Stalnaker] |
| Full Idea: Prior had a strong and a weak reading of necessity, where strong necessity is truth in all possible worlds, while weak necessity is falsity in no possible world. | |
| From: Robert C. Stalnaker (Mere Possibilities [2012], 4.3) | |
| A reaction: [K.Fine 2005:Ch.9 is also cited] The point of the weak one is that in some worlds there might not exist the proposition which is the candidate for truth or falsehood. |
| 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!] |