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|Logical Form||I 139 ~
Requirement / logical form / Logic / Entailment / Chisholm: if certain features of a situation "require" that a certain reaction takes place, then this requirement can be neutralized by other features of this situation. So it may be that p requires that q, and p and r do not require that q - although p-and-q includes (entails) that p.
Objects of thought Oxford 1971
Arthur N. Prior
Papers on Time and Tense 2nd Edition Oxford 2003