Editorial note — Chapter VI

397 The following is a simple, not a complex, constructive dilemma:

If A is B, E is F or G is H ; and if C is D, E is F or G is H ; but Either A is B or C is D ; therefore, Either E is F or G is H.

The hypotheticals which here constitute the major premiss have a common consequent; but since this is itself alternative, the conclusion appears in the alternative form. This case is analogous to the following,—All M is P or Q, All S is M, therefore, All S is P or Q,—where the conclusion of an intrinsically categorical syllogism also appears in the alternative form. Compare the note on page 359.