Matthews Key for Informal Logic Exercises 1. Use these answers to grade and correct your homework assignment. A perfect score would be 100.

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1 Matthews Key for Informal Logic Exercises 1 Use these answers to grade and correct your homework assignment. A perfect score would be 100. Please submit your exercises, marked up with totals for each section, as well as your total score on the first page by your name. Syllogisms: each syllogism is worth 5 points for a total of 20 points. Judging Arguments Exercises for Step 1: ranslation: EACH SYLLOGISM IS WORH 5 POINS FOR A OAL OF 15 POINS: IMPLICI PREMISES HA FUNCION EXACLY LIKE PRESUPPOSIIONS DO IN OUR UNEXAMINED SYSEM OF BELIEFS. 1) P1 No one who wants fame can be trusted. P2 Peter is a journalist. P3 [Journalists want fame] (IMPLICI) C Peter cannot be trusted. 2) P1 [If something never existed, then it can t be restored]. (IMPLICI) P2 Democracy in Haiti never existed. ˆ Democracy in Haiti can t be restored. 3) P1 [Either the fetus becomes human at the moment of conception, or it becomes human at some moment thereafter.] (IMPLICI) P2 here is a continuity of development from conception on. P3 If P2, then no stage is radically different. P4 If no stage is radically different, then there is no stage after conception at which the fetus becomes human. ˆ he fetus becomes human at the moment of conception. Exercises for Step 2: Evaluation: EACH NUMBERED EXERCISE IS WORH 2 POINS FOR A OAL OF 40 POINS : Indicate if the following arguments are valid or invalid, and whether the premises

2 Matthews Key for Informal Logic Exercises 2 and conclusions are true or false. VALID/INVALID 1) Everyone who studies logic is Beautiful RUE/FALSE? ALL UP O YOUR OWN? OBSERVAION

3 Matthews Key for Informal Logic Exercises 3 Matthews Philosophical Framework I am beautiful.? INVALID => AC 2) I am studying logic. Every Supreme Court Justice is a U.S. Citizen I am not a Supreme Court? INVALID => DA 3) Justice. I am not a U.S. Citizen. If I put my hand in a flame, then I will be burned. INVALID => DA I will not put my hand in a 4) flame. I will not be burned. If I have unprotected sex, then F I will be safe from disease. F I will not have unprotected F INVALID=> DA 5) sex. I will not be safe from disease. All Virginians are New F Yorkers. VALID CHAIN ARGUMEN All New Yorkers are U.S. 6) Citizens. All Virginians are U.S. Citizens All snakes are reptiles All reptiles are animals. VALID CHAIN ARGUMEN All snakes are animals RUE BECAUSE NONE OF HE INDIVIDUAL PROPOSIIONS ARE BLAANLY FALSE. FALSE SINCE HAVING PROECED SEX USUALLY HELPS US BE SAFE FROM DISEASE FALSE SINCE ONE CANNO BE A NEW YORKER AND A VIRGINIAN (I M SILL A VIRGINIAN, NO A NEW YORKER). RUE Formulate and write out a syllogistic argument that will satisfy the following conditions: 7) Valid but not sound. 8) rue but not sound. 9) Valid and true. 10) Invalid and false. AS YOU CAN SEE, YOU HAVE O FIGURE HIS ONE OU FOR YOURSELF. REMEMBER: A SOUND ARGUMEN MUS BE BOH VALID AND RUE. APPROPRIAE CRIICISMS OF AN ARGUMEN ARE: _NO 11) Your argument is false. _YES 12) Your conclusion is false. _YES 13) Your premises are false. _YES 14) Your argument is valid. _NO 15) Your conclusion is valid. _NO 16) Your premises are valid. _NO 17) You are arguing from false premises to a valid conclusion.

4 Matthews Key for Informal Logic Exercises 4 Matthews Philosophical Framework YES NO NO 18) Your argument is sound. 19) Your argument is not sound, but your conclusion is valid. 20) Your argument is sound, but not valid. Exercises for Step 3: Deliberate: EACH EXERCISE IS WORH 2 POINS FOR A OAL OF 25 POINS [13G is worth 1 point]: Write one example (of your own creation) of each of the following fallacies: (1) affirming the consequent (2) denying the antecedent, (3) equivocation (4) begging the question. (5) False dilemma (6) Straw Man AS YOU CAN SEE, YOU HAVE O FIGURE HIS ONE OU FOR YOURSELF. he following is a collection of all forms of fallacies, both fakes and distractions. It may include instances of false dilemma, straw man, affirming the consequent, denying the antecedent, equivocation, and begging the question. Identify the fallacy in each selection and discuss briefly why the fallacy makes the argument persuasive. 7A) FALSE DILEMMA: Obvious false dichotomy. If you can t lick em, then just leave them alone. 8B) BEGGING HE QUESION: here is no progression of reasons advanced in any of these propositions. Many people thought this was an instance of AC, but it is not. here are two main ideas at play here, and both are simply stated in circular fashion: 1 According to my theory, men who had doting mothers will seek women who are independent and not overly affectionate. his is a reaction to having been smothered by their mothers' affection. WHA S HAPPENING HERE? EQUIVOCAION BEWEEN DOING MOHERS AND MOHER S AFFECION HA MAKES I SEEM AS IF SOME NEW HOUGH IS BEING ADVANCED. 2 Now if my theory is correct, Ed would be attracted to someone like Carla. Ed is attracted to Carla. So I would say that my theory is correct. HAS HE AUHOR OFFERED ANY REASONS FOR CONCLUDING HA HIS HEORY IS CORREC? NO. HE MERELY SAES HA IS. A REASON FOR WHY I MIGH BE CORREC WOULD BE IF WE WERE OLD ABOU ED AND HIS MOHER S RELAIONSHIP O HIM. 9C) AFFIRMING HE CONSEQUEN:

5 Matthews Philosophical Framework If society is free, then creativity flourishes. 18 th century creativity flourished. ˆ 18 th century was free. 10D) FALSE DILEMMA: Simple. I hope. 11E) EQUIVOCAION: Job prospects or job are equivocated with vocation, thereby providing the illusion of a sequence or progression of thought in these sentences. 12F) FALSE DILEMMA: either you trust the people or you trust government. And our Republican Party ought to stand for trusting the people to spend their own money." 13G) BEGGING HE QUESION. [WORH ONLY ONE POIN!]