Hurley 12th ed. Deduction and Induction, PP. 33-39 (Textbook) (7 pp.) DIRECTIONS: Are the following deductive or inductive arguments? Why? Indicate exactly how you came to your decision. That is, (i) are there indicator words that provide evidence, and/or (ii) do you believe that the nature of the inferential link between premises and conclusion provides evidence, and/or (iii) does the character or form of argument provide evidence? Don't simply copy and paste (i)-(iii), you also need to explain what they mean in relation to each argument. ------------------------------------------------------- EXAMPLE full-point answer: P1: The meerkat is closely related to the suricat. P2: The suricat thrives on beetle larvae. C: Therefore, probably the meerkat thrives on beetle larvae. The above argument is inductive. (i) The inductive indicator word probably is used. This means that the arguer is acknowledging that it is possible that their conclusion that meerkat probably thrives (i.e. grow or develop well or vigorously.) on beetle larvae is false. Yet, despite this possibility, they believe that their conclusion is probably true. (ii) The nature of the inferential link between the premises and the conclusion provides evidence that this argument is inductive. Because, even if the premises are true, I can still imagine the conclusion turning out to be false. For example, it is entirely within the realm of possibility that there could be some reason that -- even though meerkats are biologically very similar to suricats -- beetle larvae is not nutritious for meerkats like it is for suricats. So, this means that the argument is inductive, not deductive. (iii) The character of the argument provides evidence that it is inductive. Because it is an argument from analogy, which is an inductive argument kind. ------------------------------------------------------------ P1: The meerkat is a member of the mongoose family. P2: All members of the mongoose family are carnivores. C: Therefore, it necessarily follows that the meerkat is a carnivore. P1: Triangle A is congruent with triangle B. P2: Triangle A is isosceles. C: It follows that triangle B is isosceles. P1: Both front and rear doors were found open after the burglary. P2: There were pry marks around the lock on the rear door found after the burglary. P3: Near the threshold of the rear door there were deposits of mud found after the burglary . C: It must be the case that the thief entered through the rear door and left through the front. Hurley 12th ed. Validity, Truth, Soundness, Strength, Cogency [Textbook] 44-52 (10 pp.) DIRECTIONS: The following arguments are deductive. (a) Indicate whether each is valid or invalid. (b) Indicate whether the argument is sound or unsound. Finally, (c) indicate whether the premises and conclusion are actually true or actually false. How do you know? (d) Indicate whether this is an argument that makes sense (i.e. is valid) even though the premises and/or the conclusion are actually false. Explain? -------------------------------------------------- EXAMPLE full-point answer: P1: Moby Dick was written by Shakespeare. P2: Moby Dick is a science-fiction novel. C: It follows that Shakespeare wrote a science-fiction novel. (a) The above argument is valid. (b) The above argument is unsound. (c) P1 is actually false. Because Herman Melville wrote Moby Dick. P2 is actually false. Because it is fiction, but not science-fiction. Because it is generally about whale hunting. "Science-fiction" is instead fiction based on imagined future scientific or technological advances and major social or environmental changes. The conclusion is actually false. Because Shakespeare was not a science-fiction writer. (d) This argument makes sense, even though the premises and the conclusion are actually false. Because if we imagine that the premises are true, then they support the conclusion. -------------------------------------------------- P1: London is north of Paris. P2: London is south of Edinburgh. C: It follows that Paris is south of Edinburgh. P1: If George Washington was beheaded, then George Washington died. P2: George Washington died. C: Therefore, George Washington was beheaded. P1: The longest river in South America is the Amazon. P2: The Amazon flows through Brazil. C: Therefore, the longest river in South America flows through Brazil. P1: If President Barack Obama was born in Massachusetts, then he is a native of New England. P2: Barack Obama is not a native of New England. C: Therefore, Barack Obama was not born in Massachusetts. P1: Some fruits are green. P2: Some fruits are apples. C: It follows that some fruits are green apples. P1: All physicians are individuals who have earned degrees in political science. P2: Some lawyers are physicians. C: Therefore, some lawyers are persons who have earned degrees in political science. P: The United States Congress has more members than there are days in the year. C: Therefore, at least two members of Congress have the same birthday. DIRECTIONS: The following arguments are inductive. (a) Indicate whether each is strong or weak. (b) Indicate whether the argument is cogent or uncogent. Finally, (c) indicate whether the premises and conclusion are actually true or actually false. (d) Indicate whether this is an argument that makes sense (i.e. is strong) even though the premises and/or the conclusion are actually false. Explain? P: The grave marker at Arlington National Cemetery says that John F. Kennedy is buried there. C: It must be the case that Kennedy really is buried in that cemetery. P1: The ebb and flow of the tides has been occurring every day for millions of years. P2: But nothing lasts forever. C: Therefore, probably the motion of the tides will die out within a few years. P: The vast majority of Rose Bowl games (in Pasadena, California) have been played in freezing-cold weather. C: Therefore, probably the next Rose Bowl game will be played in freezing-cold weather. P: Franklin Delano Roosevelt said that we have nothing to fear but fear itself. C: Therefore, women have no reason to fear serial rapists. P1: Most popular film stars are millionaires. P2: Viola Davis is a popular film star. C: Therefore, probably Viola Davis is a millionaire. P: Constructing the great pyramid at Giza required lifting massive stone blocks to great heights. C: Probably the ancient Egyptians had some antigravity device to accomplish this feat. P1: Paleontologists have unearthed the fossilized bones of huge reptiles, which we have named dinosaurs. P2: Tests indicate that these bones are more than 50 million years old. C: Therefore, probably dinosaurs really did roam the earth 50 million years ago. P: The Declaration of Independence says that all men are endowed by their creator with certain unalienable rights. C: Therefore it probably follows that a creator exists.