(5) All discontented men are unhappy.
.'. No contented men are unhappy.
(6) Books being a source of instruction, our knowledge must come
from our libraries.
(7) All Jews are Semitic.
.'. Some non-Semitic people are not Jews.
5. Show by what kind of inference each of the subjoined propositions follows from
All discontented men are unhappy.
(1) All happy men are contented.
(2) Some discontented men are unhappy.
(3) Some contented men are happy.
(4) Some unhappy men are not contented.
(5) No discontented men are happy.