Differentiating Between Valid and Invalid Forms of Propositional Arguments Pages 164 – 175 of the textbook focuses on assessing valid forms versus invalid forms of propositional forms. It provides a brief description of what would be considered a valid argument and invalid argument. A valid argument passes the proper form test, while an invalid argument fails it. Five of the nine most used propositional arguments discusses are valid arguments. These valid forms include: the denying a disjunct, affirming an exclusive disjuncts, affirming the antecedent, denying the consequent, and the tri-conditional. On the other hand, four of those nine propositional arguments are invalid forms, therefore are considered fallacies. These fallacies include:
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One form it can take is, “(1) S1 or S2 (or both). (2) S1. Therefore, (3) Not S2,” (pp 166). An example of an argument with this form is, “She can have sprinkles or chocolate syrup on her ice cream (or both). She got sprinkles on her ice cream. Therefore, she can’t have chocolate syrup on her ice cream. With an inclusive disjunction you cannot conclude “not S1 or S2,” because you could have both. Thirdly, affirming an exclusive disjunct is a valid argument, and it can take two forms. It can take the form of, “(1) S1 or S2 (but not both). (2) S1. Therefore, (3) Not S2,” (pp 166). An example of this form is, “The dog is a male or female. The dog is a male. Therefore, the dog is not a female.” Fourthly, the fallacy of false dichotomy is an invalid argument. The textbook states this happens when, “a premise of an argument with a disjunction is false because there are other alternatives besides the two presented in the premise,” (pp 168). For instance, the argument,
“He is either a lawyer or a doctor. He is not a lawyer. Therefore, he is a doctor,” is a false dichotomy, because there are many different professions not just being a lawyer or …show more content…
The form of this argument is, “(1) If S1, then S2. (2) Not S1. Therefore, (3) Not S2,” (pp 172). An example of this form is, “If you break a mirror, then you will have bad luck. You did not break a mirror. Therefore, you will not have bad luck.” Seventhly, denying the consequent is a valid argument form. It takes the form of, “(1) If S1, then S2. (2) Not S2. Therefore, (3) Not S1,” (pp 172). An example of this valid argument form is, “If you break a mirror, then you will have bad luck. You will not have bad luck. Therefore, you did not break a mirror.” Eighthly, affirming the consequent is an invalid argument form. This argument takes the form of, “(1) If S1, then S2. (2) S2. Therefore, (3) S1,” (pp 173). For instance, the argument, “If you win the lottery, then you are lucky. You are lucky. Therefore, you won the lottery.” Lastly, the tri-conditional is a valid argument form. This argument takes the form of, “(1) If S1, then S2. (2) If S2, then S3. Therefore, (3) If S1, then S3,” (pp 174). An example is, “If people eat healthy foods, then they will be in better health. If people are in better health, then they will live longer. Therefore, if people eat healthy foods, then they will live
One form it can take is, “(1) S1 or S2 (or both). (2) S1. Therefore, (3) Not S2,” (pp 166). An example of an argument with this form is, “She can have sprinkles or chocolate syrup on her ice cream (or both). She got sprinkles on her ice cream. Therefore, she can’t have chocolate syrup on her ice cream. With an inclusive disjunction you cannot conclude “not S1 or S2,” because you could have both. Thirdly, affirming an exclusive disjunct is a valid argument, and it can take two forms. It can take the form of, “(1) S1 or S2 (but not both). (2) S1. Therefore, (3) Not S2,” (pp 166). An example of this form is, “The dog is a male or female. The dog is a male. Therefore, the dog is not a female.” Fourthly, the fallacy of false dichotomy is an invalid argument. The textbook states this happens when, “a premise of an argument with a disjunction is false because there are other alternatives besides the two presented in the premise,” (pp 168). For instance, the argument,
“He is either a lawyer or a doctor. He is not a lawyer. Therefore, he is a doctor,” is a false dichotomy, because there are many different professions not just being a lawyer or …show more content…
The form of this argument is, “(1) If S1, then S2. (2) Not S1. Therefore, (3) Not S2,” (pp 172). An example of this form is, “If you break a mirror, then you will have bad luck. You did not break a mirror. Therefore, you will not have bad luck.” Seventhly, denying the consequent is a valid argument form. It takes the form of, “(1) If S1, then S2. (2) Not S2. Therefore, (3) Not S1,” (pp 172). An example of this valid argument form is, “If you break a mirror, then you will have bad luck. You will not have bad luck. Therefore, you did not break a mirror.” Eighthly, affirming the consequent is an invalid argument form. This argument takes the form of, “(1) If S1, then S2. (2) S2. Therefore, (3) S1,” (pp 173). For instance, the argument, “If you win the lottery, then you are lucky. You are lucky. Therefore, you won the lottery.” Lastly, the tri-conditional is a valid argument form. This argument takes the form of, “(1) If S1, then S2. (2) If S2, then S3. Therefore, (3) If S1, then S3,” (pp 174). An example is, “If people eat healthy foods, then they will be in better health. If people are in better health, then they will live longer. Therefore, if people eat healthy foods, then they will live