(6) Some happy men are contented.
(7) Some contented men are not unhappy.
(8) Some unhappy men are discontented.
(9) No happy men are discontented.
(10) Some discontented men are not happy.
(11) Some happy men are not discontented.
(12) None but unhappy men are discontented.
From how many of these propositions can the original one be derived?
And why not from all?
CHAPTER VII.
What kind of inference have we here?—