139
(9) 1. ( x)(Ax ~Bx) p
EXERCISE 13-1:
(1) 3. Fx Gx 2EI
(3) 5. Hc 3Simp
140
(5) 3. ~ ~ Pa AP/ ~ Pa
(7) 3. ~ (~ Px ~Ex) 2 EI
(9) 4. Gb Fb 1UI
EXERCISE 13-2:
1. Fg (x) [Fx (x=g)]
141
EXERCISE 13-3:
1. (x) {Sx (y) {[Sy (x y)] Ixy}} (Sx =“x is a student”; Ixy =“x is more
11. Dms (x) [Dxs (x=m)] (m= “Mary”; s= “Sonia”; Dxy = “xis a daughter of
EXERCISE 13-4:
A.1. Nonsymmetrical, nontransitive, nonreflexive
142
B. 1. (x) (y) (Fxy ~Fyx) p/ (x) ~ Fxx
EXERCISE 13-5:
1. Some say that the levels-of-language theory solves this paradox. For it forbids a
EXERCISE 13-6:
1. Those that require an identity clause (using obvious abbreviations):
Those that don’t require an identity clause:
question. Further, in that case, the sentence “Food fdoes not have the power
143
144
EXERCISE 14-1:
1. All rich people are sinners.
11. Some omnivores are vegetarian.
EXERCISE 14-2:
(1) 1. “No wars are hellish” is false (because “All wars are hellish” and “No wars are
EXERCISE 14-3:
EXERCISE 14-4:
(5) There are many sentences that can be inferred. The answers given will just be
sentences that can be immediately inferred from truth of the given sentence.
145
EXERCISE 14-5:
EXERCISE 14-6:
146
EXERCISE 14-7:
3. Invalid
5. Valid
EXERCISE 14-8:
(1) 1. All sinners are punished in the next life.
O
C
147
(3) 1. Some who are permitted to vote are not people who vote.
(5) 1. All who deserve the fair are rich.
(7) 1. No classes about good reasoning are boring.
148
(9) 1. Some acts of telling the truth are not acts that are most likely to sell products.
(11) 1. All people who live by violence are people who die by violence.
(13) 1. All vain people are people who regularly look at themselves in mirrors.
149
(15) 1. No wet-whistled drunks are people who are ignored.
EXERCISE 14-9:
(1) 1. No honest men are crooks.
(5) 1. All books that conceal our theft of the American continent from the Indians are
(7) 1. All people whose primary interest is prestige or an easy life are pretty poor
(9) 1. No policies based on the judgment of some of America’s best-known political
150
EXERCISE 14-10:
(1) 1. All fickle people are disliked.
(3) 1. All barbers are extroverts.
151
(5) 1. All people who can be admitted
1. No people in graduate school
EXERCISE 14 11:
1. We would lose the ability to deal with claims of ordinary language that do not
have existential import. An example would be the claim “All people caught