An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

IMMEDIATE INEERENCE. 95
tions, the relation between S and P represented by the
following diagram.
Fig. 8.
(5) Show how to get the Converse of the Contrary of the
Contradictory of the "
proposition Some crystals are cubes."
How is it related to the original ? proposition [L.]
(6) All crystals are solids.
Some solids are not crystals.
Some not-crystals are not solids.
No crystals are not solids.
Some solids are crystals.
Some not-solids are not crystals.
All solids are crystals.
Assign the logical relation, if any, between each of these
propositions and the first of them. [L.]
(7) How must a Singular Proposition be logically con
tradicted? (Cf. ch. II. 13 adfinem)
(8) Take the "All proposition sciences are useful," and
determine precisely what it affirms, what it denies, and
what it leaves doubtful, concerning the relations of the terms
"
"
science
and
"
useful thing." [L.]
(9) Give the obverted converse of
(a) Every truthful man is trusted.
No (/;) cultivated district is uninhabited.
(c) Some British subjects are dishonest. 1
Give the obverted contrapositive of
(d) Every poison is capable of destroying life.
(c) No idle person is deserving of success.
Some (_/") unjust laws are not repealed.
1 The term "alien" may be taken as the logical contradictory of
"
British subject."