Slide 1Remember…Valid Deductive ArgumentsSlide 4Slide 5Invalid Deductive ArgumentValid does not mean “true.”Sound vs. UnsoundValid but UnsoundSlide 10Strong Inductive ArgumentsWeak Inductive ArgumentsSlide 13Slide 14Cogent vs. Uncogent Inductive ArgumentsIn ConclusionReview for QuizReview!Slide 19We looked at five common patterns of deductive reasoningWe studied six common patterns of inductive reasoningDeductive arguments are either valid or invalidSound vs. UnsoundInductive arguments are either strong or weakCogent vs. uncogentRecap of Key DefinitionsRecap of Key Definitions…Recap of Key Definitions…Recap of Key Definitions…Recap of Key Definitions…For Next TimeCritical ReasoningWeek 4: Class 2Remember…Valid Deductive ArgumentsIt is impossible for all the premises to be true and the conclusion false. If the premises are true, the conclusion must be true. The conclusion follows necessarily from the premises.It is not necessary to know whether an argument’s premises or conclusion are true to know whether the argument is valid. Some valid arguments have obviously false premises and a false conclusion.Some valid arguments have false premises and a true conclusion.And some valid arguments have true premises and a true conclusion.Invalid Deductive Argument…a deductive argument in which the conclusion does not follow necessarily from the premises.Valid does not mean “true.” Valid means that the argument is well reasoned, that the pattern of reasoning is a logically reliable pattern of reasoning, that the conclusion follows necessarily from the premises. If the argument’s premises were true, would the conclusion also have to be true? If the answer is yes, the argument is valid. If the answer is no, the argument is invalid.Sound vs. UnsoundSound deductive arguments are both valid and have all true premises.All human beings will die. Clark is a human being. Clark will die.All Scottish Folds are cats. Some pets are Scottish Folds. Therefore, some pets are cats. Unsound deductive arguments are either invalid or have at least one false premise.Valid but UnsoundAll women are mortal. Cats are women. Therefore, cats are mortal. Note that the first premise and the conclusion are true. All Drexel professors have three eyes. Patricia is a Drexel professor. Therefore, Patricia has three eyes.Invalid Deductive ArgumentsBONUS: Analyze the arguments in the video and send your thoughts to Patricia by Friday at 10am.Strong Inductive ArgumentsIf the premises are true, the conclusion is probably true.The last ten times I’ve played poker, I’ve won money. I’m playing poker tonight. I’ll probably win money tonightWeak Inductive ArgumentsThe conclusion does not follow probably from the premises. The last ten times I’ve played poker, I’ve won money. I’m playing poker tonight. I probably won’t win money tonight.Like deductively valid arguments, inductively strong arguments can have various combinations of truth or falsity in the premises and conclusion. Some strong arguments have false premises and a probably false conclusion.All swans we have seen so far have been white. (false: I’ve seen a black one) Therefore, it is likely that all swans are white. (False)No strong inductive argument can have true premises and a probably false conclusion.If the argument’s premises were true, would the conclusion probably be true? If the answer is yes, the argument is strong. If the answer is no, the argument is weak.Cogent vs. Uncogent Inductive ArgumentsIf an argument both is inductively strong and has all true premises, it is said to be a cogent argument. If an inductive argument either is weak or has at least one false premise, it is an uncogent argument.In ConclusionReview for Quiz42 Multiple Choice Questions!You have 1 hour to complete it!You must complete the quiz once you start!!!YOU CAN ONLY ACCESS IT ONCE!!!!!!!!!!!!!!!You may access the quiz from 7:30AM Thursday to 7:30PM THIS SUNDAYHint: You really should review the problems in the book…Review!All arguments are either deductive or inductive.In a deductive argument, the conclusion is claimed to follow necessarily from the premises. In an inductive argument, the conclusion is claimed to follow only probably from the premises.In deciding whether an argument is deductive or inductive, one should apply four simple tests. The indicator word test asks, Are there any indicator words—words such as probably, necessarily, and likely—that signal whether the argument is intended to be deductive or inductive? The strict necessity test asks, Does the conclusion follow with strict necessity from the premises? The common pattern test asks, Does the argument have a pattern that is characteristically deductive or inductive? The principle of charity test urges us to treat doubtful arguments in whatever way is most favorable to the arguer.We looked at five common patterns of deductive reasoningA hypothetical syllogism is a three-line argument that contains at least one conditional (if-then) statement. A categorical syllogism is a three-line deductive argument in which each line in the argument begins with all, some, or no. An argument by elimination seeks to logically rule out various possibilities until only a single possibility remains. In an argument based on mathematics, the conclusion is claimed to depend largely or entirely on some mathematical calculation or measurement (perhaps in conjunction with one or more nonmathematical premises).In an argument from definition, the conclusion is presented as being true by definition.We studied six common patterns of inductive reasoningAn inductive generalization is an argument in which a generalization is claimed to be likely on the basis of information about some members of a particular class. In a predictive argument, a prediction is defended with reasons.An argument from authority asserts that a claim is true and then supports that claim by alleging that some presumed authority or witness has said that the claim is true. A causal argument asserts or denies that something is the cause of something else. A statistical argument rests on statistical evidence—that is, evidence that some percentage of some group has some particular characteristic. In an argument from analogy, the conclusion is claimed to depend on an analogy