Books on Amazon
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._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution.
Objects of thought Oxford 1971
Arthur N. Prior
Papers on Time and Tense 2nd Edition Oxford 2003