ABSTRACT
“There is such a thing as this sense-datum” expresses a fact.
The fact which it expresses is one of which the contradictory is self-contradictory & yet the fact in question is not a necessary fact.
It is not necessary, because “There might have been no such thing as this sense-datum” also expresses a fact. 〈I’m not quite sure of this.〉
“There might have been …” is not equivalent to ““There is no such thing as this sense-datum” might have been true”: “There is no such thing as this sense-datum” couldn’t have been true, because it is self-contradictory. What it is equivalent to is: “There might have been no such prop. as “There is such a thing as this sense-datum” nor yet as “There is no such thing as this sense-datum””. 〈Call this: p subsists contingently.〉
It’s not the case, therefore, that wherever ~ p entails a contradiction, p is a necessary truth: it’s only the case that where both ~ p entails a contradiction & p subsists necessarily, then p is necessary.
Hence there are 2 different kinds of contingent truth.
It’s therefore also not the case that p entails q only where p ⊃ q is a necessary truth. For, p ⊃ q can be a necessary truth only where “There might have been no such prop. as p ⊃ q” is false; and there might have been no such prop. as p ⊃ q wherever there might have been no such prop. as p or as q; & there certainly might have been no such prop. as “This sense-datum is round & white”, & therefore none such as “This sense-datum is round & white” ⊃ “This sense-datum is white”.
