Justification and Refutations of Arguments | PHIL 1504, Study notes of Reasoning

Download Justification and Refutations of Arguments | PHIL 1504 and more Study notes Reasoning in PDF only on Docsity! Chapter 13 Uses of Arguments • Justifications • Refutations Counterexamples Reductio Ad Absurdum Attacking Straw Men Refutation by Parallel Reasoning • System and Simplicity • Explanations • Excuses Justification The purpose of an argument: changing people’s minds vs. giving them ________ __________ to change their minds. What would count as a good reason to change one’s mind? Consider the difference between impersonal normative justification (i.e. having objective good reasons) and personal justification. [Second paragraph on p. 406] Also, consider the value of playing Devil’s Advocate. Discussion Question [p. 407] – Is it always illegitimate to try to convince someone else to believe something on the basis of a premise that you yourself reject? Why or why not? Consider a variety of cases. Refutations A refutation is an argument that provides a reason for ___________________ some argument or assertion. Refuting an argument [does or does not?] ___________________ require one to prove the opposite conclusion. Refutations take four main forms: 1. Argue that at least one of the premises is ______________ or ________________. 2. Argue that the __________________ leads to absurd results. 3. Show that the conclusion __________ _______ _______________ from the premises. 4. Show that the argument Begs the Question (i.e. assumes what it is trying to prove.) Example: 1. Murder is wrong. 2. Capital punishment involves murder. 3. Therefore, Capital punishment is wrong. Discussion Question - Why is this an example of a question begging argument? Counterexamples When a _________________ claim is refuted by a ____________ __________, that case is a counterexample. Example: Claim: All snakes Lay eggs. Counterexample: Rattlesnakes bear their young alive. There are two ways to defend a universal claim (i.e. all snakes lay eggs) against a purported counterexample (i.e. rattlesnakes bear their young alive): [Remember, a universal claim says that all things of a certain kind have a certain feature.] (1) Deny that the purported counterexample really is a thing of that kind (i.e. deny that rattlesnakes are snakes). (2) Deny that the purported counterexample really lacks that feature (i.e. deny that rattlesnakes bear their young live). Discussion Questions – There cannot possibly be any counterexamples to the following claims. Explain. 1. There is life on the moon. 2. All Bachelors are unmarried adult males. 3. Murder is wrong. 4. Killing is usually wrong. Reductio Ad Absurdum This mode/method of refutation can be directed at both premises and ___________________ to show that the proposition in question implies/leads to something ridiculous, absurd, counterintuitive, or an outright contradiction. That is, a reductio argument tries to show that one claim, X, is false because it implies another claim, Y, which is absurd. Discussion Questions – Consider a conclusion refuted by a reductio. The conclusion in question is then (most likely/probably) false: T/F ? Does a successful reductio show what, exactly, is wrong with the argument for the conclusion in question? What will it show? Evaluating reductios – To evaluate a reductio ad absurdum, the following questions should be asked: 1. Is Y ____________ ________________ ? 2. Does X really ______________ Y? 3. Can X be ______________ in some minor way such that it no longer implies Y? Construct a reductio to refute each the following claims and/or evaluate the refutation according to the above criteria. Given the criteria, is the reductio shallow/weak or deep/strong? 1. Claim: Some sisters are nephews. Reductio: Evaluation: 2. Claim: Most children in Lake Wobegon are above average in intelligence. Reductio: Evaluation: 3. Claim: The Civil War was wrong. Reductio: The disapproval of the Civil War is tantamount to the approval of slavery. No one approves of slavery. Therefore, it is not the case that the Civil War was wrong. Evaluation: The explanatory power of the conclusion gives us reason to believe it because ________________ ______________________________ and ____________________________________________. Explanations help us to understand why something is true. Turn the previous inference to the best explanation (the conclusion of which explains why Tom habitually gets off the elevator on the 10th floor and proceeds to take the stairs to the 12th floor) into an explanatory argument in standard form: 1. Tom is: 2. People who are: 3. Therefore, Tom must get off on the 10th floor. This explanatory argument starts with the hypothesis that was the conclusion of the inference to the best explanation. The difference is that this argument explains why the conclusion is true (i.e. why Tom gets off the elevator early) whereas the inference to the best explanation justified our belief in its (the inference’s) conclusion (i.e. that Tom is ________________________________). Evaluating explanations: What constitutes the best? Well, we don’t have a definitive set of criteria, but we can list some important factors. 1. Explanatory The hypothesis needs to explain ________ of the _______________________. Also, an explanation should raise new questions that need answering. That is, the explanation should not require an explanation itself. That is, the explanation should be deep. 2. Powerful One theory is more powerful than another if it explains more. 3. Falsifiable Explanatory power is important, but an explanation should not explain any possible event. Explanations must be falsifiable. Sir Karl R. Popper was a strong advocate of science as falsification. The following excerpt was originally published in Conjectures and Refutations (1963): [E]very conceivable case could be interpreted in the light Adler's theory, or equally of Freud's. I may illustrate this by two very different examples of human behavior: that of a man who pushes a child into the water with the intention of drowning it; and that of a man who sacrifices his life in an attempt to save the child. Each of these two cases can be explained with equal ease in Freudian and Adlerian terms. According to Freud the first man suffered from repression (say, of some component of his Oedipus complex), while the second man had achieved sublimation. According to Adler the first man suffered from feelings of inferiority (producing perhaps the need to prove to himself that he dared to commit some crime), and so did the second man (whose need was to prove to himself that he dared to rescue the child). I could not think of any human behavior which could not be interpreted in terms of either theory. It was precisely this fact—that they always fitted, that they were always confirmed—which in the eyes of their admirers constituted the strongest argument in favor of these theories. It began to dawn on me that this apparent strength was in fact their weakness. 4. Modest An explanation should not claim anymore than __________________________ ________________________________________________________________. 5. Simple Simple, in this case, does not mean easy to understand. Occam’s razor, that (all other things being equal) the simplest theory is most likely to be true, is a statement about probability. Postulating a bunch of extra particles, forces, and/or laws is undesirable in scientific practice. 6. Conservative The explanation for one observation should not conflict with other well- established beliefs. An example of this might be: ________________________ ________________________________________________________________. Arguments from Analogy An argument from analogy is an inductive argument which: ______________________________ ______________________________________________________________________________. Standard Form: 1. Object A has properties W, X, Y and also property Z. 2. Object B also has properties W, X, Y. 3. Therefore, Object B (probably) also has property Z. Evaluating arguments from analogy: First and foremost, the premises should be true. That should be pretty obvious. More importantly, the cited similarities (i.e. W, X, Y) must be _________________ and ___________________. That is, an object’s having properties W, X, Y should be _________________ to the fact that it also has property Z. If many objects have properties W, X, Y and lack property Z, then the argument from analogy is: [strong / weak] _____________________. On the other hand, if only a very small percentage of objects have W, X, Y and lack property Z, then the argument from analogy is: [strong / weak] _____________________. If there are relevant disanalogies, then the argument is: [strong / weak / depends on the disanalogy] _____________________. Consider the relationship between arguments from analogy and inferences to the best explanation. Reasoning about Causes Many explanations depend on causal generalizations. Think of at least three examples: 1. Car will not run without gas. 2. 3. 4. Causal explanation and causal prediction – these inferences contain two essential elements: 1. 2. What, exactly, is a causal generalization? Let’s just say it is a general conditional: For all x, if x has F, then x has G. Necessary and Sufficient Conditions According to the conditional above (i.e. IF x has F THEN x has G), x’s having F (the antecedent) is a sufficient condition for x’s having G (the consequent); and x’s have G (the consequent) is a necessary condition for x’s having F. Consider the following examples and explain a) why the antecedent is a sufficient condition for the consequent and b) why the consequent is a necessary condition for the antecedent. 1. IF your car is running, THEN it has gas. 2. IF you passed the class, THEN you turned in all of your homework. 3. IF you turned in all of your homework, THEN you passed the class. Concomitant Variation Method of Concomitant Variation: __________________________________________________ _______________________________________________________________________________ ______________________________________________________________________________. Given a strong __________________ between phenomena of types A and B, there are four possible explanations: 1. 2. 3. 4. Statistical Generalization In statistical generalizations, we cite characteristics of a ___________________ of a population to support a claim about the character of the ____________________ ____ ____ ____________. Statistical features of a ___________________ are used to make statistical claims about the ____________________ ____ ____ ____________. Evaluating statistical generalizations: There are (at least) four questions we can ask in our evaluation of arguments involving statistical generalizations. 1. Are the premises ____________________? 2. Is the sample too _______________ / _________________ enough? 3. Is the sample ________________? 4. Are the results affected by other sources of ________________?