Of the Partly Conjunctive Syllogism regarded as an Immediate Inference.
§ 753. It is the assertion of fact in the minor premiss, where we have the application of an abstract principle to a concrete instance, which alone entitles the partly conjunctive syllogism to be regarded as a syllogism at all. Apart from this the forms of semi-conjunctive reasoning run at once into the moulds of immediate inference.
§ 754. The constructive mood will then be read in this way—
If A is B, C is D,
.'. A being B, C is D.
reducing itself to an instance of immediate inference by subaltern opposition—
Every case of A being B, is a case of C being D.
.'. Some particular case of A being B is a case of C being D.
§ 755. Again, the destructive conjunctive will read as follows—
If A is B, C is D,
.'. C not being D, A is not B.
which is equivalent to
All cases of A being B are cases of C being D.
.'. Whatever is not a case of C being D is not a case of A being B.
.'. Some particular case of C not being D is not a case of A being
B.