Necessity and sufficiency - Wikipedia
网页In logic and mathematics, necessity and sufficiency are terms used to describe a conditional or implicational relationship between two statements. For example, in the conditional statement: "If P then Q ", Q is necessary for P, because the truth of Q is guaranteed by the truth of P. (Equivalently, it is impossible to have P without Q, or the ...
Necessary and Sufficient Conditions - Stanford Encyclopedia of Philosophy
网页2003年8月15日 · In a well-known attempt to use the terminology of necessary and sufficient conditions to illuminate what it is for one thing to be cause of another thing, J. L. Mackie proposes that causes are at a minimum INUS conditions, that is, “Insufficient but Necessary parts of a condition which is itself Unnecessary but Sufficient” for their effects ...
充分必要条件 - 维基百科，自由的百科全书
网页充分必要條件，簡稱 充要條件，是 逻辑学 中用于描述两个陈述之间的条件关系或包含关系的术语。 在 逻辑学 中： 当命题「若P則Q」为真时，P称为Q的 充分条件，Q称为P的 必要条件。 因此： 当命题「若P則Q」與「若Q則P」皆为真时，P是Q的 充分必要条件，同时，Q也是P的 充分必要条件。 当命题「若P則Q」为真，而「若Q則P」为假时，我们称P是Q的 充分不必要条件，Q是P的 必要不充分条件，反之亦然。 必要條件. P是Q的必要條件，代表「 …
The Concept of Necessary Conditions and Sufficient Conditions
网页Definition: A condition A is said to be necessary for a condition B, if (and only if) the falsity (/nonexistence /non-occurrence) [as the case may be] of A guarantees (or brings about) the falsity (/nonexistence /non-occurrence) of B.
充分条件与必要条件 - 知乎 - 知乎专栏
网页一个具备 批评性思维 的人，一定能区分充分条件与必要条件（Sufficient and Necessary ）。. 一、必要条件（Necessary）. P是Q的必要条件，Q不为真；除非P为真的。. 仅当P为真时，Q（可以）为真。. 也就是说： 当P为Q的必要条件时，P是Q的必需品，想要Q为 …
2.3: Necessary and Sufficient Conditions - Humanities LibreTexts
网页Necessary and Sufficient conditions are things that are both enough for and required for something else. If X is a necessary and sufficient condition for Y, then: If X obtains, then Y must obtain (so any time X obtains, Y also obtains)
What is the difference between necessary and sufficient conditions?
网页A sufficient condition is stronger than a necessary condition. If you tell me that you have a red or blue element I can't say for sure if it is in the purple set, but if you tell me that you have a purple element I now for sure that it is in the red and blue sets.
[M06] Necessity and sufficiency - University of Hong Kong
网页§2. Sufficient conditions. To say that X is a sufficient condition for Y is to say that the presence of X guarantees the presence of Y. In other words, it is impossible to have X without Y. If X is present, then Y must also be present. Again, some examples : Being a square is sufficient for having four sides.
Necessary and Sufficient Conditions - Stanford Encyclopedia of Philosophy
网页2003年8月15日 · The account of necessary and sufficient conditions just outlined is particularly apposite in dealing with logical, conceptual and definitional conditions. The hook operator ("⊃") captures much of what is meant by reference to necessary and sufficient conditions in such contexts.
Necessary and Sufficient Conditions – Introduction to …
网页5 Necessary and Sufficient Conditions. Michael Shaffer. The concepts of necessary and sufficient conditions play central and vital roles in analytic philosophy. For example, being an unmarried male is a necessary condition for being a bachelor and being a bachelor is a sufficient condition for being an unmarried male.
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