Lecture 17

Class Exercises

Exercise 1:[1]

Use Venn diagrams to determine whether the following categorical syllogisms are valid or invalid.

  1. (P1) All corporations that overcharge their consumers are unethical businesses.

(P2) Some unethical businesses are investor-owned utilities.

THEREFORE,

(C)Some investor-owned utilities are corporations that overcharge their customers.

  1. (P1) No individuals truly concerned with the plight of suffering humanity are people motivated primarily by self-interest.

(P2) All television evangelists are people motivated primarily by self-interest.

THEREFORE,

(C) Some television evangelists are not individuals truly concerned with the plight of suffering humanity.

  1. (P1) Noome television evangelists are not individuals truly concerned with the plight of suffering humanity.
    self-interest.11111111111 engineering majors are candidates for nightly hookups.

(P2) No candidates for nightly hookups are deeply emotional individuals.

THEREFORE,

(C) No deeply emotional individuals are engineering majors.

  1. (P1) No pediatricians are individuals who jeopardize the health of children.

(P2) All faith healers are individuals who jeopardize the health of children.

THEREFORE,

(C) No faith healers are pediatricians.

  1. (P1) Some ATM locations are places criminals lurk.

(P2) All places criminals lurk are places to avoid at night.

THEREFORE,

(C) Some places to avoid at night are ATM locations.

  1. (P1) All circular triangles are plane figures.

(P2) All circular triangles are three-sided figures.

THEREFORE,

(C) Some three-sided figures are plane figures.

  1. (P1) No people who profit from the illegality of their activities are people who want their activities legalized.

(P2) All drug dealers are people who want their activities legalized.

THEREFORE,

(C) No drug dealers are people who want their activities legalized.

  1. (P1) Some communications satellites are rocket-launched failures.

(P2) All communication satellites are devices with antennas.

THEREFORE,

(C) Some devices with antennas are rocket-launched failures.

  1. (P1) All survivalists are people who enjoy simulating war games.

(P2) No people who enjoy simulated war games are soldiers who have tasted the agony of real war.

THEREFORE,

(C) All soldiers who have tasted the agony of real war are survivalists.

  1. (P1) No theocracies are regimes open to change.

(P2) All theocracies are governments that rule by force.

THEREFORE,

(C) Some governments that rule by force are not regimes open to change.

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[1] Exercises taken from Patrick Hurley. A Concise Introduction to Logic, 11th edition, Belmont: Wadsworth, Cengage Learning, (2012), 277-278