(c) No wingless birds are songsters.
(d) Some winged birds are not songsters.
What can you infer from (a) and (b) jointly, and what from (c) and (d) jointly? [S]
14. "The author actually supposes that, because Professor Fawcett denies that all wealth is money, he denies that all money is wealth." Analyse the differences of opinion implied in the above passage. [S]
15. Take any universal affirmative proposition; convert it by obversion (contraposition); attach the negative particle to the predicate, and again convert. Interpret the result exactly, and say whether it is or is not equivalent to the original proposition. [S]
16. What information about the term "solid body" can we derive from the proposition, "No bodies which are not solids are crystals"? [S]
17. Discuss the proposal to treat all propositions as affirmative.
18. Convert the proposition "A is probably B." What information does the proposition give us concerning B? [S]
19. Show in how many ways you can deny the following assertions: All cathedral towns are all cities; Canterbury is the Metropolitan see. [S]