display all the ideas for this combination of philosophers
6 ideas
| 12381 | What is necessary cannot be otherwise [Aristotle] |
| Full Idea: What is necessary cannot be otherwise. | |
| From: Aristotle (Posterior Analytics [c.327 BCE], 88b32) | |
| A reaction: If the next interesting question is the source of necessity, then the question seems to be 'what prevents it from being otherwise?'. |
| 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. |
| 1690 | A stone travels upwards by a forced necessity, and downwards by natural necessity [Aristotle] |
| Full Idea: There are two types of necessity, one according to nature and impulse, the other by force and contrary to impulse. A stone travels upwards and downwards from different necessities. | |
| From: Aristotle (Posterior Analytics [c.327 BCE], 94b38) |
| 14641 | A deduction is necessary if the major (but not the minor) premise is also necessary [Aristotle] |
| Full Idea: It sometimes results that the deduction becomes necessary when only one of the premises is necessary (not whatever premise it might be, however, but only the premise in relation to the major extreme [premise]). | |
| From: Aristotle (Prior Analytics [c.328 BCE], 30a15) | |
| A reaction: The qualification is brackets is said by Plantinga (1969) to be a recognition of the de re/ de dicto distinction (later taken up by Aquinas). Plantinga gives two examples to illustrate his reading. |
| 12259 | Reasoning is when some results follow necessarily from certain claims [Aristotle] |
| Full Idea: Reasoning [sullogismos] is a discussion in which, certain things having been laid down, something other than these things necessarily results through them. | |
| From: Aristotle (Topics [c.331 BCE], 100a25) | |
| A reaction: This is cited as the standard statement of the nature of logical necessity. One might challenge either the very word 'necessary', or the exact sense of the word employed here. Is it, in fact, metaphysical, or merely analytic? |
| 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!] |