Translate the premises and conclusion into the symbols of propositional logic. Construct a truth table in which you analyze the argument for validity. You can construct a truth a table by inserting a table into a Microsoft Word document (from the INSERT option in Word, choose “table.” You will then have an opportunity to choose how many rows and columns you would like your table to be.) Is your argument valid or invalid? If valid, say why it is valid; identify the rows in the truth table that make the argument valid. If the argument is invalid, identify a counterexample; point to a row in your truth table that makes the argument invalid.
- Humans evolved from lower life forms given that either human life evolved from inanimate matter apart from divine causes or God created human life via evolution. God created life via of evolution. It follows that humans evolved from lower life forms. (H: Human life evolved from lower life forms; M: Human life evolved from inanimate matter apart from divine causes; G: God created human life via evolution)
- Augustine achieves heaven if Augustine is virtuous. But Augustine is happy provided that he is not virtuous. Augustine does not achieve heaven only if he is not happy. Therefore, Augustine achieves heaven. (A: Augustine achieves heaven; V: Augustine is virtuous; H: Augustine is happy)
- It is morally permissible for extraterrestrials to eat humans on the condition that it is morally permissible for humans to eat animals. But either it is not morally permissible for extraterrestrials to eat humans or human life lacks intrinsic value. Human life has intrinsic value. Therefore it is not morally permissible for humans to eat animals. (E: It is morally permissible for extraterrestrials to eat humans; H: It is morally permissible for humans to eat animals; V: Human life has intrinsic value)
- American foreign policy is bankrupt unless it is based on clear moral principles. American foreign policy is not based on clear moral principles just in case it is based primarily on the national interest. Unfortunately American foreign policy is based primarily on the national interest. Therefore, American foreign policy is bankrupt. (B: American foreign policy is bankrupt; M: American foreign policy is based on clear moral principles; N: American foreign policy is based primarily on national interest.)
- On the condition that landmines are designed to inflict horrible suffering, they ought to be banned unless inflicting horrible suffering is sometimes justified. It is not true that inflicting horrible suffering is sometimes justified, but it is true that landmines are designed to inflict horrible suffering. Therefore, landmines ought to be banned. (L: Landmines are designed to inflict horrible suffering; B: Landmines ought to be banned; S: Inflicting horrible suffering is sometimes justified)
