Kitap 7
1.73
Opposite in character to the foregoing is a proposition which declares what is less the fact, as e.g. It is less or not so much night as day. Further, among propositions there are some which in respect of truth and falsehood stand opposed to one another, of which the one is the negative of the other, as e.g. the propositions It is day and It is not day. A hypothetical proposition is therefore true, if the contradictory of its conclusion is incompatible with its premiss, e.g. If it is day, it is light. This is true. For the statement It is not light, contradicting the conclusion, is incompatible with the premiss It is day. On the other hand, a hypothetical proposition is false, if the contradictory of its conclusion does not conflict with the premiss, e.g. If it is day, Dion is walking. For the statement Dion is not walking does not conflict with the premiss It is day.
1.74
An inferential proposition is true if starting from a true premiss it also has a consequent conclusion, as e.g. Since it is day, the sun is above the horizon. But it is false if it starts from a false premiss or has an inconsequent conclusion, as e.g. Since it is night, Dion is walking, if this be said in day-time. A causal proposition is true if its conclusion really follows from a premiss itself true, though the premiss does not follow conversely from the conclusion, as e.g. Because it is day, it is light, where from the it is day the it is light duly follows, though from the statement it is light it would not follow that it is day. But a causal proposition is false if it either starts from a false premiss or has an inconsequent conclusion or has a premiss that does not correspond with the conclusion, as e.g. Because it is night, Dion is walking.
1.75
A probable judgement is one which induces to assent, e.g. Whoever gave birth to anything, is that thing’s mother. This, however, is not necessarily true; for the hen is not mother of an egg.
