Constructing Valid Arguments: A Strategic Guide for Essays, Study Guides, Projects, Research of English Philology

Download Constructing Valid Arguments: A Strategic Guide for Essays and more Study Guides, Projects, Research English Philology in PDF only on Docsity! 1 Bob Muhlnickel Chris Tillman Argument in the College (DRAFT) The goal of CAS 105 is for you to learn to write successful argumentative essays. Argumentative essays, of course, consist of arguments. An argument, in this sense, is simply a set of statements, consisting of at least one argument-conclusion (hereafter, arg-conclusion) and at least one premise. The two main ways that an argument can go wrong are if its premises fail to support its arg-conclusion, or if its premises are not all true. While there is unfortunately no systematic procedure for ensuring that your premises are all true, this manual outlines a strategy for constructing cogent arguments that helps you avoid the first problem. The following explains in detail, by appeal to an extended example, how to Present, Explain, and Evaluate (PEE) an argument, step-by- step. An argument that is correctly PEE-ed is vastly clearer than a typical prose argument. In addition, the premises of a correctly PEE-ed argument are guaranteed to support its conclusion. Finally, by using PEE, you will have the advantage of being able to state exactly where an argument goes wrong. As a result, being able to correctly PEE arguments puts you at a significant advantage, particularly when the subject matter of the argument(s) is complex, as is often the case in college writing. The manual is organized as follows: there is a section on Presenting Arguments, followed by a section on Explaining Arguments, and a section on Evaluating Arguments. In each section, there is a brief outline of what is involved in Presenting, Explaining, and Evaluating, respectively. Following that is a more detailed explanation of each 2 component as well as some extended examples to serve as illustration. Finally, we discuss some critical reading and writing skills and how PEE can help you develop them. Presenting Arguments To present an argument, do the following: (a) Locate the conclusion of the argument and formulate it in clear, literal terms. (b) Locate the central premises from which the conclusion is derived, and formulate them in clear, literal terms. (c) Formulate implicit premises so as to make the argument valid. (d) Write out the entire argument in numbered premise-conclusion form. Locate the conclusion of the argument and formulate it in clear, literal terms. 1. What is the conclusion of an argument? The arg-conclusion of an argument is a statement of the position being argued for or against. It is the main claim for which reasons are provided. It is distinct from an essay conclusion, which is typically the essay’s closing section that summarizes the essay and/or makes clear the essay’s contribution to its topic, and reinforces the essay’s thesis. It is also worth noting the relationship between an arg-conclusion and a thesis or a hypothesis. The arg-conclusion is often not the thesis of the essay. If you are PEE-ing an argument that you came up with, the arg-conclusion of that argument will typically be a one-sentence statement of your paper’s thesis. But the arg-conclusion of an argument is often not the thesis. If you are PEE-ing an argument from a text, your thesis will often be the denial of the arg-conclusion of that author’s argument. For example, if you were to 5 identifies the explicit conclusion of an argument. For example, here’s an argument from the appendix of Morton White, What is and What Ought to be Done, p. 125: 1 (1) Whoever takes the life of a human being does something that ought not to be done. (2) The mother took the life of a fetus in her womb. (3) Every living fetus in the womb of a human being is a human being. (4) The mother took the life of a human being. (5) The mother did something that ought not to be done. In White’s argument, the arg-conclusion is clearly and explicitly stated in the last line of his argument. Arg-conclusion-finding tip 3:Look for the most comprehensive idea As you skim the work or a section, look for the most comprehensive idea. The most comprehensive idea is likely to be the arg-conclusion that the entire essay or the section supports. An argument is often constructed to support a comprehensive idea using premises to support the comprehensive idea. Here are some questions to have in mind when working on identifying the arg-conclusion: “What’s the main point of this work or section?” “What is this author arguing for?” “What idea does everything else lead to?” Arg-conclusion-finding tip 4: Read and re-read 1 A brief note about numbering may be in order. Rarely will you read a paper in which the argument is displayed using numbered sentences. However, it is useful to number the sentences in order to keep track of them when we are formulating our argument, even if the numbers do not appear in the final draft of your argumentative essay. 6 Often, the arg-conclusion is undetectable by a quick reading; you may need to re- read slowly and carefully. In addition, the passage may contain multiple arguments. Even a modestly complex work likely contains several arguments. The critical reader who identifies multiple arguments gains choices; she can write about the argument that is most interesting to her. It is worth noting that in many arguments, the arg-conclusion is not presented as straightforwardly as in Lepore’s or White’s arguments above. Consider the following argument from Judith Jarvis Thomson: Every person has a right to life. So the fetus has a right to life. No doubt the mother has a right to decide what shall happen in and to her body; everybody would grant that. But surely a person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body, and so outweighs it. What are some arg-conclusions one might draw from this argument? One might be that the fetus has a right to life. Another might be that the fetus’s right to life outweighs the mother’s right to decide what happens in and to her body. Note that this arg-conclusion is not explicitly stated in the above passage. Another arg-conclusion one might extract from the passage is that abortion is immoral. Note that this arg-conclusion is not stated at all. It is an implicit arg-conclusion. Many arguments contain implicit arg-conclusions. Your ability to identify these is parasitic on your ability to extract the main idea, most comprehensive idea, or thesis of a passage or work. Once you have formulated or located the conclusion, formulate it as a single declarative sentence in clear, literal terms. Avoid idioms, slang, metaphor, ambiguity, etc. In a good argumentative essay, the concepts and claims under discussion are difficult 7 enough; it is counterproductive to cloud your argument with misleading, ambiguous, or otherwise confusing language. Locate the central premises from which the arg-conclusion is derived, and formulate them in clear, literal terms. 1. What is a premise? The premises from which the conclusion is derived are the reasons given in support of the conclusion; that is, the reasons for thinking that the arg-conclusion is true. If you are PEE-ing an argument you came up with, the premises should include the main reasons you would give in support of your arg-conclusion. They are what you might say to convince an interested and intelligent neutral party that the conclusion is correct. This should consist of some supporting points and some reasons to suppose that the conclusion must be correct, given those points. Similarly, if you are PEE-ing an argument from a text, the premises are the main reasons the author gives in support of the conclusion. They are often answers to the question, “Why think that’s true?” For example, suppose our arg-conclusion is that it is not the case that the fetus’s right to life always outweighs the pregnant woman’s right to decide what happens in her body. Why might one think that’s true? One might think that any case of rape grossly violates a woman’s rights, so having an abortion in cases of rape is not outweighed by the fetus’s right to life. We could state our argument as follows: 1. Rape is a gross violation of a woman’s rights. 10 their field and, as a result, often do not explicitly state all of their premises. Writers investigating a topic with which they are unfamiliar may have difficulty identifying implicit premises. An instructor or reference librarian can often help you find sources of background information that experienced writers assume their readers possess. Here are some questions to have in mind when working on identifying premises: o What might support this arg-conclusion? o Are there combined statements or concepts in the arg-conclusion that are defended or explained individually in other parts of the work? o Does the author explicitly identify ‘evidence,’ ‘reasons,’ ‘support,’ or ‘warrants,’ in the text? (These terms also often indicate premises.) Finally, it is important to note that the premises may come before or after the conclusion. In the argument against abortion presented by Thomson, note that the premises precede the conclusion: Every person has a right to life. So the fetus has a right to life. No doubt the mother has a right to decide what shall happen in and to her body; everybody would grant that. But surely a person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body, and so outweighs it. By listing the premises and the arg-conclusion, we can Present a formal argument for the argument’s conclusion. Suppose we wish to extract an argument from Thomson for the arg-conclusion that abortion is immoral. The first premise from Thomson’s text could be (1) Everyone has a right to life. 11 The second premise could be: (2) So the fetus has a right to life. Recall that ‘so’ indicates an arg-conclusion. And (2) is one of the arg-conclusions we identified above. That’s OK; often, the arg-conclusion of one argument is a premise in another. In the argument we’re considering, (2) is part of the support for our main arg- conclusion, but it is in turn supported by (1). So in the argument we are constructing, (2) is a sub-conclusion. The third premise might be: (3) A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. A further sub-conclusion is: (4) So, a person’s right to life outweighs the mother’s right to decide what happens in and to her body. Finally, we might conclude: (5) Therefore, abortion is immoral. 12 Once you’ve completed this, you will have completed the first PEE step: Presenting an argument. We are now in a position to present Thomson’s argument as follows: 1. Everyone has a right to life. 2. So the fetus has a right to life. 3. A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. 4. So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 5. Therefore, abortion is immoral. It is worth noting that there is no unique, correct extracted argument for many passages that contain arguments. One of us extracted the following argument from Thomson’s passage: 1. Every person has a right to life. 2. If a person has a right to life, then s/he should not be killed. 3. A fetus is a person. 4. Therefore, a fetus should not be killed. This does not mean that all extracted arguments are equally good, however. Some may be better since they employ more plausible premises, some may seem more “logical” than others, or some may be more faithful to what the author had in mind. (1-5) includes an arg-conclusion and Thomson’s explicit premises. In the next section, we will discuss a strategy for adding implicit premises to an argument. Formulate implicit premises so as to make the argument valid. There are two ways an argument can go wrong: its premises can fail to support its arg-conclusion, or the argument could have false premises. If an argument’s premises fail to support its arg-conclusion, then the argument is invalid. If an argument has false 15 4*. Tweety is a bird. 4.5*. If Tweety is a bird, then it is probable that Tweety flies. 5*. Therefore, it is probable that Tweety flies. 6*. The last 10,000 swans I’ve seen have been white. 6.5*. If the last 10,000 swans I’ve seen have been white, then it is probable that, if I see another swan, it will be white. 7*. Therefore, it is probable that, if I see another swan, it will be white. In the remainder of this section, we’ll discuss a procedure for rendering any argument valid. End of digression We want our premises to support our conclusions. We’ve seen that an argument does not absolutely have to be valid in order to support its conclusion. So why is it so important that our arguments are valid? It is important for an argument to be valid because a valid argument is guaranteed to support its conclusion. With invalid arguments, there is no such guarantee. Valid arguments are like insurance for your essay. In addition, as we mentioned above, PEE-ing arguments and making them valid gives authors more choices since it often reveals weaknesses in an argument that are otherwise very difficult to detect. That is because rendering an argument valid reveals its implicit premises. So to quickly recap, in order to begin to PEE an argument, one must find the the arg-conclusion and the main premises used to support it. One should look for the arg- conclusion first and work backward to uncover the premises, using the strategies suggested above. Premises come in two flavors: explicit and implicit. Use the tips from the previous section to uncover explicit premises. Then follow the procedure in this 16 section to render the argument valid. In so doing, you will uncover the implicit premises in the argument, if any. The result is a correctly presented valid argument. So recall that an argument is valid if the truth of the premises guarantees the truth of the conclusion. But how do we know when the truth of the premises guarantees the truth of the conclusion? Some arguments are valid merely in virtue of their form. The form of an argument is the way in which its meaningful parts are “put together.” Consider the following argument: 23. Some swans are white. 24. Some pigs are fat. 25. Therefore, some swans are white and some pigs are fat. It is impossible for it to be the case that (23) and (24) are true, yet (25) is false, so (23-25) is valid. We can abstract away from the specific sentences used in (23-25) to make explicit the valid argument form. Consider (26-28): 26. Blahblah. 27. Bleeblee. 28. Therefore, Blahblah AND Bleeblee. If we replace ‘blahblah’ and ‘bleeblee’ with any sentences whatsoever, we form a valid argument. In (26-28), ‘blahblah’ and ‘bleeblee’ are place-holders for sentences. We sound less silly if we use capital letters instead of nonsense expressions. But which expressions should we abbreviate with capital letters? In order to find out, we need to distinguish between simple and compound statements. 17 A statement S is simple if, and only if, it does not contain any logical connectives. A statement S is compound if, and only if, it is not simple. Logical connectives are expressions that are used to build logically complex statements out of simpler statements. For example, the occurrence of ‘and’ in (25) functions to conjoin the simpler statements (23) and (24). The main logical connectives we will be concerned with are: Conjunction: ‘and’, ‘but’, ‘while’, ‘even though’, ‘yet’, ‘nevertheless’, ‘;’ 2 Negation: ‘not’, ‘it is not the case that’, ‘it’s false that’, ‘un-’, ‘im-’, some uses of ‘no’ Disjunction: ‘either …, or’, ‘or’ Conditional: If … , then … In order to correctly represent the logical form of an argument, we adopt the following rule: 2 ‘And’ may be used between statements to form a logical conjunction, as in: Bob was breakdancing and Chris was breakdancing. ‘And’ may also be used to conjoin sub-sentential expressions, like main verbs, auxiliary verbs, adverbs, objects, or subjects, as in: Bob killed and ate the innocent furry bunny. Bob was and will be breakdancing. Chris breakdances quickly and quietly. Bob ate hash and Twinkies. Bob and Chris fought the bad guys. Similar points hold for ‘or’, though ‘or’ may, in addition, be used to disjoin adjectives, as in: I have either the meanest or the ugliest instructor. 20 (1HS) If !, then ". (1R) Assume !. (2HS) If ", then #. . . . (3HS) Therefore, if !, then #. (nR) " and Not-". (Alternatively: if ", then Not-", and if Not-", then ".) (n+1R) Therefore, Not-!. Disjunctive Syllogism (DS) Dilemma (D) (1DS) ! or ". (1D) ! or ". (2DS) It’s not the case that !. (2D) If !, then #. (3DS) Therefore, ". (3D) It’s not the case that #. (4D) Therefore, ". And, as we saw above, Conjunction (C) (1C) ! (2C) " (3C) Therefore, ! and ". Any argument that has one of these forms is valid. That is, the truth of the premises guarantees the truth of the conclusion. Digression: Use of Greek Letters We use Greek letters to specify the argument forms instead of capital letters, since we chose capital letters to abbreviate only simple statements. The Greek letters may be replaced by either simple or compound statements. For example, the following argument is an instance of Modus Ponens: 21 35. If either Bob or Chris sings, then I’ll throw up and run away. 36. Either Bob or Chris sang. 37. So, I threw up and ran away. In (35-37), ! is ‘either Bob or Chris sings’ (and its paraphrases, ignoring tense) and " is ‘I’ll throw up and run away’ (and its paraphrases, again, ignoring tense). But since these statements are both logically compound, we cannot symbolize (35-37) as: 35*. If P, then Q. 36*. P 37*. Therefore, Q. Rather, we must symbolize (35-37) as: 35**. If (P or Q), then (R and S). 36**. P or Q. 37**. So, R and S. (Note that our choice of letters is arbitrary but our symbolization is not. Any letter may be used for any simple statement, as long as the resulting symbolization conforms to Rules 1 and 2.) End of Digression Another Digression: Validity-Checking Algorithms on the Web Logicians have devised powerful algorithms for detecting the validity of arguments. We will not study these procedures in this course. However, if an argument 22 is correctly symbolized, it may be checked for validity via these more powerful algorithms at the following websites: Truth Table Constructor: http://sciris.shu.edu/~borowski/Truth/ Truth Tree Proof Generator: http://www.umsu.de/logik/trees/ It is strongly recommended that you try to formulate your own arguments and the arguments you encounter in terms of the common valid argument forms, at least initially. End of Digression Let’s (finally!) see how to make an argument valid by adding implicit premises. In the remainder of this section, we consider three extended examples. In presenting each of the arguments, different issues arise that you might encounter when trying to render and argument valid. It is recommended that you read the first example carefully and skim the second two. Use these examples as guides if you are stuck when trying to validly formulate arguments on your own. Example I: A Simple Argument Against Abortion Consider the following argument: 1. If a fetus is alive, then intentionally killing it is murder. 2. So, abortion is murder. (1-2) seems logical. But is it valid? We can determine whether it is by symbolizing it to examine its logical form. We start by applying our Rule 1: Each simple sentence in the 25 (2DS) It’s not the case that !. (2D) If !, then #. (3DS) Therefore, ". (3D) It’s not the case that #. (4D) Therefore, ". Conjunction (C) (1C) ! (2C) " (3C) Therefore, ! and ". We may begin by noting the logical form of the arg-conclusion. Since certain forms always have a specific logical form for the arg-conclusion, we can eliminate certain candidate forms off the bat. For instance, the arg-conclusion is not of the form, “Therefore, ! and ".” So we can rule out Conjunction. We can also rule out Reductio and Modus Tollens, since the arg-conclusion is not of the form, “Therefore, Not-!.” Finally, we may rule out (HS), since the arg-conclusion is not of the form, “Therefore, if ! then ".” So the remaining candidate argument forms are: Modus Ponens (MP) (1MP) If !, then ". (2MP) ! (3MP) Therefore, " Disjunctive Syllogism (DS) Dilemma (D) (1DS) ! or ". (1D) ! or ". (2DS) It’s not the case that !. (2D) If !, then #. (3DS) Therefore, ". (3D) It’s not the case that #. (4D) Therefore, ". 26 Next, we can use the premise, (1), to give us a place to start on narrowing down candidate argument forms. Since (1) is a conditional, we can start with (MP). Let’s consider (MP) first. The most straightforward way to make the argument valid by Modus Ponens involves adding (MP2) as a premise. But what should the premise say? We want to fill in the following argument: (MP1) If a fetus is alive, then intentionally killing it is murder. (MP2) ???? (MP3)So, abortion is murder. It seems we should replace (MP2) with the ‘if’-part of (1), but according to the form of the argument, (MP2) should be the conclusion, (2). So it seems that the most straightforward way of trying to render (1-2) valid by Modus Ponens is either: (MP1) If a fetus is alive, then intentionally killing it is murder. (MP2) A fetus is alive (MP3) So, abortion is murder. (MP1) If a fetus is alive, then intentionally killing it is murder. (MP2) Abortion is murder. (MP3) So, abortion is murder. But neither of these arguments are instances of Modus Ponens. (Neither is even valid.) Note, however, that the following argument is valid by Modus Ponens: (MP1) If a fetus is alive, then intentionally killing it is murder. (MP2) A fetus is alive (MP3) So, intentionally killing a fetus is murder. 27 But this argument does not contain our conclusion. More work must be done. Let’s treat the third premise as a sub-conclusion and see if we can argue validly from it to our conclusion. So our goal now is to fill in the gaps in the following argument scheme: 1. If a fetus is alive, then intentionally killing it is murder. 2. A fetus is alive. 3. So, intentionally killing a fetus is murder. ???? Conclusion: So, abortion is murder. In symbols: 1. If A, then B 2. A 3. So, B ???? Conclusion: So, C So what we now want is a way of validly inferring C from B and some other premise or premises. But notice that by applying our procedure of comparing the logical form of the premise and the conclusion with our argument forms, we may infer the conclusion from (3) and the premise, “If B, then C” by Modus Ponens: 1. If A, then B 2. A 3. So, B 4. If B, then C 5. So, C We can justify each inference in this argument by Modus Ponens. Our sub-conclusion, (3), follows from (1) and (2) by Modus Ponens. Our arg-conclusion, (5), follows from (3) and (4) by another application of Modus Ponens. So (1-5) is valid; truth of its premises guarantees truth of its arg-conclusion. 30 3. A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. 4. So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 5. Therefore, abortion is immoral. Next, we check and see if the sentence we symbolized using ‘P’ appears anywhere else in the argument. It does not, so we may move on to (2). Is (2) a simple statement? As with (1), (2) is simple. But (2) is not a paraphrase of (1), so according to Rule 2, we need to assign it a different letter: (2) Q Since (2) is a sub-conclusion, we will retain the conclusion-indicator term in our symbolization: (2) So, Q Now we re-write our argument as follows: 1. P 2. So, Q 3. A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. 4. So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 5. Therefore, abortion is immoral. Let’s move on to (3). (3) is actually quite complicated, since (3) contains two occurrences of ‘and’. (3) may be understood as a conjunction of the following simple statements: (3a) A person’s right to life is stronger than the mother’s right to decide what happens in her body. (3b) A person’s right to life is stronger than the mother’s right to decide what happens to her body. 31 (3c) A person’s right to life is more stringent than the mother’s right to decide what happens in her body. (3b) A person’s right to life is more stringent than the mother’s right to decide what happens to her body. So let’s re-write (3) to make the conjunction more explicit: (3) A person’s right to life is stronger than the mother’s right to decide what happens in her body and a person’s right to life is stronger than the mother’s right to decide what happens to her body and a person’s right to life is more stringent than the mother’s right to decide what happens in her body and a person’s right to life is more stringent than the mother’s right to decide what happens to her body. Though writing (3) this way is much more stilted, it makes the logical form of (3) explicit. Now we need to assign letters to the simple sentences in (3). Since none is a paraphrase of any other or of ones that have preceded (though (3) and (4) have several phrases in common), we need to assign new letters to each of the simple statements in (3): 1. P 2. So, Q 3. R and S and T and U 4. So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 5. Therefore, abortion is immoral. 32 Now consider (4). (4) contains one occurrence of ‘and’. So we first re-write (4) to make its logical form more explicit: (4) So a person’s right to life outweighs the mother’s right to decide what happens in her body and a person’s right to life outweighs the mother’s right to decide what happens to her body. The simple statements in (4) are then assigned new letters: 1. P 2. So, Q 3. R and S and T and U 4. So V and W 5. Therefore, abortion is immoral. Finally, consider (5). (5) is a negation, as is signaled by ‘im-’. So we can understand (5) as saying, ‘It’s not the case that abortion is moral.’ We may now re-write our fully symbolized argument as follows: 1. P 2. So, Q 3. R and S and T and U 4. So V and W 5. Therefore, Not-X Now we check to see if the argument is valid. (1-5) is a compound argument, since it contains sub-arguments. So to check for validity, we need to check each sub-argument. The first sub-argument is from (1) to (2). If the form of the argument is either (MP), (MT), (DS), (D) or (C), then it’s valid. Unfortunately, our argument fits none of these forms! So even though the argument sounds pretty good in English, it turns out that its correct symbolization is invalid. That is, the truth of the premises does not guarantee the truth of the conclusion. What do we do? 35 4. R and S and T and U 5. If (R and S and T and U), then (V and W) 6. So V and W (from 4, 5 by Modus Ponens) 7. Therefore, Not-X A simple strategy to get us validly from some premises to an arg-conclusion is to conjoin and conquer. That is, we may infer the conjunction of those premises by (C), and then add a conditional premise to obtain the arg-conclusion. So the first step is to add another sub-conclusion which infers the conjunction of (3) and (6): 1. P 2. If P, then Q 3. So, Q (from 1, 2 by Modus Ponens) 4. R and S and T and U 5. If (R and S and T and U), then (V and W) 6. So V and W (from 4, 5 by Modus Ponens) 7. Therefore, Q and V and W. (from 3, 6 by Conjunction) 8. Therefore, Not-X Now we need add only one more premise to the argument to allow us to validly infer our conclusion: 1. P 2. If P, then Q 3. So, Q (from 1, 2 by Modus Ponens) 4. R and S and T and U 5. If (R and S and T and U), then (V and W) 6. So V and W (from 4, 5 by Modus Ponens) 7. Therefore, Q and V and W. (from 3, 6 by Conjunction) 8. If (Q and V and W), then Not-X 9. Therefore, Not-X (from 7, 8 by Modus Ponens) We now have a formally valid argument. To complete the argument’s presentation, let’s translate it back into English: 36 1. Everyone has a right to life. 2. If everyone has a right to life, then a fetus has a right to life. 3. So, a fetus has a right to life. 4. A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. 5. If (A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body.), then (a person’s right to life outweighs the mother’s right to decide what happens in and to her body). 6. So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 7. Therefore, a fetus has a right to life and a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 8. If (a fetus has a right to life and a person’s right to life outweighs the mother’s right to decide what happens in and to her body), then abortion is immoral. 9. Therefore, abortion is immoral. We have now successfully presented the argument. What follows are some passages that you can use to help you become acquainted with presenting arguments: We can now move on to explaining the arguments. (Note: depending on your instructor, the argument that you present may not be presented in numbered premise- conclusion form in your finished essay. In fact, presenting arguments this way is fairly uncommon outside of philosophy and some math.) Explaining Arguments To explain an argument that you have extracted, do the following: (a) Define all the technical terms that appear in the argument. (b) Give reasons for each of the premises of the argument. In some cases, the author’s text provides reasons to believe the premise. In other cases, you must provide reasons which would lead a reasonable person to accept the premise, 37 preferably reasons that you think the author would accept and that are consistent with the other premises of the argument. Define all the technical terms that appear in the argument. If your premises contain an expression that you expect is unfamiliar to your readership, or you are using a specific expression in a non-standard way, then that expression is a technical term for your readership and your argument. The first step in explaining an argument involves defining all technical terms, so your audience knows just what you mean by the argument(s) under consideration. Another reason to define technical terms is to avoid equivocation (using the same type of expression in two different ways), as in the following: 1. Barry Bonds swung a bat with cork in it. 2. A bat is a small flying mammal. 3. So Barry Bonds swung a small flying mammal with cork in it. (1-3) is a silly and obvious example of equivocation, but other cases are less silly and obvious. Here’s a more common argument whose appeal arguably depends on equivocation: 1. McX is a good general. 2. If McX is a good general, then he would be a good president. 3. So McX would be a good president. Evaluative terms such as ‘good’ are highly susceptible to equivocation. More commonly, technical terms will be the terms members of a particular discipline learn to use as ‘terms of art.’ They are usually unfamiliar to readers who are not members of the discipline and used with different meanings by different writers. Recall one of the arguments we considered above. 1. Everyone has a right to life. 2. If everyone has a right to life, then a fetus has a right to life. 3. So the fetus has a right to life. 4. A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. 40 offer reasons for the premises that support it. If the premises are true, then the sub- conclusion must be true also, since the argument is valid. 3. So the fetus has a right to life. Now consider premise (4): 4.A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. Here are reasons to think that (4) is true. (e) Since the right to life is the basis of all other rights and without living a person cannot exercise other rights, it takes more to violate the right to life than to violate the right to decide what happens in your body. (f) A right is more stringent than another if the right requires stronger reasons to override its exercise by the rights-bearer. The right to life requires stronger reasons to override it than the right to determine what happens in one’s body. Now premise (5): (5) If (a person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body) then ( a person’s right to life outweighs the mother’s right to decide what happens in and to her body). Since (5) is another conditional, we proceed by assuming the “if”-part and giving reasons for the “then”-part: (g) Suppose that a person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. We want to give reasons for thinking that is that is true, then a person’s right to life outweighs the mother’s right to decide what happens in and to her body. So, suppose that a person’s right to life does not outweigh the mother’s right to decide what happens in and to her body. Then a person’s right to life is not stronger and more stringent than the mother’s right to decide. So (5) is true. 41 (6) and (7) are sub-conclusions: (6) So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. (7) Therefore, a fetus has a right to life and a person’s right to life outweighs the mother’s right to decide what happens in and to her body. Line (6) Follows from (4) and (5) by Modus Ponens and (7) follows from (3) and (6) by Conjunction.No additional explanation is needed since these are sub-conclusions. Finally, consider (8) ( 8) If (a fetus has a right to life and person’s right to life outweighs the mother’s right to decide what happens in and to her body), then abortion is immoral. Since (8) is a conditional premise, we assume the “if”-part and give reasons for the “then”-part. (h) Suppose a fetus has a right to life and person’s right to life outweighs the mother’s right to decide what happens in and to her body. If a mother aborts a fetus, she disregards the fetus’s right to life in favor of her right to decide what happens in and to her body. But when someone disregards a more stringent right in favor of a less stringent right, then do something immoral. If that’s so, then abortion is immoral. So (8) is true. Line (9) is the conclusion. It follows validly from (7) and (8) By Modus Ponens, so no additional explanation is needed. . Here are some things to note about the process of giving reasons. First, not all the reasons given for the premises are equally good reasons. An important part of your CAS class will be learning about what makes a good reason. Second, giving reasons sometimes involves giving sub-arguments in support of a premise. Third, the explanations don’t 42 need to prove the premises; the explanations must give reasons for a premise that would appeal to a neutral and interested third party. Evaluating Arguments To evaluate an argument you have extracted and explained, do the following: (a) Identify the weakest premise of the argument and criticize it. Be sure to specify which premise you are criticizing. (b) Evaluate your evaluation: is the objection you present sound? Why or why not? If the objection is unsound, state which premise is false and why. Point out the weakest premise of the argument and criticize it. A good way to criticize an argument is to present another argument with a conclusion that is the negation of the premise you are criticizing. Be sure to explain that argument and to specify which premise you are criticizing. Recall the argument we are evaluating: 1. Everyone has a right to life. 2. If everyone has a right to life, then a fetus has a right to life. 3. So the fetus has a right to life. 4. A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body. 5. If (A person’s right to life is stronger and more stringent than the mother’s right to decide what happens in and to her body), then (a person’s right to life outweighs the mother’s right to decide what happens in and to her body). 10. So a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 11. Therefore, a fetus has a right to life and a person’s right to life outweighs the mother’s right to decide what happens in and to her body. 12. If (a fetus has a right to life and person’s right to life outweighs the mother’s right to decide what happens in and to her body), then abortion is immoral. 13. Therefore, abortion is immoral. In the paragraph below we give an example which criticizes premise (4) by presenting an argument that has for its conclusion ‘The mother’s right to decide what happens in and to her body outweighs a person’s right to life.’ Technically the negation of (4) would be ‘It