Critical Thinking and Composition E. F. Haven This work edited by E. F. Haven is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License (available online at http://creativecommons.org/licenses/by- sa/4.0/). This work, “Critical Thinking and Composition” is a derivative of “Logic and Critical Thinking” by Matthew J Van Cleave, used under CC BY 2.0 (https://creativecommons.org/licenses/by/ 2.0/) Version 0.6 (June, 2018) Table of Contents Chapter 1: Arguments.....................................................................................................................3 1.1 What is an argument?........................................................................................................3 Exercise 1:..........................................................................................................................................6 1.2 Identifying arguments.......................................................................................................7 Exercise 2:........................................................................................................................................11 1.3 Arguments vs. Explanations.......................................................................................12 Exercise 3:.......................................................................................................................................14 1.4 Using your own paraphrases of premises and conclusions to reconstruct arguments in standard form.................................................................16 Exercise 4: See Handout on Canvas............................................................................19 1.5 Cleaning Up Language.................................................................................................19 Exercise 5: See Handout on Canvas............................................................................24 1.6 Arguments with missing premises.......................................................................24 Exercise 6:.......................................................................................................................................31 1.7 More complex argument structures....................................................................32 Exercise 7:.......................................................................................................................................37 1.8 Analyzing a real-life argument................................................................................39 Chapter 2: Inductive Arguments..........................................................................................55 2.1 Evaluating Inductive Arguments............................................................................55 2.2 Generalizations...................................................................................................................56 Exercise 8:......................................................................................................................................63 2.3 Analogies................................................................................................................................65 Exercise 9:......................................................................................................................................69 2.4 Causal Arguments.............................................................................................................71 Exercise 10:....................................................................................................................................82 Chapter 3: Deductive Arguments........................................................................................84 3.1 Validity.......................................................................................................................................84 Exercise 11:.....................................................................................................................................89 3.2 Propositional logic and the four basic truth functional connectives ...............................................................................................................................................................90 Exercise 12:....................................................................................................................................97 3.3 Negation and disjunction...........................................................................................98 Exercise 13:..................................................................................................................................105 3.4 Using parentheses to translate complex sentences...........................106 1 Exercise 14:...................................................................................................................................114 3.5 Conditionals........................................................................................................................115 Exercise 15:..................................................................................................................................120 3.6 “Unless”..................................................................................................................................122 3.7 Proofs and the 8 valid forms of inference.....................................................123 Exercise 16:..................................................................................................................................134 3.8 How to construct proofs............................................................................................137 Exercise 17:..................................................................................................................................144 Chapter 4: Erroneous Logic...................................................................................................148 4.1 Composition fallacy......................................................................................................148 4.2 Division fallacy...................................................................................................................151 4.3 Begging the question..................................................................................................152 4.4 False dichotomy..............................................................................................................155 4.5 Equivocation.......................................................................................................................157 4.6 Slippery slope fallacies.............................................................................................158 4.7 Ad Hominem......................................................................................................................165 4.8 Straw man...........................................................................................................................168 4.9 Tu quoque............................................................................................................................170 4.10 Genetic fallacy................................................................................................................171 4.11 Appeal to consequences........................................................................................173 4.12 Appeal to authority......................................................................................................174 4.13 Formal Fallacies.............................................................................................................175 2 Chapter 1: Arguments 1.1 What is an argument? This is an introductory textbook in logic and critical thinking. Both logic and critical thinking involve the analysis and assessment of arguments. “Argument” is a word that has multiple distinct meanings, so it is important to be clear from the start about the sense of the word that is relevant to the study of logic. In one sense of the word, an argument is a heated exchange of differing views as in the following: Sally: Abortion is morally wrong and those who think otherwise are seeking to justify murder! Bob: Abortion is not morally wrong and those who think so are right-wing bigots who are seeking to impose their narrow- minded views on all the rest of us! 3 Chapter 1: Arguments Sally and Bob are having an argument in this exchange. That is, they are each expressing conficting views in a heated manner. However, that is not the sense of “argument” with which logic is concerned. Logic concerns a different sense of the word “argument.” An argument, in this sense, is a reason for thinking that a statement, claim or idea is true. For example: Sally: Abortion is morally wrong because it is wrong to take the life of an innocent human being and a fetus is an innocent human being. In this example Sally has given an argument against the moral permissibility of abortion. That is, she has given us a reason for thinking that abortion is morally wrong. The conclusion of the argument is the frst four words, “abortion is morally wrong.” But whereas in the frst example Sally was simply asserting that abortion is wrong (and then trying to put down those who support it), in this example she is offering a reason for why abortion is wrong. We can (and should) be more precise about our defnition of an argument. But before we can do that, we need to introduce some